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Bioavailable Isotope Ratios
Expected values for oxygen, strontium, and lead
isotope ratios can be predicted based on the sources
and location of rainfall (oxygen) or from the known
geological units present in an area (strontium, lead).
However there are often problems of fit between
expected and observed. Geological isotope ratios of
strontium and lead are not always a reliable indicator
of locally available (bioavailable) values (Montgomery
2010, Price et al. 2002, Sillen et al. 1998).
Differential erosion and solubility of the minerals in
whole rock can contribute to significant differences
between the geology and the bioavailable value.
Diet also can have a substantial impact on the isotopic
value of tooth enamel. Other anthropogenic or
atmospheric factors such as dust or sea spray may
alter the expected value. Oxygen isotope ratios, in
addition to being subject to seasonal, annual, and
long-term changes, exhibit substantial variation that
is poorly understood. Oxygen isotopes fractionate
along the path from rainfall to tooth enamel and exhibit
values that range over several per mil in a local
population.
There are several issues that require further discussion
with regard to the isotopic proveniencing of
human remains. These include establishing isotopic
levels in the local area, diet, identifying non-local
individuals, diagenesis, and multiple isotope studies.
Much of the discussion herein will focus on
strontium isotopes since this system provides the
foundation for human proveniencing in this study.
Establishing Local Isotopic Levels
In order to determine if “non-local” isotopic
values are present in an area, it is essential to know
what the local values are. This simple and obvious
requirement is more easily stated than accomplished
and is unfortunately not fulfilled in a number of published
studies. Expected values for oxygen, strontium,
and lead isotope ratios can usually be predicted
based on the sources and location of rainfall or the
known geological units present, respectively. However,
these theoretical expectations are often not met
in reality for a variety of reasons.
The direct use of strontium isotope ratios from
bedrock geology, for example, is confounded by
several factors. Isotopic ratios in the local environment
are composed of a mixture of strontium derived
from both atmospheric sources and mineral
weathering (e.g., Miller et al. 1993, Montgomery
2010). Biologically available strontium isotope
ratios can differ substantially between bedrock and
other environmental values. As Sillen et al. (1998:
2466) noted, “The large difference in strontium
isotope composition between plant and available
Sr on the one hand, and whole soil Sr on the other,
suggest that potential applications of 87Sr/86Sr
Isotopic Baselines in the North Atlantic Region
T. Douglas Price1,*, Karin Margarita Frei2, and Elise Nauman3
Abstract - The isotopic proveniencing of human remains, using ratios of strontium, oxygen, and/or lead isotopes, has been
employed in archaeology for more than two decades. The basic principles are essentially the same for the different elements
and involve comparison of isotope ratios in human tooth enamel with local levels from the place of burial. Because isotopic
ratios vary geographically, values in human teeth (place of birth) that differ from those of the local ratio (place of death)
indicate movement and identify non-local individuals. However, there is often no easy answer to the question of where an
individual came from because very distant and different places can have the same or similar isotopic ratios. To interpret the
results, baseline values for isotopic ratios must be available from the place of discovery and also from potential places of
origin. Estimates of isotopic ratios can be made for possible places of origin, either locations or regions, and bioavailable
data can be collected to compare with human tooth enamel. Isotopic proveniencing cannot provide “proof” of a place of
origin, only the possibility. This paper focuses on geographic variation in strontium and oxygen isotopes, specifically in
terms of the bioavailable ratios present in the different parts of the North Atlantic study area. We provide a detailed overview
of bioavailable isotope ratios. The discussion then moves to specific isotopic systems. The summary of strontium bioavailability
is detailed from region to region, considering first the bedrock and surficial geology followed by an evaluation of
bioavailable isotope ratios. We have also measured oxygen isotopes in human tooth enamel across the North Atlantic for
comparison. Baseline oxygen isotope ratios are considered in a more general fashion in this paper because these vary at
lower resolution across western Europe and a broader view is useful for understanding their distribution. We conclude with
a synthesis of bioavailable isotope data for the North Atlantic.
Viking Settlers of the North Atlantic: An Isotopic Approach
Journal of the North Atlantic
1Laboratory for Archaeological Chemistry, University of Wisconsin-Madison, Madison, WI, USA. 2National Museum,
Copenhagen, Denmark. 3Universitetet i Oslo, IAKH, Postboks 1019 Blindern, 0315 Oslo, Norway. *Corresponding author
- tdprice@wisc.edu.
2015 Special Volume 7:103–136
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relationships should use biologically available
strontium as a starting point, rather than substrate
geology per se.”
Thus, it is necessary to measure the baseline
bioavailable levels of these isotopes in a study area
(Price et al. 2002). The local isotopic signal can be
measured in several ways: in human bone from the
individuals whose teeth are analyzed, from other human
bones at the site, from archaeological fauna at
the site, or from modern flora or fauna in the vicinity.
Several studies measuring bioavailable isotope
ratios have been published (Evans et al., 2009, Maurer
et al. 2012, Price et al. 2002). Various materials
have been sampled including modern vegetation,
soil, sediment leachates, and water. While there is
no perfect proxy for bioavailable isotope ratios, we
have for the most part used archaeological fauna in
this study.
Because bone is subject to contamination and
diagenesis and the affect of diagenesis on the isotopic
signal is uncertain, we generally do not use
human bone from burials. We prefer to measure
archaeological fauna, when available, to establish
the bioavailable levels of strontium isotopes in the
local environment (Price et al. 2002). Small wild
mammals are a good choice because they have small
home ranges, are unlikely to have been imported,
and incorporate local strontium into their bone or
teeth over months or a few years in most cases.
Diagenesis of the bones of archaeological fauna is
irrelevant for our purposes since the contaminant
material is composed of local strontium.
Samples are difficult to obtain, and measurements
are expensive. As a consequence, baseline
studies have rarely been done at an adequate level of
intensity (cf., Knipper 2011). However, knowledge
of baseline variation is the best way to distinguish
local and non-local individuals. Determination of
the local range of bioavailable isotope sources provides
a means to determine where to draw the line to
separate local from non-local individuals and is thus
a very important step in isotopic proveniencing of
human remains.
Non-geological sources of strontium
There are several atmospheric sources than can
alter the normal geological 87Sr/86Sr values in an
area: sea spray, rainwater, and atmospheric dust. In
addition, the use of fertilizers on agricultural lands
has the potential to change strontium isotope ratios,
and their potential impact will be considered. It is
also critical to remember diet and the sources of
food consumed in the past when evaluating the local
bioavailable isotope ratios. Thus, we discuss as well
in this section the role of diet in determining isotope
ratios.
Sea spray and rainwater. Sea salt, produced
by the oceans, makes a large contribution to atmospheric
particles. There are numerous studies (e.g.,
Chadwick et al. 2001, Vitousek et al. 1999, Whipkey
et al. 2000) that have reported substantial fractions
of Sr in plants and soils in coastal areas from marine
sources (through rainfall or sea-spray). Gosz and
Moore (1989) analyzed precipitation from coastal
and inland regions in the western US and found
that precipitation nearer the ocean generally had a
87Sr/86Sr values similar to that of seawater. Seawater
contributed 90% of the Sr to snowfall near the coast
but only 10–30% some 300 km inland.
Average residence time in the atmosphere for sea
salt is 3 days (Berner and Berner 1987). Sea spray
contains substantial amounts of sodium as well
as calcium, strontium, and other elements (Junge
1972). The strontium isotope ratio of sea spray will
be the same as seawater, 0.7092, and we expect that
plants and animals taking in this strontium should
exhibit values somewhere intermediate between the
local terrestrial ratio and the sea. Measurement of
marine aerosols in southern Sweden showed transport
across the entire region, a distance of some
300 km, with a decrease in concentration downwind
(Franzén 1990). A study in the Outer Hebrides
(Montgomery and Evans 2006, Montgomery et al.
2003) found that although the island was underlain
by radiogenic granites and gneisses (87Sr/86Sr
of ~0.715), seawater dominates the bioavailable
isotope ratio, which is less than 0.7105. Frei et al.
(2009) report similar sea spray effects in sheep from
the Shetland and Faroe Islands. Given the proximity
to the sea of animal pastures, it is very likely that the
soluble portion of Sr in the soils (and consequently
the Sr in the respective wool samples) is dominated
by sea-spray and rainwater derived from evaporated
seawater.
We have observed this effect in our own studies
as well. A 87Sr/86Sr value of 0.703 has been reported
for geological samples from Iceland’s basalts (Moorbath
and Walker 1965, Sun and Jahn 1975, Wood et
al. 1979). Yet Price and Gestsdottir (2006) measured
higer ratios for modern fauna (0.705–0.706) and human
enamel (0.706– 0.715). The values in modern
fauna and Viking teeth are higher than the geological
values for Iceland likely primarily due to sea spray.
Other researchers have also documented the concentrations
and distribution of sea spray in Iceland
(Kettle and Turner 2007, Lovett 1978, Prospero et al.
1995). Arnórsson and Andrésdóttir (1995) reported
that the high levels of chlorine and boron in the
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natural waters of Iceland are mostly due to marine
aerosols and sea spray.
Rainwater in coastal areas is also a likely factor
in introducing non-local 87Sr/86Sr values. Åberg
(1995) reported a value of 0.706 from a farm reindeer
on Iceland, where grass growing on volcanic
soil had a 87Sr/86Sr ratio between 0.703 and 0.704.
He suggested that rainwater, with a 87Sr/86Sr ratio
of about 0.709, was responsible for the higher than
expected value. Evans and Bullman (2009) found
significant sea spray and rainwater effects in a study
of migratory shorebirds in Iceland and Scotland.
Raiber et al. (2009) demonstrated the clear effect of
rainwater with a non-local 87Sr/86Sr value, changing
groundwater ratios in southeastern Australia.
In sum, we would expect that sea spray and rainwater
in coastal areas will alter natural geological
strontium isotope ratios in many parts of the North
Atlantic and result in those values moving toward
0.7092. Nevertheless, there remain significant
87Sr/86Sr differences between geological regions that
have utility for human provenience studies.
Atmospheric dust. Atmospheric dust is another
potential source of strontium in local sediments and
the food chain. Varying effects have been reported
in the literature. Aeolian sediments such as loess
or volcanic ash are obvious and often substantial
additions to the local surface geology. Chadwick
et al. (2001) and Stewart et al. (2001) reported that
wind-transported silt traveled 6000 km from China
to Hawai’i and contributed substantially to the strontium
in the soil. In the Sangre de Cristo Mountains
of New Mexico, 50–75% of the strontium in local
vegetation is derived from atmospheric deposition
(Graustein and Armstrong 1983, Miller et al. 1993).
Effects of atmospheric dust in Scandinavia and the
North Atlantic are uncertain.
Lupker et al. (2010) have reported atmospheric
dust dating from 18th century in a Greenland ice core
ranging from 0.709 to 0.720 87Sr/86Sr, and suggested
that dust from both China and the Sahara had been
deposited in the Greenland ice. If such dust were
accumulating in sufficient amounts to change plant
nutrients in the ice-free parts of Greenland, then
we might expect to see some reduction in the local
bioavailable values. Measured values, however,
generally remain high, indicating that the amount of
atmospheric dust deposited is likely quiet low.
Fertilizer. In addition to sea spray and atmospheric
dust, several authors have argued that some
modern fertilizers also contain distinctively higher
strontium isotope ratios and might shift differences
between observed geological and bioavailable values.
Böhlke and Horan (2000), for example, reported
that soils with normal 87Sr/86Sr leachate values of
~0.708 are enriched by fertilizers with higher radiogenic
ratios (~0.715) to 0.713–0.715 in coast areas
of Maryland. Other studies, however, indicate that
the effect of fertilizers is not a major factor. Vitoria
et al. (2004) measured strontium isotope ratios in 27
different fertilizers from Spain and in all but a few
cases found 87Sr/86Sr values below 0.709. Sattouf et
al. (2007) measured in a series of phosphate fertilizers
and report a wide range of values (0.703–0.709).
Frei and Frei (2011) in a review of literature on the
analysis of Danish surface waters and strontium
concentrations in fertilizers concluded that fertilizer
strontium contamination of Danish surface waters
was minimal. In sum, the role of fertilizer in raising
natural biogenic levels of 87Sr/86Sr does not appear
significant in most areas of interest in this study .
Diet. A certain proportion of the variability in
isotope ratios used for human proveniencing is due
to differences in diet, rather than place of birth.
In fact, one of the early applications of strontium
isotope ratios in archaeology (Sealy et al. 1991)
focused on the use of 87Sr/86Sr as a dietary indicator
in modern and archaeological bone. The application
of 87Sr/86Sr in the study of modern populations, often
suggested in forensic contexts (Beard and Johnson
2000), is probably not viable, at least in much of the
developed world. Our foods today come long distances,
often from other continents. For this reason,
the isotope content of an individual’s foods today
can be highly varied and produce an unreliable signal
of place of origin.
In the past, however, most foods would have
been of local origin for the majority of the populations
archaeologists study. The range of variation
in isotopic ratios in tooth enamel for a particular
location, however, will depend on the variation in
the sources of isotopes among the places where food
is obtained. In a homogeneous isotope environment,
there should be relatively little variation in enamel
isotope ratios among individuals. In a heterogeneous
isotope environment, however, variation in enamel
isotope ratios will be greater and will depend on the
proportion of different isotope sources incorporated
in the diet of the individual.
It is useful at this point to return to the Iceland
data for a simple example using strontium isotopes.
It is essential to remember that there are 2 major
sources of strontium in the human diet on Iceland:
1. Terrestrial (basalt 0.703 + sea spray 0.709 equals
a baseline of 0.704–0.707), and 2. Marine (0.7092).
Thus, the highest 87Sr/86Sr value available to the
human population on Iceland is 0.7092, and any
samples with values above that level must be nonJournal
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T.D. Price, K.M. Frei, and E. Nauman
2015 Special Volume 7
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local. Human diet on Iceland during the Viking period
was a mix of terrestrial and marine foods (e.g.,
Sveinbjörnsdóttir et al. 2010). Therefore, values in
humans who lived in Iceland should range between
0.703 and 0.7092. Fifty-one of 83 individuals we
tested had a measured ratio between 0.706 and
0.7092, indicating they spent their lives in Iceland.
Thirty-two individuals we tested had ratios above
0.7092, and thus were apparently non-local, not born
on Iceland.
This example highlights the importance of knowing
local bioavailable values and having some information
on the composition of human diets in the
past. In other parts of the world, there may be several
different geological formations in close proximity to
potential places of origin. In such cases, sampling of
bioavailable sources should include these different
terrains to insure that such differences are considered
in the analysis. This information allows us to
interpret the variation present in enamel ratios and to
distinguish between local and non-local individuals
in the sample set.
Identifying Non-Local Individuals
Some years ago, Price et al. (2002) suggested
that the mean and standard deviation of strontium
isotope ratios in a population be used to determine
outliers to identify the non-local individuals in a
set of samples. At the time, much of isotopic proveniencing
was still experimental and there was
no established procedure for distinguishing locals
and non-locals. Since then, we have analyzed several
thousand samples and often measured a large
number of samples from single sites. Based on our
experience with larger samples, we now would argue
against using mean and standard deviation statistics
in favor of common sense and the range of bioavailable
values in an area (Price et al. 2010).
The research in the North Atlantic was one of the
primary reasons we have abandoned the statistical
assignment of non-local individuals. Specifically, a
series of samples from Iceland provide an important
lesson regarding isotopic variability in human populations.
Iceland is an exceptional place in many ways.
It is one of the youngest landmasses on earth, spewed
from the Mid-Atlantic Ridge as a large volcanic
island over the last 20-25 million years. For this reason,
the strontium isotope ratios on Iceland are very
low and quite distinct from many other areas around
the rim of the North Atlantic (Moorbath and Walker
1965, Sun and Jahn 1975, Wood et al. 2004).
In order to determine the baseline bioavailable
87Sr/86Sr values on the island, we measured enamel
from domestic animals, including modern sheep
and archaeological cattle from different parts of
Iceland. We were surprised to note that bioavailable
strontium isotope ratios were significantly different
from the basalt rock. Sheep tooth enamel from
four locations around Iceland averaged 0.706, while
two cows from northern Iceland provided values of
0.704. Sea-spray and rainfall are likely responsible
for the higher than expected bioavailable value
witnessed in modern fauna on Iceland. A number
of researchers have documented the concentrations
and distribution of sea spray in Iceland itself (e.g.,
Kettle and Turner 2007, Lovett 1978, Prospero et
al. 1995). As noted above, rainwater will have the
same 87Sr/86Sr value as the ocean from which it originates.
The 87Sr/86Sr of sea spray and rainwater will
be 0.7092, and plants and animals consuming this
strontium will exhibit values somewhere intermediate
between the basalt rock of Iceland and the sea.
This is the pattern we observe in the fauna, flora, and
humans on Iceland.
Bioavailable Isotope Ratios in the North Atlantic
In this context, we establish on a case-by-case
basis the range of bioavailable strontium isotope
values across the North Atlantic and discuss the
criteria for each. A country by country review of the
geology provides an indication of expected levels of
bioavailable 87Sr/86Sr, while analysis of both modern
and archaeological samples reveals some of the
actual bioavailable ratios present. These data come
from a variety of different materials and include
both our own measurements and data published elsewhere.
Oxygen isotope ratios in fresh water vary along
several dimensions including latitude, elevation,
distance from sources, amount of rainfall, and the
nature of the freshwater source (e.g., well, stream,
spring, reservoir). Oxygen isotope ratios also vary
seasonally and over time with climatic change. Because
of this variability and the absence of sufficient
baseline information, modern oxygen isotope values
are often used as background for archaeological
studies. Oxygen isotopes will be reviewed herein for
the North Atlantic region as a whole. Lead isotope
background will be considered in a later publication.
Strontium isotopes
The geology of Scandinavia, Britain, and the
other islands of the North Atlantic reflects a highly
variable array of strontium isotope ratios. Generally
speaking, some of the oldest rocks on the continent
are to be found in Greenland, Norway, parts of
Sweden, and the northern parts of Britain and Ireland.
Also in general terms, with the exception of
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Greenland, the oldest rocks and highest strontium
isotope values are to be found in the more northerly
parts of these areas.
An important consideration in the isotope
proveniencing of human remains is the geological
variability in the study area. In the case of the
North Atlantic, the geological context is almost
ideal for such a study. Some of the biggest differences
in reported strontium isotope ratios anywhere
come from this region. We will focus on Greenland
and Iceland and the potential homelands for these
colonists. The most probable places of contact and
origin for these settlers include the northern British
Isles, Ireland, and the west coast of Norway. These
areas in the North Atlantic generally have higher
strontium isotope ratios than Iceland. Other areas
of Norse homeland such as Denmark, Sweden, and
northern Germany are regarded as less likely to
have provided colonists to the uninhabited Atlantic
islands, but may potentially have been homelands
for some Viking settlers in the British Isles. We will
not overlook this possibility, and will consider these
areas as well in our isotopic analysis of more than
500 samples of Norse burials and archaeological
fauna from settlements. The majority of our samples
come from Scandinavia, Iceland, and Greenland.
We also incorporate published data from the British
Isles along with a few small studies we have been
involved with in that region. In our discussion of
strontium isotope variation below, we move from
east to west, from the Norwegian Coast to the British
Isles to Greenland.
We give more attention to those areas where
there is less information. There is a good bit of data
available for bioavailable strontium isotopes in
Denmark (Frei and Frei 2011, Frei and Price 2012)
and England (e.g., Evans et al. 2010, 2012). Mention
should perhaps be made here of a pan-European
study of the distribution of 87Sr/86Sr for the commercial
analysis of the origins of various foodstuffs
(Vorkelius et al. 2010). This last study, while frequently
cited, is based on limited sample points in
many areas and often fails to capture the diversity or
range of bioavailable 87Sr/86Sr values in a particular
area.
Denmark. Denmark is characterized by a relatively
young (geologically) and homogenous
“basement” geology. About 50% of the country
is constructed of Late Cretaceous–Early Tertiary
carbonate platforms, and the other 50% of marine
clastic sediments, all covered by more or less thick
sequences of diverse glaciogenic sediments deposited
during the two last Ice Ages. The Quaternary
glaciogenic sediments are composed, among other
things, of various weathered Precambrian granitoids
(gneiss and granite) from Norway and Sweden. Almost
everywhere in Denmark, the glacial deposits
are the source of strontium isotopes for plants, animals,
and people. There is very little bedrock exposure
anywhere in the country. Frei and Price (2012)
presented strontium isotope ratios from samples of
modern mice, snails, and archaeological fauna (Fig.
1). We compared these ratios with strontium isotope
median values from human enamel samples from
archaeological sites within Denmark. The fauna
samples range from 87Sr/86Sr = 0.70717 to 0.71185
with an average of 0.70918. The humans (including
non-locals) samples range from 87Sr/86Sr = 0.7086 to
0.7110, with an average of 0.7098.
Frei and Frei (2011) measured 87Sr/86Sr in almost
200 samples of Danish surface water and found
similar results. In both these data sets, we observed
a small difference between the baseline values in
the western (Jutland) and eastern (Funen, Zealand,
and the southern islands) parts of Denmark. Therefore,
we have proposed 2 slightly different baseline
ranges for the bioavailable strontium isotopic values
within Denmark. The western area has a 87Sr/86Sr
range = 0.7079–0.7099, whereas the eastern portion
of the country has a 87Sr/86Sr range = 0.7089–0.7108.
Because of the overlap in values, however, it is not
really possible to distinguish individuals from these
2 areas isotopically.
Sweden. With the exception of the southwest
corner of the country, Sweden’s geology is rather
complex but generally can be divided into 3 main
components: Precambrian crystalline rocks (which
are part of the Baltic or Fennoscandian Shield, and
include the oldest rocks found on the European continent),
the remains of a younger sedimentary rock
cover, and the Caledonides formation (Fredén 1994).
The bedrock is covered in places by glacial moraine,
but often is exposed intermittently to frequently on
the surface, especially in the northern half of the
country.
The oldest rocks in Sweden are Archean (>2500
million years old), but they only occur to a limited
extent in the northernmost part of Sweden. Most of
the northern and central parts of Sweden consist of
Precambrian rocks belonging to the Fennoscadian
Shield, an ancient craton of mantle rock with generally
high strontium isotope ratios. The Swedish
Geological Service (SGU) has measured 87Sr/86Sr
across the country and reports very high rock values
from much of this region, generally greater than
0.722 (Sjogren et al. 2009). Further to the south,
Phanerozoic sedimentary rocks rest upon the Precambrian
shield area. They are less than 545 million
years old and cover large parts of Skåne, the islands
of Öland and Gotland, the Östgöta and Närke plains,
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numbers per site are too small to provide much more
information. Specifically, values generally range
from 0.711 to 0.714 and probably reflect the local
range in Bohuslän. A few higher values in the sample
may well reflect non-local individuals buried in this
region.
We also have some additional data from the
southern and eastern parts of Sweden as well, and,
as discussed below, there are published data from
northern Sweden and the Gulf of Bothnia region.
These areas probably lie outside the homelands of
the Viking settlers of the North Atlantic. Most of the
Vikings in the Baltic region appear to have looked
to the east in terms of expansion as large settlements
appeared in the eastern Baltic and Russia (Boba
1967, Noonan 1991, Sawyer et al. 1982), where they
have been viewed either as either founders of the
state or peripheral pirates (Noonan 1991).
A major set of 87Sr/86Sr data from the west coast
includes 160 samples, 78 from fauna and 82 human
(Sjögren et al. 2009). From the east coast and Gotland,
we have ~40 samples, of which 8 are faunal
(T.D. Price, unpubl. data). These data are summathe
Västgöta mountains, the area around Lake Siljan
in Dalarna, and areas along the Caledonian front in
northern Sweden. The youngest rocks in Sweden are
Tertiary rocks, formed about 55 million years ago.
They occur in the most southerly and southwestern
parts of Skåne. Quaternary deposits formed during
and after the latest glaciation (when Sweden was
completely covered by the inland ice sheet) partially
covered the bedrock. The most common soil type in
Sweden is till, covering about 75% of the landscape
(SGU Soil Map of Sweden). Southernmost Sweden
is a glaciated landscape much like the neighboring
areas of Denmark, and expected strontium isotope
ratios in this area should be similar as well.
The west coast of Sweden was an area of known
Viking settlement and a potential homeland for settlers
of Iceland and Greenland. Studies along the
west coast of Sweden provide some information on
levels of 87Sr/86Sr in this region (Fig. 2). As part of a
study of inland Neolithic sites in this area, Sjögren et
al. (2009) measured a few samples of human enamel
from sites in the coastal region. These samples
exhibit substantial variation, although the sample
Figure 1. Strontium isotope samples from fauna and human tooth enamel from Denmark and adjacent areas (Frei et al.
2012).
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0.7174 ± 0.0078. A bar graph of the ranked 87Sr/86Sr
values provides a look at the data (Fig. 3). The last
two values stand out as significantly higher than the
others and very likely identify non-local individuals.
In sum, it is clear that the older rocks of the Fennoscandian
Shield dominate most of Sweden and
have high 87Sr/86Sr, above 0.711 with some higher
than 0.735. These rocks are surficial and contribute
to soil nutrients and hence to bioavailable strontium
isotopes. Lower values around 0710–0.711 were
found only in the southernmost part of the country
in the province of Scania, on the island of Gotland
in the Baltic, and in a few limited areas along the
coasts.
Norway. The Fennoscandian Shield covers Norway,
most of Sweden, large parts of Finland, and the
northwestern part of Russia. In Norway, there are
some outcrops of Archaean rocks (very old—up to
3.5 billion years of age) exposed between younger
metamorphic belts (Fig. 4). A special feature that
characterizes Norway’s geology is the intense
metamorphism/reworking that
heavily altered the rocks there
during the Caledonian orogeny,
Today the region is composed
primarily of crystallines and
metamorphites. There are 3 major
geological provinces in Norway.
In the Oslo area and to the
south down into Sweden lies the
Southwestern Gneiss Province of
1700- to 900-Ma-old rocks. This
southwestern gneiss province is
divided in 2 parts by the Caledonides
Province, formed during
an ancient mountain-building episode
in the Mesozoic, ca. 400 Ma
ago. In the south and southwest
where the Norwegian peninsula is
wider, the southwestern gneiss is
rather broad, but to the north only
the coastal islands are composed
of this gneiss.
The Caledonides form the
backbone of the entire country,
stretching from southern Norway
to the Arctic Circle, characterized
by a rugged topography and
peaks up to 2500 m in elevation.
The Caledonides are made up of
metasedimentary and metavolcanic
rocks dating from 700–400
Ma ago. The Oslo Rift province
runs through the Oslo region and
the fjord, composed of younger
rized in Figure 2. Two additional sites on this map
come from Frei et al. (2009) and were measured on
sheep wool from Dannås and Boserup. The Dannås
sheep (0.716) was grazing on pastures with soils developed
on very old Precambrian basement gneisses
typical of Swedish bedrock, while the Boserup sheep
(0.711) fed on soils developed in sedimentary rocks
from a Late Triassic–Early Jurassic flooding event.
We have 10 or more samples from several sites in
eastern Sweden and the pattern of 87Sr/86Sr is similar
at each (T.D. Price, unpubl. data). There is a high
proportion of what appear to be local values showing
a continuous range and then a few significantly
higher values that very likely represent individuals
from inland areas or much older terrains. The site of
Birka near modern Stockholm was an important Viking
center and the gateway to the east [(T.D. Price,
unpubl. data). Much of the trade from Russia and the
Arab world passed through Birka. We have sampled
10 individuals from the cemetery at Birka. These
values range from 0.7103 to 0.7335, with a mean of
Figure 2. Averaged strontium isotope ratios from human and archaeological fauna
(blue) from southern and central Sweden.
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magmatic rocks of Permian age, 300–250 Ma ago.
Neumann et al. (1988) have measured strontium
isotope ratios in these old basaltic to granitic rocks.
The volcanics, as expected, exhibit 87Sr/86Sr values
in the range of 0.704–0.706, whereas the granitic
rocks have very high values, ranging from 0.715 to
0.760 along with several higher values of 0.80, 0.90,
and even 1.0. The valley floors and lower-lying areas
of this largely mountainous region are buried under
moraine and other deposits of glacial origin, often
with lower strontium isotope values. The old age of
some of these rocks suggests that 87Sr/86Sr values in
Norway should be high. Values measured on granites
and gneiss in southern Norway range from 0.7087
to 0.7185 and even 0.7519 and higher (Wilson et al.
1977).
While bare rock with only thin ground cover is
present in much of Norway, there are Quaternary
deposits in local areas that provide sediments for
soil development and some cultivation. Ground
moraine and meltwater deposits are more common
in the northeast and southeast of the country. Marine
deposits occur in the region of the Oslo fjord and
around the coastal zones of Bergen and Trondheim.
Peat bogs are scattered across the landscape in lowlying
areas.
There are 2 published reports of strontium isotope
ratios in biological materials from Norway. Frei
et al. (2009) report a very low value of 0.7051 from
sheep wool from Hemsedal in central Norway. The
sheep is reported to have pastured on fields overlying
predominantly Proterozoic mafic metamorphic
rocks, which may explain such low values. Åberg
et al. (1998) reported values ranging from 0.7077
to 0.7323 for 4 samples of Medieval human tooth
enamel from different localities in southern Norway.
We have measured a variety of archaeological
and modern fauna and human remains from Norway
to learn more about the bioavailable levels of strontium.
Figure 5 is an outline map of Norway with a
summary of our results. Values from sites with more
than 1 sample are averaged unless they were highly
divergent. Coverage is generally good along the
west coast of Norway, but inadequate on the south
coast. A number of samples are also available from
the Oslo region and from some of the settled valleys
in the interior.
We measured 211 samples for strontium isotopes
from Norway. This total includes 155 humans and
56 floral and faunal samples. The human data are
discussed in Price and Nauman (in press, [this volume]).
The floral and faunal remains include 1 horse,
1 cow, 5 plants, 2 snails, 15 beaver, 16 pigs, and
16 unknown species. The range of values for these
samples is 0.7073–0.7254, with a mean of 0.7131 ±
0.0043.
Several patterns emerge from the distribution of
values. It is clear that a number of the lower values
in Norway are found in the coastal areas where marine
diets may have been prevalent and sea-spray
effects were likely most
pronounced. These lower
values are particularly noticeable
in the Oslo fjord
area where the glacial moraine
and marine sediments
appear to contribute to values
around 0.709–0.710.
Bedrock 87Sr/86Sr in this
area is also lower because
of the old igneous province
here.
Inland areas in general
show much higher average
values. At the same
time, on the west coast of
Norway, at least, virtually
all of the population lived
along the sea. The general
pattern of lower values
in coastal areas is strong.
However, there are also
some higher values along
the coast, and in several
Figure 3. Bar graph of ranked 87Sr/86Sr values from human tooth enamel from Birka,
Sweden.
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substantial amount of food from the sea. The beaver
87Sr/86Sr data are generally higher than other fauna,
with 2 exceptions (probably from areas of marine
deposits) found in eastern Norway. We can assume
that the beaver reflect the local bioavailable 87Sr/86Sr
for a specific location.
Another sample of archaeological fauna comes
from pig bones from medieval Bryggen (Bergen).
These pigs were analyzed to obtain more bioavailable
information for the Bryggen area. The mean and
cases in close proximity to lower values. The question
regarding the human data is whether the variation
reflects local values, movement, or diet.
The beavers should provide a good indication of
local bioavailable values without the influence of
long-distance movement or marine diets since beavers
tend not to range far and primarily eat trees. The
human remains can be non-representative if they
are non-local individuals, i.e., moved to the place
of burial from elsewhere, or if their diet included a
Figure 4. Geological map of Norwegian bedrock (Geological Survey of Norway, NGU).
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2015 Special Volume 7
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pigs ate fish or other marine foods, their terrestrial
87Sr/86Sr might well be dampened by the 0.7092 marine
ratio.
In sum, values above 0.709 are typical of Norway,
and higher values are not unusual. At the same
time, however, there are—as noted above—places,
such as Hemsedal, with mafic bedrocks with modern
fauna values as low as 0.7051 (Frei et al. 2009). The
range of strontium isotope values within Norway
standard deviation for the 16 pig bones was 0.7111 ±
0.002, with a range from 0.7079 to 0.7157. A graph
of these values is shown in Figure 6. It is of course
likely that some of the pigs had been transported
to Bergen from elsewhere, which may account for
the observed variation. The series of similar values
around 0.710 may best represent the local terrestrial
bioavailable signal around the Bergen area, but of
course the diet of the pigs is also an issue. If the
Figure 5. Strontium isotope ratios from faunal and floral sample s from Norway.
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2015 Special Volume 7
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is thus, unusually large. We will revisit the issue of
distinguishing places of origin in Norway at the end
of this section.
Northern and Western Isles. The northern and
western islands of Britain—the Orkneys, Shetlands,
and Hebrides—have varying but generally older
rocks and higher 87Sr/86Sr values. The following discussion
includes both the geological and bioavailable
sources of strontium isotopes.
The Orkneys, a group of some 70 small islands
just 16 km off the northeast coast of Scotland, are
composed primarily of Palaeozoic (Devonian) sandstones
and flagstones (Fig. 7). Evans et al. (2010)
predicted bioavailable values of ~0.712–0.713 for
these sandstones in Britain. We have also measured
samples from the Orkneys. Four archaeological
faunal teeth produced values between 0.7104 and
0.7106. Four samples of modern fauna and flora
from the mainland and Rondalsay had values between
0.7094 and 07108. A single sample of modern
barley, said to be from Orkney, had a high value of
0.7122.
Montgomery et al. 2014 (this volume) reported
an analysis of archaeological humans, fauna, and
modern plants for the site of Westness on the Orkneys.
Measurement of modern plant and grain
samples produced values between ~0.709 and 0.710.
A number of human burials from Orkney also document
a range of 0.709–0.710 as the baseline value for
these islands (Montgomery et al. 2014 [this volume],
Toolis et al. 2008). As Montgomery (2010) points
out, a combination of high amounts of rainfall, sea
spray, fertilization practices using seaweed, and agricultural
fields in marine sands along the coast can
introduce sufficient strontium of marine origin into
soils and plants to significantly dampen bioavailable
and human ratios towards seawater strontium ratio.
The Shetland Islands lie about 97 km north of
the Orkneys and 360 km west of Bergen, Norway.
The earliest evidence of settlement dates to the
Mesolithic period, ca. 4300 BC (Noble et al. 2008).
The Vikings arrived on Shetland during the late 8th
and 9th centuries, and the island soon became a base
for raids on England and Scotland. The Shetlands
belonged to Norwegian and Danish kings until ca.
AD 1470 (Barrett 2008).
The geology of Shetland is complex with numerous
faults and fold axes throughout a large and
diverse range of bedrock—e.g., metasedimentary,
metavolcanic, and metagranitoid of various ages.
These islands are the northern outpost of the Caledonian
orogeny and contain outcrops of Lewisian,
Dalriadan, and Moine metamorphic rocks with
similar histories to their equivalents on the Scottish
mainland (Gillen 2003). Similarly as well, there are
Old Red Sandstone deposits and granite intrusions.
Glaciations entirely covered the islands and left
deposits of moraine and outwash. These rocks types
should have generally high strontium isotope ratios
concomitant with their age and composition. For
Figure 6. Bar graph of ranked 87Sr/86Sr values for the Bergen pigs.
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2015 Special Volume 7
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example, Jones et al. (2007) report basement rocks
on the Shetlands at 0.735 and sources of steatite
ranging from 0.710 to 0.722.
Evans et al. (2012) reported 4 measurements of
plants and soil extracts from coastal areas of Machair
vegetation on the Shetlands. These values average
0.70937 ± 0.0001, reflecting the effects of sea
spray and rainfall on local geological baseline values.
Much of the human occupation appears to have
focused on these same coastal areas and similar values
should be expected for human tooth enamel. Frei
et al. (2009) have reported 87Sr/86Sr from 5 samples
of sheep wool and 4 samples of soil from several
localities on the Shetlands ranging from 0.7095 to
0.7118; those soil leachates and wool samples show
similar values. Some of these values may be biased
by the location of sample sites near the coast and the
reported use of seaweed for fodder for these animals.
Figure 7. The geology of the Orkney Islands.
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Scotland. The geology of mainland Scotland
is highly varied with 3 main sub-divisions: the
Highlands and Islands are a diverse region to the
north and west, the Central Lowlands comprise a
rift valley primarily of Paleozoic formations, and
the Southern Uplands are largely composed of Silurian
deposits. The bedrock includes ancient Archean
gneiss, metamorphic beds interspersed with granite
intrusions created during the Caledonian mountainbuilding
period, and the remains of substantial tertiary
volcanoes. There is very little information on
bioavailable strontium isotope ratios from this area.
Pankhurst (1969) reported values for the Caledonian
Basin Igneous Province in northeastern Scotland.
Measurements of 87Sr/86Sr on whole rock varied
considerably across this area, with the younger
gabbro-syenites ranging from 0.703 to 0.712 and the
older gneisses and corderites ranging from 0.719 to
0.743. The older rocks are predominant around the
coastal region where Viking settlement might be expected.
The densest settlements of Vikings occurred
around Caithness, with Strathoykel as the southern
frontier. Recent archaeological investigations
are turning up numerous finds around Caithness,
and at the site at the Udal in North Uist (Crawford
1996, Crawford and Switsur 1977). The majority
of settlement in Scotland was in the Western Isles
and the West Highland seaboard (Ritchie 1993). On
mainland Scotland, Viking settlement tended to be
mainly in narrow coastal areas of the southwest, the
west, and the extreme north (Fig. 8).
Degryse et al. (2010) reported rock and plant values
associated with various rock types in Scotland
(Table 1). Rock values exhibit a huge range of variation,
between 0.7028 and 0.7288, with an average
of 0.7106 ± 0.0079. Plants growing on these rocks
range only from 0.7081 to 0.7129 with an average of
0.7097 ± 0.0011. No relationship between plant and
rock values was found, likely due in part to the fact
The introduction of marine strontium via rainfall,
sea spray, and diet should also have the effect of
moving values in human tooth enamel toward the
87Sr/86Sr value of 0.7092 for seawater.
The Outer Hebrides, among the Western Isles
of Scotland, were home to a number of Viking settlements.
This area contains some of the oldest and
youngest rocks in Scotland, from ancient Lewisian
gneisses to 60-Ma volcanics. The Precambrian
Lewisian gneisses represent the oldest rocks in
Britain and date back to around 2.6 billion years
ago. The ancient Lewisian gneisses also encompass
metamorphic rocks such as quartzites, marbles,
graphitic schists, and amphibolites, which are
thought to have originally been sedimentary and
volcanic rocks. These formations make up most of
the Outer Hebrides.
Montgomery et al. (2003) and Montgomery and
Evans (2006) measured values averaging 0.709 from
a Norse graveyard on the Isle of Lewis in the Hebrides.
They concluded that one male, with an enamel
value around 0.707, had probably migrated to Lewis
from within the North Atlantic Tertiary Volcanic
Province (e.g., the small Scottish islands of Skye,
Mull, Canna, Eigg). Moorbath and Walker (1965)
report whole rock 87Sr/86Sr values of 0.705–0.706 for
the basic volcanic rocks of Skye. Pankhurst (1969)
on the other hand, measured a dolerite sample from
Skye with values ranging 0.7045–0.7053.
The island of Skye in the Hebrides has been the
focus of a detailed study of bioavailable 87Sr/86Sr
(Evans et al. 2009). The geology of the island is unusual,
dominated by the remains of a volcanic core
that was active 70 Ma ago. The central mountains
on the island are composed of the granitic Red Hill
and the gabbroic Black Cuillin, the remains of unerupted
magmas and magma chamber contents. The
northern part of Skye is covered by lavas on top of
older Jurassic deposits, which are exposed along the
northeast coast of the island. In the south of Skye,
the basement rocks on which the volcanoes formed
are exposed include parts of the Lewisian Complex,
an ancient gneissic formation from 2800 Ma ago, as
well as sedimentary sequences from 1000 Ma ago
and outcrops of Cambrian Limestone.
Evans et al. (2009) measured some 44 samples
of modern plants, water, snails, and bone from different
parts of the island. The plant samples were
most numerous and showed a wide range of values,
0.7050–0.7200, averaging 0.7108. The snails
and bone showed a much smaller range of values,
0.7089–0.7101, with an average value of 0.7085 for
the animal bone and 0.7094 for the snails. Evans et
al. (2009) used this information and the distribution
of values to construct a bioavailable strontium isotope
map for the Isle of Skye.
Table 1. Analytical results for strontium ratios of plants and rock
in Scotland (Degryse et al. 2010).
Plant Bedrock Rock 87Sr/86Sr Plant 87Sr/86Sr
Bracken Granofelsic schist 0.7288 0.7103
Bracken Basaltic lava 0.7039 0.7081
Bracken Granodiorite 0.7084 0.7095
Bracken Granofelsic schist 0.7208 0.7129
Bracken Diorite 0.7052 0.7090
Bracken Metalimestone 0.7079 0.7090
Bracken Gabbro 0.7036 0.7091
Bracken Basaltic lava 0.7072 0.7092
Bracken Craignurite basalt 0.7061 0.7097
Bracken Basaltic lava 0.7095 0.7094
Heather Conglomerate 0.7152 0.7095
Average 0.7106 0.7097
St. dev. 0.0079 0.0011
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older, harder rocks with a generally higher relief
in the northwest. Pleistocene glaciers left major
changes on the landscape with extensive deposits
of moraine, till, and other features associated with
continental ice sheets.
In Great Britain, soil leach values suggest labile
87Sr/86Sr variations among soils overlying sedimentary
rocks from about 0.7073 on Cretaceous chalk
to 0.7115 on Triassic sandstone (Budd et al. 2000).
Soils formed on igneous and metamorphic rocks as
well as rubidium-rich clay soils are likely to have far
higher ratios. Scotland, the Northern Isles, and parts
of County Antrim have varying but generally higher
87Sr/86Sr values (Evans et al. 2010).
Evans et al. (2010) provided bioavailable strontium
isotope data from modern plants across Britain,
which show a general trend toward values ranging
0.707–0.712 in the south and east, 0.711–0.713 in
the west, and 0.712–0.720 in the north. The result of
their study is a first-approximation strontium isotope
isobar map of Britain (Fig. 9). Montgomery et al.
(2009) report a wide range of 87Sr/86Sr for mineralwater
samples from across the UK, ranging between
0.7059 from Carboniferous volcanic rock sources
and 0.7207 from Precambrian metamorphic rock in
eastern Scotland. The waters from older rocks exhibit
a more radiogenic signature than
those from younger rocks. These studies
provide a reasonably good introduction
to strontium isotope ratios in
Britain and Ireland, and for that reason,
only a brief summary of UK strontium
isotope ratios is presented here.
A number of studies of archaeological
human and faunal remains have been
published over the last decade or so,
providing additional useful information
on variation in 87Sr/86Sr values in
England (e.g., Buckberry et al 2014;
Budd et al. 2000; Eckardt et al. 2009;
Evans et al. 2006; Jay et al. 2013; Kendall
et al. 2013; Montgomery et al. 2003,
2006, 2007a, 2007b, 2009, 2010). Budd
et al. (2000) reported human enamel
values from Anglo-Saxon England
ranging from 0.708 to 0.712. Leach et
al. (2009) determined values from 50
samples from a Roman cemetery at
York. The distribution of values clearly
shows a number of non-local individuals,
while local individuals from York
would appear to average approximately
0.7098 ± 0.0003. The large number of
human proveniencing studies in Britain
that the plants analyzed in that report were epiphytes
and so obtained most of their nutrients and water
from the air. Nevertheless, the information provides
some indication of both geological and bioavailable
87Sr/86Sr values in a small part of western Scotland.
The study also provides an object lesson in the
importance of measuring bioavailable strontium
isotope levels.
England. Viking settlers in the British Isles came
primarily from Norway and Denmark and settled in
the northern half of England, the northern coasts of
Scotland, the Isle of Man, and a variety of locations
throughout Ireland (Fig. 8; Ritchie 1993). Viking settlement
in England was concentrated in the regions
of the East of England, the East Midlands, Yorkshire
and the Umber, and the Northeast and Northwest. In
Scotland, the Norse settled along the west and northern
coasts and on the Northern and Western Isles.
In Ireland, the Vikings have been found in Northern
Ireland and around the modern cities of Dublin, Waterford,
Wexford, Cork, and Limerick.
The geology of England is mainly sedimentary.
The age of the rocks is youngest in the southeast
around London and becomes older in a northwesterly
direction. In general terms, there are younger,
softer, and lower-lying rocks in the southeast and
Figure 8. The distribution of Viking settlement in the UK and Ireland.
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Figure 9. A first approximation strontium isotope map of Britain (Evans et al. 2010).
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provides substantial information on isotopic variation
in the UK.
Isle of Man. The Isle of Man in the Irish Sea is 52
km north to south and 22 km at its widest point east
to west. The highest point on the island is Snaefell,
with a height of 620 m. Hills in the north and south
are separated by a central valley. The complex bedrock
geology of the island is made up of a variety
of formations from a range of geological periods.
A greatly condensed description of the geology of
the island is presented in the following paragraphs,
followed by a discussion of its strontium isotope
landscape. The major bedrock groups are indicated
in Figure 10 and described below. The primary
literature for this summary of the geology comes
from Ford et al. (2001), Kendall (1894), Lamplugh
(1903), and Lewis (1894).
The majority of the Isle of Man is made up of
highly faulted, folded, and slightly metamorphosed
sedimentary rocks collectively known as the Manx
Group, composed largely of dark grey slates. This
predominant feature comprises the island’s central
ridge of slate and greywacke, deposited as sediments
on the ocean floor during the Ordovician ~490–470
Ma ago. There is a belt of younger Silurian sandstones
along the west coast (Dalby Group) and a small area
of reddish Devonian sandstones to the north around
Peel (Peel Sandstone). Limestones in the south of the
island (Castletown Limestone) were formed in the
Carboniferous period, some 330 Ma ago.
The bedrock geology of the Isle of Man is largely
visible only in natural cuts and sections and at higher
elevations. Elsewhere glacial deposits from the
Pleistocene cover the landscape. In addition, outwash
materials left by meltwater from the glaciers
and alluvial fans composed of sediment washed
down from the mountains during summer thaws are
common. The northern quarter of the island is composed
of a deposit of glacial
till (Deep Glacial Till), deeply
burying underlying bedrock.
Some of this material includes
rock pushed by the ice from
the mountains of Scotland and
from the floor of the Irish
Sea. In general, the glacial ice
bulldozed the entire the island
and generally homogenized its
surface. The glacial deposits
make up the agricultural soils
in the cultivated areas of the island,
whereas exposed bedrock
appears at higher elevations.
Marl and lime have been added
to these soils in some areas to
improve growing conditions,
and seaweed is sometimes used
as fertilizer in coastal areas.
In sum, the geology of
Manx is dominated by deposits
of sedimentary rocks, largely
from the Paleozoic period. A
mantle of glacial till and outwash
deposits covers most of
the lower and mid-range elevations
of the island. The boulder
clay, sands, and clays of these
deposits provide the nutrients
for the plants, animals, and
humans that have inhabited the
island for thousands of years
and exhibit a range of stron-
Figure 10. Simplified geology of the Isle of Man and the location of archaeological tium isotope ratios.
sites and baseline sample locations mentioned in the text.
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Some information is available on 87Sr/86Sr from
whole-rock analyses. For example, Evans’ (1989)
measurements on slates in Wales, similar to and contemporaneous
with the Manx Group, yielded values
ranging from 0.728 to 0.773, consistent with the
high rubidium content of such rocks. Groundwater
values, which should be closer to biological available
Sr ratios, tend to be much lower. Shand et al.
(2007, 2009) measured groundwater values in the
same Welsh slates and found values that increased
with depth. The highest water values (0.7115) were
attributed to dissolution of high-strontium minerals
whereas the lowest, surficial values (0.7093)
matched that of current rainwater, which in turn
was attributed to deposition from modern seawater.
Montgomery et al. (2006) likewise measured
0.7139 in groundwater from an Ordovician slate
aquifer in adjacent Cambria. Evans et al. (2010)
mapped the bioavailable value for the Isle of Man as
0.711–0.712. Expected strontium isotope ratios for
Carboniferous seawater, and the Castletown Limestone
deposits, range from approximately 0.7075 to
0.7085 (Shields 2007, Vezier 1989).
We have measured the bioavailable strontium
isotope ratio at a number of locations on the island,
using faunal remains and snail shells to measure the
ratio and determine local baseline values. These data
are presented in Table 2. The 16 87Sr/86Sr values show
a relatively tight distribution with a mean of 0.7089,
a standard deviation of ±0.0004, a minimum value
of 0.7080, and a maximum value of 0.7095. These
values help define the range of bioavailable strontium
isotope ratios on the island. Empirically, we
failed to find high values as reported by Evans et al.
(2010), probably due to the fact that the Manx Group
rocks are highly radiogenic because they have high
Rb/Sr and thus relatively low Sr, in which case any
marine influence will be disproportionately large.
There may also be a contribution of lower 87Sr/86Sr
values from carbonates in local limestone deposits.
The impacts of sea spray and seafood, however, do
not appear to have been significant in the case of the
Isle of Man. Values for local terrestrial bioavailable
strontium isotope ratios are substantially below the
0.7092 value of ocean water and many of the human
enamel values are substantially higher than 0.7092.
Ireland. The geology of Ireland is complex
and consists, at the base, of the remains of ancient
mountain ranges with heavily folded crystalline
and metamorphic rocks (Holland 1981, Woodcock
2000). These rock formations are exposed as the
hills and mountains of the north and the west of the
island (Fig. 11). About 600 million years ago, Ireland
lay under the ocean somewhere in the southern
hemisphere. About 510 million years ago, the land
began to form due to crustal movement, and the part
of the earth’s crust that became Ireland migrated
northwards towards its present location. The rocks,
particularly in the north of the country, are of substantial
age and likely to have quite high strontium
isotope ratios.
The island had a sizable landmass about 340 million
years ago, but after tens of millions of years,
much of the land was worn away and largely covered
by the sea again (Woodcock 1994). Mud rich in the
remains of sea-life was deposited on the floor of this
sea and gradually formed carboniferous limestone,
which covers a large section of Ireland today. With
further crustal movement, the limestone cover was
thrust upwards approximately 300 million years
ago. Limestone deposits are found in limited areas,
largely in the west and southwest of Ireland. These
marine sediments will have radiogenic strontium
isotope values closer to modern seawater, in which
87Sr/86Sr values are ~0.709 (Burke et al. 1982, McArthur
et al. 2001, Veizer 1989).
Jurassic clays were deposited on
top of the Carboniferous limestone
and lie beneath the subsequent Cretaceous
limestone deposits and basalts
that form the landscape today. The
Cretaceous limestone has largely
been eroded from most of Ireland, but
survives in County Antrim because
the area was covered by lava flows
near the beginning of the Tertiary period
(Mitchell 2004).
The lavas known as the Antrim Basalts
form a major part of northeast
Ireland and most of County Antrim,
visible from the River Bann east to
the Antrim coast (Mitchell 2004).
These Tertiary igneous volcanic rocks
Table 2. Baseline samples for strontium and oxygen isotope ratios on the Isle of Man.
Lab No Location Sample Material 87Sr/86Sr δ13C δ18O
F4168 Close ny Chollagh Animal Bone 0.709509 -10.40 -3.98
F5208 Peel Castle Animal Bone 0.709262
F4174 Peel Castle Animal, cat? Bone 0.709072 -13.01 -3.63
F4174 Peel Castle Animal, cat? Bone 0.709072 -13.01 -3.63
F4175 Castle Rushen Animal Bone 0.709099
F5206 Castle Rushen Animal Bone 0.709092
F4175 Castle Rushen Animal Bone 0.709099
F4176 Castle Rushen Animal Bone 0.708705 -11.64 -4.65
F5207 Rushen Abbey Animal Bone 0.708726
F4176 Castle Rushen Animal Bone 0.708705 -11.64 -4.65
F6835 Port Douglas Snail Shell 0.708320
F6836 Ballaugh Snail Shell 0.709090
F6837 Knock-e-dooney Snail Shell 0.708320
F4171 Balladoole Animal Bone 0.709164 -8.95 -2.48
F5209 Balladoole Animal Bone 0.709171
F6838 Balladoole Snail Shell 0.708040
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are part of the British Tertiary Igneous Province
made up of several extrusive plateau basalts which
are relatively young and low in rubidium (Wallace
et al. 1994). O’Connor (1988) reports strontium isotope
ratios ranging from 0.7044 ± 0.0001 to 0.7062
± 0.0009 for 50 rock samples from different components
of the Antrim Basalts.
Glacial moraines, deposited during the Pleistocene
cover virtually all of Ireland, though are less
obvious in Northern Ireland (McCabe 2007). Some
of the glaciated lowlands of Ireland have moraine
deposits over 30 m thick and form a landscape
independent of the rock formations buried deeply
beneath the ground (Clayton 1963, Geikie 1910).
The material in the glacial moraine likely originated
in part from the rocky structures of Ireland as the ice
passed over the land surface and in part as detritus
from the sea floor and Scandinavia transported
by the ice. Thus, the bedrock geology of much of
Ireland, including the Dublin region, is not a good
guide to bioavailable strontium isotope ratios.
A major Viking settlement is known from Dublin
where the deeply buried bedrock consists primarily
of marine basin facies and argillaceous and cherty
limestone and shale that formed during the late Paleozoic
(Geological Survey of Ireland 2009). Knudson
et al. (2012) reported bioavailable values in 11
pig bones from Viking Age excavation in Dublin averaging
0.7094 ± 0003. Measurement of 11 samples
of human tooth enamel from the same site produced
an average value of 0.71017 ± 0.00074. Montgomery
et al. (2014 [this volume]) measured values on
several Viking Age skeletons from Dublin in the
range of 0.709—0.720 and a bioavailable baseline in
the same range as Knudson et al.’s (2012) findings.
In general, these radiogenic strontium isotope data
Figure 11. Geology of Ireland (Geological Survey of Ireland).
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T.D. Price, K.M. Frei, and E. Nauman
2015 Special Volume 7
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are consistent with other archaeological bone data
from Ireland. We have measured archaeological human
bone from Waterford on the southeastern coast
of Ireland, with a mean 87Sr/86Sr of 0.7098 ± 0.0002
(n = 3), and from Tintern Abbey, also on the southeastern
coast of Ireland, where the mean 87Sr/86Sr
was also 0.7098 ± 0.0002 (n = 5). Similarly, archaeological
human bone from Armagh in northeastern
Ireland exhibited a mean 87Sr/86Sr = 0.7094 ± 0.0004
(n = 3). However, at Dunmisk in Northern Ireland,
mean 87Sr/86Sr was somewhat higher at 0.7113 ±
0.0001 (n = 3).
Faroe Islands. The Faroe Islands, part of the
mid-Atlantic ridge, consist of a 3000-m-thick series
of basaltic lavas of Paleocene age divided into
5 major series of flows. These basalts are covered
by a thin layer of moraine and peat on the surface
(Rasmussen and Noe-Nygaard 1970). Dark soils
developed on these typical basaltic bedrocks from
the Tertiary magmatic province of the North Atlantic
realm have very low whole-rock 87Sr/86Sr values between
0.7020 and 0.7035 (Holm et al. 2001). However,
Frei et al. (2009) have reported 87Sr/86Sr values
from 4 sheep-wool samples and 1 soil sample from
the small island of Koltur on the Faroes that fall in
a narrow range from 0.7072 to 0.7087, with good
correspondence between the soil and sheep wool,
reflecting the influence of sea spray in the strontium
isotope values.
We have measured both human and archaeological
fauna from the Faroes. The human tooth enamel
comes from Medieval burials from 2 sites (Sandoy
and Kirkjubør). The 12 human samples have virtually
identical ranges and average 0.7094 ± 0.0006.
Four samples of cattle bone averaged 0.7089 ±
0.0001. We also measured 4 tooth and bone samples
from archaeological sheep and obtained a mean of
0.7090±0.0001. The slightly higher human values
may be in part a consequence of marine foods in
the diet along with a few immigrants in the sample.
Sea spray must have played a large role in raising
strontium isotope values from an expected range
of 0.7020-0.7035 for mid-Atlantic basalts like the
Faroes and Iceland.
Iceland. Iceland is composed of some of the newest
land on earth—basalts that continue to erupt from
the Mid-Atlantic Ridge (Fig. 12). Strontium isotope
ratios for Iceland, estimated from the age and composition
of the basalt, suggest a value between 0.703
and 0.704. Measured ratios on geological formations
at different locations in Iceland confirm this value as
the best estimate for the island bedrock as a whole
(e.g., Dickin 1997; Schilling 1973; Sun and Jahn
1979; Taylor et al. 1998; Wood et al. 1979a, b).
However, strontium isotope ratios measured
in enamel of modern sheep teeth originating from
various locations in Iceland—Jadar, Heggstadanes
(north), Bru ́, Biskupstungur (south), Ormarsstadir,
Fellum (east) and Kjo ́afell, Kjo ́s (west)—range
between 0.7059 and 0.7069 (Price and Gestsdóttir
2006) and are considerably higher than the reported
geological values for Iceland. Archaeological cattle
(2) and pig (1) from northern Iceland average 0.7042.
Data for these fauna are presented in Table 3. We
have also measured modern barley from Iceland and
obtained a value of 0.7068. Juvenile redshank birds
born on Iceland have an average 87Sr/86Sr of 0.7057 ±
0.008 (n = 5; Evans and Bullman 2009), also reflecting
bioavailable strontium levels. In addition, Åberg
(1995) reports a value of 0.706 from a reindeer on
Iceland as intermediate between grass growing on
volcanic soil with a 87Sr/86Sr value between 0.703
and 0.704, and seawater at 0.7092.
We obtained δ13C ratios for the sheep tooth enamel
from our baseline sample in order to check if the
sheep were eating seaweed. Seaweed would have the
value of seawater and might have raised their strontium
isotope ratios and explained the differences
between geological and bioavailable 87Sr/86Sr. Marie
Balasse kindly carried out these measurements, and
the data (Table 4) shows no evidence of marine food
consumption. The farmers who kept these sheep
stated that they were not fed seaweed and the sheep
were all grazed in inland areas, which also reduces
the likelihood of access to seaweed.
Clearly, bioavailable strontium isotope ratios are
higher than values reported for whole rock in Iceland.
The reason for this offset likely relates to the effects
of sea spray over large parts of the island. Ocean water
has an of 0.7092 and sea spray, depositing minerals
from the seawater, raised the bioavailable values
in domestic animals and humans. Marine foods in human
diets are another source of variability in 87Sr/86Sr
in human tooth enamel, discussed in more detail in
Price and Gestsdóttir (in press [this volume]).
Table 3. Strontium isotope ratios on modern and archaeological
fauna from Iceland.
Species Material Context 87Sr/86Sr
Sus Archaeological Enamel HRH 429 0.7044
Bos Archaeological Enamel HRH 003 0.7042
Bos Archaeological Enamel HRH 90 0.7042
Ovis Modern Enamel Bru, Biskupst, 0.7061
Sudurland
Ovis Modern Enamel Kioafell, Kjos, 0.7064
Vesturland
Ovis Modern Enamel Ormsstathir, Eithahr 0.7059
Ovis Modern Enamel Jaoar, Heggstaoanes, 0.7070
Nordurland
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Greenland. Greenland has a very old geology,
dominated by the crystalline rocks of the Precambrian
shield, formed during a succession of Archaean
and early Proterozoic orogenic events that stabilized
as a part of the Laurentian shield about 1600 Ma ago.
Subsequent geological developments mainly took
place along the margins of the shield and involved
the formation of major sedimentary basins largely
in the northern parts of the island. Upper Palaeozoic
and Mesozoic sedimentary basins developed along
the continent–ocean margins in North, East, and
West Greenland and are now preserved both onshore
and offshore. During the Quaternary, Greenland was
almost completely covered by ice sheets.
The areas of the Eastern and Western Norse
settlements on Greenland (black dots in Fig. 13)
are dominated by Precambrian rocks constituting
the Proterozoic and the Archaean craton (Kalsbeek
1997, Moorbath and Pankhurst 1976). The Western
Settlement, near Nuuq, lies in an Archaean part of
the craton, where some of the oldest rocks on Earth
are found. The Eastern settlement is located on
Proterozoic rocks of the Gardar province in southernmost
Greenland, composed of Paleoproterozoic
metamorphic intrusive and metamporphic rock sequences.
Because of the varied geological terrains,
there is of course substantial variation in whole-rock
87Sr/86Sr values and, due the antiquity of the rocks,
these ratios are expected to be generally high. For
example, Blaxlund et al. (1978) report a range of
values from Gardar Province in southwest Greenland.
Whole-rock granite samples from the region
exhibit 87Sr/86Sr values ranging from 0.840 to 1.369.
Hoppe et al. (2003) estimated Greenland values in
the range between 0.725 and 0.755. Minimum values
for the Disko Bay region were measured at greater
than 0.725 (Kalsbeek and Taylor 1999). Thus, although
there is substantial variation within the geological
formations of Greenland, geological 87Sr/86Sr
values are generally high.
Because of the age of these rocks and the fascination
they hold for geologists, numerous studies of
strontium and lead isotopic ratios have been made
Figure 12. Geology of Iceland.
Table 4. Results of carbon and nitrogen isotope analyses of modern
Icelandic sheep tooth enamel.
Lab No. δ13C VPDB δ18O VPDB
F 1153 A -13.474 -9.548
F 1154 A -14.524 -6.214
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in the last 30 years. Polat et al. (2003), for example,
measured 87Sr/86Sr in 3.7–3.8 Ga pillow basalt in
southwest Greenland and reported an extreme range
of values from 0.715 to 0.906. The lower values
in the range are likely the result of diagenesis by
seawater. In terms of bioavailable values, Nelson et
al. (1986) measured 87Sr/86Sr in both modern and archaeological
reindeer from southwestern Greenland
ranging from 0.737 to 0.758. Archaeological domestic
sheep from the Western Settlement in Godthåbs
Bay contained similar ratios (0.750-0.754; Nelson et
al. 1986).
For the determination of bioavailable isotope ratios,
we took samples of faunal remains from various
places in the Eastern and Western Settlement (Table
5, Fig. 14). A few samples are from farms from where
we also have measured human skeletal samples (E29a
Qassiarsuk, E64 Innoqqussaq). In addition, animal
bones from the farms E60, E74, and E172 have been
included. E60 and E172 are situated on the coast
in the Igaliku fjord region, whereas E74 is situated
inland in Vatnahverfi east of Igaliku fjord. E60 is a
smaller farm with only 6 recorded ruins. Only smallscale
test trenches have been dug here, and there are
no dates from the site. E172 is a middle-sized farm
consisting of 19 recorded ruins. Archaeological excavations
as part of the Vatnahverfi-project show that
the site has been populated from the Landnam to at
least the late 1300s. The Vatnahverfi farm E74 was
a small farm with only very few ruins recorded (Algreen
Møller and Koch Madsen 2005, 2006).
The strontium isotope ratios for these samples
are shown in Figure 15. Wild species include arctic
Figure13. Geological provinces of Greenland outside the ice
sheet. The Eastern Settlement is located in the extreme south
in Gardar Province; the Western Settlement is located in the
Archaean craton near Nuuq on the west coast.
Table 5. 87Sr/86Sr values of Greenland fauna samples.
Lab No. Site No. Species Material 87Sr/86Sr
F1853 E35 Cow Enamel 0.706532
F3900 E29 Cow Enamel 0.707373
F3901 W51 Caribou Enamel 0.761059
F3902 W51 Cow Enamel 0.715070
F5230 E60 Cow PH1 0.713800
F5231 E64 Cow PM 0.712691
F5232 E64 Cow PH1 0.713062
F5233 E74 Cow Enamel 0.715853
F5234 E74 Ptarmigan FEM 0.714931
F5235 E74 Ptarmigan TMT 0.713940
F5236 E74 Cow IN 0.711618
F5237 E74 Cow MTP 0.712040
F5238 E74 Cow TTH 0.712231
F5239 E74 Cow MO 0.713703
F5240 E74 Cow PM 0.712150
F5241 E74 Ptarmigan ULN 0.718776
F5242 E74 Cow MO 0.714511
F5243 E74 Cow TTH 0.712374
F5244 E172 Cow PM 0.713123
F5245 E172 Cow PM 0.712922
F5246 E172 Arctic Fox ULN 0.712565
F5247 E172 Arctic Fox MAN 0.712878
F5248 E172 Arctic Fox TIB 0.713147
F5249 E172 Caribou PM 0.721170
F5250 E172 Cow TIB 0.713294
F5251 E172 Cow PH3 0.712047
F5252 E172 Arctic Fox INN 0.712800
F5253 E172 Cow MO 0.713713
F5254 E172 Arctic Fox TRV 0.712163
F5255 E172 Arctic Fox INN 0.712101
F5256 E172 Caribou SCP 0.712711
F5257 E172 Cow MAN 0.713323
F5258 E172 Cow TTH 0.713482
F5259 E172 Cow MO 0.712583
F5260 E172 Cow IN 0.714534
F5261 E172 Cow MO 0.714627
F5262 E172 Cow IN 0.715075
F5950 GUS Arctic Hare CAL 0.752230
F5951 GUS Arctic Hare CAL 0.753207
F5952 GUS Arctic Hare VER 0.749556
F5953 W54 Arctic Hare MAN 0.749979
F5954 W54 Arctic Hare PEL 0.745319
F5955 W54 Arctic Hare TIB 0.754147
F5956 W51 Arctic Hare SCA 0.717470
F5957 W51 Arctic Hare PEL 0.711137
F5958 W51 Arctic Hare PEL 0.719655
F5959 W48 Arctic Hare MAN 0.757904
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fox, arctic hare, caribou, and ptarmigan. Hare and
caribou show a dramatic range of variation from approximately
0.710 to values above 0.760, consistent
with the known age of the rocks in the region. Arctic
fox and ptarmigan do not show the extreme range of
values seen in hare and caribou.
These values vary between the Eastern and Western
Settlement areas. Recall that the geology of the
Western Settlement is older and should have higher
87Sr/86Sr values. There are 1 caribou and 10 arctic hare
samples from the Western Settlement, and in general
these exhibit very high strontium isotope ratios
(Table 5). The single caribou has an 87Sr/86Sr value
of 0.761. The arctic hare, with 3 exceptions, average
around 0.750. The 3 distinctive exceptions are all
below 0.720 and may be individuals that were feeding
close to the coast and subject to a sea-spray effect.
Examination of the values for fauna in a bar
graph of samples from the Eastern Settlement (Fig.
15) provides further insight on the variation present
in this area. Considering the faunal measurements
from the 4 archaeological sites that we sampled, 3
groups of 87Sr/86Sr values are apparent: low, medium,
and high. The majority of the values in fox and
cattle fall in the middle range, between 0.711 and
0.716. There are 3 very low values between 0.706
and 0.707 that are likely non-local to the Eastern
Settlement. There are no geological values below
0.711 reported from Greenland. These low values
belong to domestic cattle, almost certainly imported
from Iceland. The remaining cattle show a range of
values from 0.71162 to 0.7159, consistent with the
older rocks of the Greenland craton. There is one
cow tooth from the Western Settlement in this group
with a value of 0.7150. A higher value might have
been anticipated for this cow given the sheep data
reported by Nelson et al. (1986) as noted above,
but this animal falls within the range of the Eastern
Settlement cattle. Perhaps it was moved from the
Eastern Settlement to the north.
There are 2 very high values above 0.7165, one
caribou and one ptarmigan, wild animals likely
native to Greenland but perhaps from more inland
areas with higher strontium isotope ratios. Based on
Figure 14. Location of faunal samples from the Eastern Settlement, Greenland.
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2015 Special Volume 7
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the middle range of fauna values, it appears that we
can expect bioavailable 87Sr/86Sr values in the Eastern
Settlement area to be between 0.711 and 0.716,
values which fit reasonably well with expectations
based on geology.
Oxygen baseline
Baseline information on oxygen isotopes is
rather limited in most areas. Althougth there are a
number of measuring stations for δ18O in modern
precipitation around the world, they are in fact rather
far apart. Most projections of δ18O values are just
that, projections or rough estimates. More importantly
for archaeological studies, modern rainfall
isotope ratios are not a reliable proxy for past values.
There is very little information avaliable on oxygen
isotope ratios in the past. Since these ratios are a
proxy for atmospheric temperature and since climate
change has characterized both the near and distant
past, it is essential that records of δ18O distribution
Figure 15. 87Sr/86Sr values from archaeological fauna on Greenland. Blue and red lines indicate the Eastern and Western
settlements respectively.
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through time be established. Such information is not
yet available in most areas.
There is some useful information regarding
oxygen isotopes in the North Atlantic. Generally
speaking, variation in oxygen isotopes is
pronounced in northern latitudes, making the ratio
useful as a proveniencing tool in this region. In addition,
oxygen isotopes have played an important
role in the study of ice cores from Greenland and
the reconstruction of past climate (Dansgaard et al.
1969, Langway 2008).
An important early study of phosphate oxygen
isotope ratios in human teeth was done using human
and faunal remains from the Viking period on Greenland
(Fricke et al. 1995). Figure 16 depicts largescale
variation in phosphate oxygen isotope ratios
in modern precipitation across the North Atlantic.
Values range from -18.0‰ along the west coast of
Greenland, to approximately -7.0‰ in Iceland, to
between -8.0‰ and -6.0‰ in northwest Europe.
Fricke et al. (1995) measured δ18Op in human
tooth enamel from a series of sites in Greenland and
a comparative site in Denmark. Their interests in
oxygen isotopes were largely as a proxy for climate
change, rather than human proveniencing. Nevertheless,
the values they measured provide additional
information on oxygen isotope levels in Greenland
(Fig. 17). The range of values from Greenland is
quite high, and some of the more positive values
from Thjodhilde’s Church likely represent samples
from migrant individuals from Iceland or Scandinavia.
δ18Oen PBD values from the Eastern and Western
Settlements (non-Inuit sites) range from approximately
-8.0‰ to -4.0‰. Values from Risby in Denmark
range from approximately -6.0‰ to -3.4‰.
These values compare well with mean values from
our data from Greenland (-7.7‰ ± 1.88) and Denmark
(-4.3‰ ± 0.74), respectively.
Lecolle (1985) measured the oxygen isotope
composition of modern land snail shells as a proxy
indicator for precipitation and mapped δ18O values
across parts of western Europe, Scandinavia, and
Iceland (Fig. 18). This map indicates values in Iceland
between -8.0‰ and -6.0‰, higher values in
Greenland, and a range of values across western Europe,
with little variation in Denmark and substantial
variation with latitude in Norway.
A more detailed view of oxygen isotopic differences
across northwestern Europe appears as Figure
19 (Hughes et al. 2014). Values on this map range
from -5.0‰ to -11.0‰ and document substantial
variation from west to east across Ireland and the
Figure 16. Oxygen isotope ratios in the western North Atlantic (after Fricke et al. 1995).
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2015 Special Volume 7
127
British Isles, Scandinavia, and Western Europe.
There are pronounced differences in this homeland
region of the Norse. Values range from -4.0‰ in the
Outer Hebrides to -8.0‰ across parts of England and
Scotland. Of particular import for our study is the
variation along the coast of Norway where values
in precipitation range from -6.0‰ in the south to
greater than -10.0‰ to the north.
It is important to note that most of the southwest
coast of Norway, from Stavanger to Trondheim has
predicted values between -7‰ and -8‰ for annual
precipitation. These values are easily resolvable
with present instrumentation. This variation means
that theoretically it should be possible to distinguish
different areas of the Norwegian coast as homelands
for the migrants using oxygen isotopes. Unfortunately
the similar ranges of δ18O values in southern
Norway and the north of Scotland and Ireland means
that this ratio will not be useful in distinguishing
these 2 regions.
Another more recent map of oxygen isotope
distribution across Europe (Bowen 2012) provides
a somewhat different picture (Fig. 20). Details of
this mapping procedure to produce “isoscapes” is
provided in Bowen and Revenaugh (2003). In this
depiction, variation in δ18O across northwestern
Europe is less pronounced, and differences range
from -8.0‰ to -15.0‰ from southern England to
Figure 17. Oxygen isotope ratios
from Viking Greenland and
Denmark (Fricke et al. 1995).
Figure 18.
Oxygen isotope
ratios
from Western
Europe
( L e c o l l e
1985).
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T.D. Price, K.M. Frei, and E. Nauman
2015 Special Volume 7
128
northern Norway. Again, however, substantial similarities
between the northern British Isles and southern
Norway are observed.
Somewhat more detailed distribution maps of
modern δ18O are available for a few countries. Figure
21 shows the isoscape for average annual precipitation
for Sweden, with a range from slightly
less than -8.0‰ to -14.0‰ in the northern parts of
the country (Burgman et al.1987). A similar map
is also available for the UK and Ireland (Toolis et
al. 2008), documenting a range from -5.0‰ in the
west to -8.0‰ in the eastern part of the country
(Fig. 22).
At the same time it is important to remember
that these maps of geographic variation in oxygen
isotope values are models, estimates of the distribution
of δ18O across space, and based on modern
precipitation or ground water measurements. There
have been few detailed, systematic attempts to map
δ18O and most maps/models are based on very few
data points. There are substantial differences for
the same areas among the various models. It is not
realistic to assume that archaeological materials will
consistently fit modern models. In addition, there are
significant other problems with oxygen isotopes and
proveniencing.
In addition to maps of modern δ18O distribution
across Europe, there are also several bioarchaeological
studies of past human remains. For example,
Chenery et al. (2011) report oxygen isotope
ratios of -6‰ to -8‰ from
burials at Catterick, a small
Roman town and minor fort
north of York. Eckhardt et al.
(2009) in a study of Roman
burials from Winchester in
the south of England suggest
a range of δ18Op in the entire
UK between -8.7‰ and
-4.7‰. Values from the Winchester
enamel cover most
of that range. Lamb et al.
(2012) found oxygen isotope
ratios averaging -7.3‰ ± 1.5
for a medieval graveyard in
southeastern Scotland.
Evans et al. (2012) summarized
strontium and oxygen
isotope variation in
archaeological human tooth
enamel excavated in Britain.
The strontium isotope
ratios range between 0.7078
and 0.7165 (excluding individuals
thought to be of
non-British origin). The oxygen
isotope data is normally
distributed with a mean of
approximately -7.1‰ ± 0.5.
Two sub-populations have
been identified that provide
different baseline averages
for human enamel values:
-7.5‰ ± 1.8 (2 s.d.) from
the eastern side of Britain
where there are lower rainfall
levels, and -5.8‰ ± 1.8.
from the western part of Britain
where rainfall levels are
higher.
Fig. 19. Isoscape map of mean annual δ18O values for precipitation in western Europe
(Hughes et al. 2014).
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2015 Special Volume 7
129
Knudson et al. (2012) in their study of Viking
burials in Dublin reported δ18O values between -7‰
and -17‰ with an average of -7.2‰ from a sample
of 12 individuals. Montgomery et al. (2014 [this volume])
reported δ18O for Dublin as averaging around
-8.0‰, based on the analysis of several Viking Age
skeletons. Similar samples from the Westness cemetery
on Orkney exhibit δ18O values between -10.0‰
and -7.0‰. Darling et al. (2003) reported surfacewater
values in the Shetlands averaging -6.1‰.
Average values for δ18O from several studies
in northwestern Europe document jslightly lower
values across the region. In Scandinavia, oxygen
isotopes in the enamel of the local inhabitants of
the Viking Age cemetery at Trelleborg in Denmark
averaged -4.54‰ ± 0.5 (Price et al. 2011). δ18O from
Figure 20. Average annual δ18O in precipitation in modern Europe (Bowen 2012).
Journal of the North Atlantic
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2015 Special Volume 7
130
20 burials at Fräslegården in Falbygden region of
central Sweden (Sjögren et al. 2009) have a mean
value of -4.4‰ ± 0.90. Fourteen samples from the
medieval cemetery at Bryggen, Norway, produce a
mean δ18O of -4.27‰ ± 0.7. Ireland exhibits somewhat
different values.
We have summarized a substantial series of
measurements in Table 6 to provide average and
standard deviation for oxygen isotope values from
archaeological humans in 6 areas for comparison.
We have attempted to screen these samples for local
individuals and remove non-locals (indicated by
the condition column). There is surprisingly little
variation among these areas in mean δ18O, with the
exception of Greenland and Dublin having distinctly
higher values than Denmark, Norway, Iceland, and
the Faroes. Such data suggest that while oxygen may
provide information on geographic origins in some
cases (e.g., Greenland vs. Iceland or Norway), this
ratio will not be useful in many other situations.
Oxygen remains a very uncertain measure of
geographic variation for several reasons. There are
a number of potential sources of variation. For example,
the consumption of 18O-enriched breast milk
affect the oxygen isotope values in enamel and bone
that formed before and during weaning (e.g., Knudson
2009, Wright and Schwarcz 1998) Variation
within a population is quite high, often more than
Figure 21. Average annual δ18O in precipitation in modern
Sweden (Burgman et al. 1987).
Figure 22. Oxygen isotope ratios in UK water (Toolis et
al. 2008).
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2015 Special Volume 7
131
between geographic regions. Estimates of oxygen
isotope ratios based on measurement of modern
rainfall or surface water usually fail to correlate with
prehistoric samples. As noted in (Price, in press [this
volume]), there are also the concerns that oxygen
has been measured in both carbonate and phosphate
components of human skeletal tissue and that different
standards have been used (e.g., SMOV, PDB).
δ18O values for carbonate or phosphate oxygen using
different standards are comparable though calculation
(Chenery et al. 2011).
Furthermore, what are presumed to be basic principles
of oxygen isotope variation do not seem to be
followed in some baseline samples. For example, we
measured oxygen isotope ratios in archaeological
beaver from a series of sites along the west coast of
Norway. A plot of δ18O vs. the UTM north coordinates
for the samples is shown in Figure 23. There is
an observable increase in the δ18O values with latitude
north. These data contradict the basic principle
of oxygen isotope variation that ratios should become
more negative inland with elevation and north
or south toward colder air and the polar regions.
The beaver data show a clearly negative correlation
between oxygen isotope ratios and northern latitude,
ratios become more positive as the location of the
samples moves north.
Conclusions
Knowledge of baseline isotopic values is essential
for the investigation of past human mobility.
Fortunately there is a good bit of data now available
to permit the assessment of these values. Based ultimately
on the geology of the region, a basic principle
relates older rocks to higher strontium isotope ratios.
Very old rocks dominate parts of the North Atlantic
region, particularly in Norway, Sweden, Scotland,
Northern Ireland, and Greenland. Very young rocks
are found in Iceland and the Faroes as part of the
expansion of the mid-Atlantic ridge and the volcanic
eruptions that define that phenomenon. Between
these extremes there is a common isotope range between
~0709 and 0.711 that is found in many parts
of northwest Europe, particularly in areas dominated
by glacial and periglacial deposits and coastal regions
where marine foods and sea spray have altered
the geological background.
Because Iceland has a distinctive geology of very
young rock with very low strontium isotope ratios,
the presence of non-local individuals from older terrains
should be quite obvious. In a similar fashion,
individuals from Iceland who move to Greenland
would also have very distinctive strontium isotope
value among the higher 87Sr/86Sr values there.
Greenland has 2 areas of Norse settlement with distinctive
87Sr/86Sr in each area. For this reason, movement
between the Eastern and
Western Settlement should
also be visible in the isotope
data. On the other hand, the
distinction between individuals
in originating in Norway,
northern Britain, and Greenland
using 87Sr/86Sr may be
a difficult undertaking given
the generally higher 87Sr/86Sr
values in these areas.
Oxygen isotopes may provide
some resolution of this
difficulty particularly in separating
individuals from Greenland
with more negative δ18O,
from individuals from Norway
and northern Britain who
should have less-negative values.
On the other hand, as we
have noted, oxygen isotopes
Table 6. Average values for oxygen isotope ratios in selected
countries of Northwest Europe.
Place Condition n Mean sd
Denmark less than 0.711 71 -4.3 0.7
Norway -- 15 -4.4 1.2
Faroe Islands -- 11 -3.4 0.7
Iceland less than 0.709 10 -4.7 1.1
Greenland >0.709 35 -7.7 1.9
Dublin -- 12 -7.2 1.0
Figure 23. Scatterplot of δ18O vs. UTM coordinate north for archaeological beaver
from Norway.
Journal of the North Atlantic
T.D. Price, K.M. Frei, and E. Nauman
2015 Special Volume 7
132
exhibit a good bit of variability and do not always
follow expectations.
Literature Cited
Åberg, G. 1995. The use of natural strontium isotopes as
tracers in environmental studies. Water, Air and Soil
Pollution 29:309–332.
Åberg, G., G. Fosse, and H. Stray. 1998. Man, nutrition
and mobility: A comparison of teeth and bone from the
Medieval era and the present from Pb and Sr isotopes.
The Science of the Total Environment 224:109–119.
Algreen Møller, N., and C. Koch Madsen. 2005. Nordboerne
i Vatnahverfi. Rapport om rekognoscering og
opmåling af nordboruiner i Vatnahverfi, sommeren
2005. SILA Feltrapport nr. 24, Copenhagen, Denmark.
Algreen Møller, N., and C. Koch Madsen. 2006. Gård og
Sæter, Hus og Fold - Vatnahverfi 2006. Rapport om
besigtigelser og opmålinger i Vatnahverfi, sommeren
2006. SILA Feltrapport nr. 25, Copenhagen, Denmark.
Arnórsson, S., and A. Andrésdóttir. 1995. Processes controlling
the distribution of boron and chlorine in natural
waters in Iceland. Geochimica et Cosmochimica
Acta 59:4125–4146.
Barrett, J.H. 2008. The Norse in Scotland. Pp. 411–427,
In Stefan Brink (Ed.). The Viking World. Routledge,
Abingdon, UK.
Beard, B.L., and C.M. Johnson. 2000. Strontium isotope
composition of skeletal material can determine the
birth place and geographic mobility of humans and
animals. Journal of Forensic Science; 45:1049–1061.
Berner, K.B., and Berner, R.A. 1987. The Global Water
Cycle: Geochemistry and Environment. Prentice-Hall,
NY, USA. 397 pp.
Blaxland, A.B., O. van Breemen, C.H. Emeleus, and J.G.
Andersen. 1978. Age and origin of the major syenite
centres in the Gardar province of South Greenland.
Geological Society of America Bulletin 89:231–244.
Boba, I. 1967. Nomads, Northmen, and Slavs: Eastern
Europe in the Ninth Century. Mouton, The Hague,
Netherlands.
Böhlke, J.K., and M. Horan. 2000. Strontium isotope
geochemistry of groundwaters and streams affected
by agriculture, Locust Grove, MD. Applied Geochemistry
15:599–609.
Bowen, G.J. 2012. Gridded maps of the isotopic composition
of meteoric waters. Available on line at http://
www.waterisotopes.org. Accessed 15 May 2012.
Bowen, G.J., and J. Revenaugh. 2003. Interpolating the
isotopic composition of modern meteoric precipitation.
Water Resources Research 39:1299.
Buckberry, J.L., J. Montgomery, N. Neale, and J. Towers.
2014. Finding Vikings in the Danelaw. Oxford Journal
of Archaeology 33:413–434.
Budd, P., J. Montgomery, J. Evans, C. Chenery, and D.
Powlesland. 2000. Reconstructing Anglo-Saxon residential
mobility from O-, Sr- and Pb-isotope analysis.
Geochimica et Cosmochimica Acta 66 (S1):A109.
Burgman, J.O., B. Calles, and F. Westman. 1987. Conclusions
from a ten-year study of oxygen-18 in precipitation
and runoff in Sweden. Pp. 579–590, In Isotope
Techniques in Water Resources Development. International
Atomic Energy Agency, Vienna, Austria.
Burke, W.H., R.E. Denison, E.A. Hetherington, K.B.
Koepnick, H.F. Nelson, and J.B. Otto. 1982. Variation
of seawater 87Sr/86Sr throughout Phanerozoic time.
Geology 10:516–519.
Chadwick, R.A., D.I. Jackson, R.P. Barnes, G.S. Kimbell,
H. Johnson, R.C. Chiverrell, G.S.P. Thomas, N.S.
Jones, N.J. Riley, E.A. Pickett, B. Young, D.W. Holliday,
D.F. Ball, S.G. Molyneux, D. Long, G.M. Power,
and D.H. Roberts. 2001. Geology of the Isle of Man
and its offshore area. British Geological Survey, Nottingham,
UK.
Chenery, C., H. Eckardt, and G. Müldner. 2011. Cosmopolitan
Catterick? Isotopic evidence for population
mobility on Rome’s Northern frontier. Journal of Archaeological
Science 38:1525–1536.
Clayton, K.M., 1963. A map of the drift geology of Great
Britain and Northern Ireland. The Geographical Journal
129:75–81.
Crawford, I.A. 1996. The Udal. Current Archaeology
147:84–94.
Crawford, I.A., and R. Switsur. 1977 Sandscaping and
C14: The Udal, North Uist. Antiquity. Current Archaeology
127:295–297
Dansgaard, W., S.J. Johnsen, J. Moller, and C.C. Langway
Jr. 1969. One thousand centuries of climate record
from Camp Century on the Greenland Ice Sheet. Science
166:377–381.
Darling, W.G., A.H. Bath, and J.C. Talbot. 2003. The O
& H stable isotopic composition of fresh waters in
the British Isles. 2. Surface waters and groundwater.
Hydrology and Earth System Sciences 72:183–195.
Degryse, P., A. Shortland, D. De Muynck, L. Van Heghe,
R. Scott, B. Neyt, and F. Vanhaecke. 2010. Considerations
on the provenance determination of plant ash
glasses using strontium isotopes. Journal of Archaeological
Science 37:3129–3135.
Dickin, A.P. 1997. Radiogenic Isotope Geology. Cambridge
University Press, Cambridge, UK.
Eckardt, H., C. Chenery, P. Booth, J.A. Evans, A. Lamb,
and G. Müldner. 2009. Oxygen and strontium isotope
evidence for mobility in Roman Winchester. Journal of
Archaeological Science 36:2816–2825.
Evans, J.A., 1989. Short paper: A note on Rb–Sr wholerock
ages from cleaved mudrocks in the Welsh
basin. Journal of the Geological Society of London
146:901–904.
Evans, J., and R. Bullman. 2009. 87Sr/86Sr isotope fingerprinting
of Scottish and Icelandic migratory shorebirds.
Applied Geochemistry 24:1927–1933.
Evans, J., N. Stoodley, and C. Chenery. 2006. A strontium
and oxygen isotope assessment of a possible
fourt- century immigrant population in a Hampshire
cemetery, southern England. Journal of Archaeological
Science 33:265–272.
Journal of the North Atlantic
T.D. Price, K.M. Frei, and E. Nauman
2015 Special Volume 7
133
Evans, J.A., J. Montgomery, and G. Wildman. 2009. Isotope
domain mapping of 87Sr/86Sr biosphere variation
on the Isle of Skye, Scotland. Journal of the Geological
Society of London 166:617–631.
Evans, J.A., J. Montgomery, G. Wildman, and N. Boulton.
2010. Spatial variations in biosphere 87Sr/86Sr in
Britain. Journal of the Geological Society, London
167:754–764.
Evans, J.A., C.A. Chenery, and J. Montgomery. 2012. A
summary of strontium and oxygen isotope variation in
archaeological human tooth enamel excavated from
Britain. Journal of Analytical Atomic Spectrometry
27:754–760.
Ford, T.D., D. Burnett, D. Quirk, and J.T. Greensmith.
2001. The Geology of the Isle of Man. Geologists' Association,
London, UK.
Franzen, L.G. 1990. Transport, deposition, and distribution
of marine aerosols over southern Sweden during
dry westerly storms. Ambio 19:180–188.
Fredén, C. (Ed.) 1994. Geology. National Atlas of Sweden.
SNA Publishing, Stockholm, Sweden. 208 pp.
Frei, K.M., and R. Frei. 2011. The geographic distribution
of strontium isotopes in Danish surface waters: A base
for provenance studies in archaeology, hydrology, and
agriculture. Applied Geochemistry 26:326–340.
Frei, K.M., and T.D.Price. 2012. Isotopes and human
mobility in prehistoric Denmark. Journal of Anthropological
and Archaeological Sciences 4:103–114.
Frei, K.M., R. Frei, U. Mannering, M. Gleba, M.B. Nosch,
and H.S. Lyngstrøm. 2009. Provenance of ancient textiles:
A pilot study evaluating the Sr isotope system in
wool. Archaeometry 51:252–276.
Fricke, H.C., J.R. O’Neil, and N. Lynnerup. 1995. Oxygen
isotope composition of human tooth enamel from
medieval Greenland: Linking climate and society.
Geology 23:869–872.
Geikie, A. 1910. Map showing the surface geology of Ireland,
scale 1:633,600. Bartholomew, Dublin, Ireland.
Geological Survey of Ireland. 2009. Bedrock Geology.
Dublin, Ireland.
Gillen, C.. 2003. Geology and Landscapes of Scotland.
Terra Publishing, Harpenden, UK.
Gosz, J.R., and D.I. Moore. 1989. Strontium isotope studies
of atmospheric inputs to forested watersheds in
New Mexico. Biogeochemistry 8:115–134.
Graustein, W.C., and R. Armstrong. 1983. The use of
87Sr/86Sr ratios to measure atmospheric transport into
forested watersheds. Science 219:289–292.
Holland, C.H. 1981. A Geology of Ireland. Scottish Academic
Press, Edinburgh, UK.
Holm, P.M., N. Hald, and R. Waagstein. 2001. Geochemical
and Pb–Sr–Nd isotopic evidence for separate hotdepleted
and Iceland plume mantle sources for the
Paleogene basalts of the Faroe Islands. Chemical
Geology 178:95–125.
Hoppe, K.A., P.L. Koch, and T.T. Furutani. 2003. Assessing
the preservation of biogenic strontium in fossil
bones and tooth enamel. International Journal of Osteoarchaeology
13:20–28.
Hughes, S.S. A.R. Millard, S.J. Lucy, C.A. Chenery, J.A.
Evans, G.Nowell, and D.G. Pearson. 2014. Anglo-
Saxon origins investigated by isotopic analysis of
burials from Berinsfield, Oxfordshire, UK. Journal of
Archaeological Science 42:81–92.
Jay, M., J. Montgomery, O. Nehlich, J. Towers, and J.
Evans. 2013. British Iron Age chariot burials of the
Arras culture: A multi-isotope approach to investigating
mobility levels and subsistence practices. World
Archaeology 45:473–491.
Jones, R.E., V. Kilikoglou, V. Olive, Y. Bassiakos,
R.
Ellam, I.S.J. Bray, and
D.C.W. Sanderson. 2007. A
new protocol for the chemical characterisation of
steatite and two case studies in Europe: The Shetland
Islands and Crete. Journal of Archaeological Science
34:626–641.
Junge, C.E. 1972. Our knowledge on the physico-chemistry
of aerosols in the undisturbed marine environment.
Journal of Geophysical Research 77:5183–5200.
Kalsbeek, F. 1997. Age determination of Precambrian
rocks from Greenland: Past and present. Geology of
Greenland Survey Bulletin 176:55–59.
Kalsbeek, F., and P.N. Taylor. 1999. Review of isotope
data for Precambrian rocks from the Disko Bugt region,
West Greenland. Geology of Greenland Survey
Bulletin 181:41–47.
Kendall, P.F. 1894. On the Glacial Geology of the Isle of
Man. Brown and Son, Printers, Douglas, Isle of Man.
Kendall, E., J. Montgomery, J. Evans, C. Stantis, and V.
Mueller. 2013. Mobility, mortality, and the Middle
Ages: Identification of migrant individuals in a 14thcentury
Black Death cemetery population. American
Journal of Physical Anthropology 150:210–222.
Kettle, A.J., and S.M. Turner. 2007. Upper ocean response
to a summer gale south of Iceland: Importance of sea
spray in the heat and freshwater budgets of storms.
Journal of Geophysical Research 112:1–34.
Knipper, C. 2011. Die räumliche Organisation der linearbandkeramischen
Rinderhaltung: naturwissenschaftliche
und archäologische Untersuchungen. British Archaeological
Reports International Series 2305.
Knudson, K.J., 2009. Oxygen Isotope Analysis in a Land
of Environmental Extremes: The Complexities of
Isotopic Work in the Andes, International Journal of
Osteoarchaeology 19:171–191.
Knudson, K.J., B. O’Donnabhain, C. Carver, R. Cleland,
and T.D. Price. 2012. Migration and Viking Dublin:
Paleomobility and paleodiet through isotopic analyses.
Journal of Archaeological Science 39:308–320.
Lamb, A.L., M. Melikian, R. Ives, and J. Evans. 2012.
Multi-isotope analysis of the population of the lost
medieval village of Auldhame, East Lothian, Scotland.
Journal of Analytical Atomic Spectrometry
27:765–777.
Lamplugh, G.W. 1903. The Geology of the Isle of Man.
London: Wyman and Sons.
Langway, C.C., Jr. 2008. The history of early polar ice
cores. ERDC/DRREL TR-08-1. US Army Corps of
Engineers, Engineer Research and Development Center,
Cool Regions and Engineering Laboratory, Hannover,
NH, USA.
Journal of the North Atlantic
T.D. Price, K.M. Frei, and E. Nauman
2015 Special Volume 7
134
Leach, S., M. Lewis, C. Chenery, H. Eckardt, and G. Müldner.
2009. Migration and Diversity in Roman Britain:
A multidisciplinary approach to the identification of
immigrants in Roman York, England. American Journal
of Physical Anthropology 140:546–561.
Lecolle, P. 1985. The oxygen isotope composition of landsnail
shells as a climatic indicator: Applications to
hydrogeology and paleoclimatology. Chemical Geology
58:157–181.
Lewis, H.C. 1894. Papers and Notes on the Glacial Geology
of Great Britain And Ireland. Longmans, Green,
and Co., London, UK.
Lovett, R.F. 1978. Quantitative measurement of airborne
sea salt in north Atlantic, Tellu, 30:358–364.
Lupker, M., S.M. Aciego, B. Bourdon, J. Schwander, and
T.F. Stocker. 2010. Isotopic tracing (Sr, Nd, U, and Hf)
of continental and marine aerosols in an 18th-century
section of the Dye-3 ice core (Greenland). Earth and
Planetary Science Letters 295:277–286.
Maurer, A.-F., S.J.G. Galer, C.Knipper, L. Beierlein, E.V.
Nunn, D.Peters, T. Tütken, K.W. Alt, and B.R. Schöne.
2012. Bioavailable 87Sr/86Sr in different environmental
samples: Effects of anthropogenic contamination and
implications for isoscapes in past migration studies.
Science of the Total Environment 433:216–229.
McArthur, J.M., R.J. Howarth, and T.R. Bailey. 2001.
Strontium Isotope Stratigraphy: LOWESS Version 3:
Best fit to the marine Sr-isotope curve for 0–509 Ma
and accompanying look-up table for deriving numerical
age. The Journal of Geology 109:155–170.
McCabe, M. 2007. Glacial Geology and Geomorphology:
The Landscapes of Ireland. Dunedin Academic Press,
Edinburgh, UK.
Miller E.K., J.D. Blum, and A.J. Friedland. 1993. Determination
of a soil exchangeable-cation loss and weathering
rates using Sr isotopes. Nature 362:438–441.
Mitchell, W. 2004 The Geology of Northern Ireland: Our
Natural Foundation. Geological Survey of Northern
Ireland, Belfast, Ireland.
Montgomery, J. 2010. Passports from the past: Investigating
human dispersals using strontium isotope
analysis of tooth enamel. Annals of Human Biology
37:325–346.
Montgomery, J., and J.A. Evans. 2006. Immigrants on
the Isle of Lewis: Combining traditional funerary and
modern isotope evidence to investigate social differentiation,
migration and dietary change in the Outer
Hebrides of Scotland. Pp. 122–142, In R. Gowland and
C. Knusel (Ed.). The Social Archaeology of Funerary
Remains. Oxbow Books, Oxford, UK.
Montgomery, J., J.A. Evans, and T. Neighbour. 2003. Sr
isotope evidence for population movement within the
Hebridean Norse community of NW Scotland. Journal
of the Geological Society 160:649–653.
Montgomery, J., J.A. Evans, and G. Wildman. 2006.
87Sr/86Sr isotope composition of bottled British mineral
waters for environmental and forensic purposes.
Applied Geochemistry 21:1626–1634.
Montgomery, J., R.E. Cooper, and J.A. Evans. 2007a. Foragers,
farmers, or foreigners? An assessment of dietary
strontium isotope variation in Middle Neolithic and
Early Bronze Age East Yorkshire. Pp. 65–75, In M.
Larsson and M. Parker Pearson (Eds.). From Stonehenge
to the Baltic: Living with Cultural Diversity in
the Third Millennium BC. BAR International Series
1692. Archaeopress, Oxford, UK.
Montgomery, J., J.A. Evans, and R.E. Cooper. 2007b.
Resolving archaeological populations with Sr-isotope
mixing models. Applied Geochemistry 22:1502–1514.
Montgomery, J., G. Müldner, G. Cook, A. Gledhillan, and
R. Ellam. 2009. Isotope analysis of bone collagen and
tooth enamel. Pp. 65–82, In C. Lowe (Ed.). “Clothing
for thae Soul Divine”: Burials at the Tomb of St Ninian
Excavations at Whithorn Priory 1957–1967. Headland
Archaeology Ltd., Edinburgh, UK.
Montgomery, J., J.A. Evans, S.R. Chenery, V. Pashley, and
K. Killgrove. 2010. “Gleaming, white, and deadly”:
The use of lead to track human exposure and geographic
origins in the Roman period in Britain. Pp.
199–226, In H. Eckardt (Ed.). Diasporas in the Roman
World. Journal of Roman Archaeology Supplement,
Portsmouth, RI, USA.
Montgomery, J., V. Grimes, J. Buckberry, J.A. Evans,
M.P. Richard, and J.H. Barrett. 2014. Finding Vikings
with isotope analysis: The view from wet and windy
islands. Journal of the North Atlantic Special Issue
7:54–70.
Moorbath, S., and R.J. Pankhurst. 1976. Further rubidium-
strontium age and isotope evidence for the nature
of the late Archean plutonic event in West Greenland.
Nature 262:124–126.
Moorbath, S., and G.P.L. Walker. 1965. Strontium isotope
investigation of igneous rocks from Iceland. Nature
207:837–840.
Nelson, B.K., M.J. DeNiro, M.J. Schoeninger, and D.J.
DePaolo. 1986. Effects of diagenesis on strontium,
carbon, nitrogen, and oxygen concentration and isotopic
composition of bone. Geochimica et Cosmochimica
Acta 50:1941–1949.
Neumann, E.-R., G.R. Tilton, and E. Tuen. 1988. Sr, Nd
and Pb isotope geochemistry of the Oslo rift igneous
province, southeast Norway. Geochimica et Cosmochimica
Acta 52:1997–2007.
Noble, G., T. Poller, and L. Verrill. 2008. Scottish Odysseys:
The Archaeology of Islands. Tempus, Stroud,
UK.
Noonan, T.S. 1991. The Vikings and Russia: Some new
directions and approaches to an old problem. Pp.
201–206, In R. Samson (Ed.). Social Approaches to
Viking Studies. Cruithne Press, Glasgow, UK.
Ó Corráin, D. 1997. Ireland, Wales, Man, and the Hebrides.
Pp. 83–109, In P. Sawyer (Ed.). The Oxford
Illustrated History of the Vikings. Oxford University
Press, Oxford, UK.
O’Connor, P.J. 1988. Strontium isotope geochemistry of
Tertiary igneous rocks, NE Ireland. Geological Society,
London, Special Publications 39:361–363.
Journal of the North Atlantic
T.D. Price, K.M. Frei, and E. Nauman
2015 Special Volume 7
135
O’Nions, R.K., and R.J. Pankhurst. 1973. Secular variation
in the Sr isotope composition of Icelandic volcanic
rocks. Earth and Planetary Science Letters 21:12–21.
Pankhurst, R.J. 1969. Strontium isotope studies related to
petrogenesis in the Caledonian basic igneous province
of NE Scotland. Journal of Petrology 10:115–143.
Pidgeon, R.T., and A.M. Hopgood. 1975. Geochronology
of Archaean gneisses and tonalites from north of the
Fredrikshåbs isblink. Geochimica et Cosmochimica
Acta 39:1333–1346.
Polat, A., A.W. Hofmann, C. Munker, M. Regelous, and
P.W.U. Appel. 2003. Contrasting geochemical patterns
in the 3.7–3.8-Ga pillow basalt cores and rims. Isua
Greenstone Belt, southwest Greenland: Implications
for postmagmatic alteration processes. Geochimica et.
Cosmochimica Acta 67:441–457.
Price, T.D. In press. An Introduction to the Isotopic Studies
of Ancient Human Remains. Journal of the North
Atlantic Special Volume 7.
Price, T.D., and H. Gestsdóttir. 2006. The first settlers of
Iceland: An isotopic approach to colonization. Antiquity
80:130–144.
Price, T.D., and H. Gestsdóttir. In press. The peopling of
the North Atlantic: Isotopic results from Iceland. Journal
of the North Atlantic Special Volume 7.
Price, T.D., J.H. Burton, and A.R. Bentley. 2002. The
characterization of biologically available strontium
isotope ratios for the study of prehistoric migration.
Archaeometry 44:117–135.
Price, T.D., K.M. Frei, H. Gestsdottir, and V. Tiesler.
2010. Isotopes and mobility: Case studies with large
samples. Mitteilungen der Berliner Gesellschaft
für Anthropologie, Ethnologie und Urgeschichte
31:203–212.
Price, T.D., K.M. Frei, A. Dobat, N. Lynnerup, and P.
Bennike. 2011. Who was in Harold Bluetooth’s army?
Strontium isotope investigation of the cemetery at the
Viking Age fortress at Trelleborg, Denmark. Antiquity
85:476–489.
Prospero, J.M., D.L. Savlie, R. Arimoto, H.r Olafsson, H.
Hjartarson. 1995. Sources of aerosol nitrate and nonsea-
salt sulfate in the Iceland region. The Science of
the Total Environment 160/161:181–191.
Raiber, M., J.A. Webb, and D.A. Bennetts. 2009. Strontium
isotopes as tracers to delineate aquifer interactions
and the influence of rainfall in the basalt plains
of southeastern Australia. Journal of Hydrology
367:188–199.
Rasmussen, J., and A. Noe-Nygaard. 1970. Geology of the
Faeroe Islands. Danmarks Geologiske Undersøgelse,
Series I, 25. Copenhagen, Denmark.
Ritchie, A. 1993. Viking Scotland. Batsford, London, UK.
Sattouf, M., S. Kratz, K. Diemer, O. Rienitz, J. Fleckenstein,
D. Schiel, and E. Schnug. 2007. Identifying the
origin of rock phosphates and phosphorus fertilizers
through high-precision measurement of the strontium
isotopes 87Sr and 86Sr. Landbauforschung Völkenrode
57:1–11.
Sawyer, P., O. Pritsak, B.E. Hoven, T.S. Noonan, T.
Tuukka, J. Waller, and A. Stalsburg. 1982. Relations
between Scandinavia and the southeastern Baltic/
northeastern Russia in the Viking Age. Journal of Baltic
Studies 13:175–295.
Schilling, G. 1973. The Icelandic mantle plume: Geochemical
study of the Reykjanes Ridge. Nature
242:565–571.
Sealy, J.C., van der Merwe, N.J., Sillen, A., Kruger, F.J.,
and Krueger, H.W., 1991, 87Sr/86Sr as a dietary indicator
in modern and archaeological bone, Journal of
Archaeological Science, 18, 399–416.
Shand, P., D.P.F. Darbyshire, D.C. Gooddy, and A.H. Haria.
2007. 87Sr/86Sr as an indicator of flowpaths and
weathering rates in the Plynlimon experimental catchments,
Wales. UK. Chemical Geology 236:247–265.
Shand, P., D.P.F. Darbyshire, A.J. Love, and W.M.
Edmunds. 2009. Sr isotopes in natural waters: Applications
to source characterisation and water–rock
interaction in contrasting landscapes. Applied Geochemistry
24:574–586.
Shields, G.A. 2007. A normalised seawater strontium isotope
curve: Possible implications for Neoproterozoic-
Cambrian weathering rates and the further oxygenation
of the Earth. eEarth, 2(2):35–42.
Sillen A., G. Hall, S. Richardson, and R. Armstrong. 1998.
87Sr/86Sr ratios in modern and fossil food-webs of the
Sterkfontein Valley: Implications for early hominid
habitat preference. Geochimica et Cosmochimica Acta
62:2463–2473.
Sjögren, K.-G., T.D. Price, and T. Ahlström. 2009.
Megaliths and mobility in southwestern Sweden.
Investigating relations between a local society and
its neighbours using strontium isotopes. Journal of
Anthropological Archaeology 28:85–101.
Stewart, B.W., R.C. Capo, O.A. Chadwick. 2001. Effects
of precipitation on weathering rate, base cation provenance,
and Sr isotope composition in a volcanic soil
climosequence, Hawaii. Geochimica Cosmochimica
Acta, 65:1087–1099.
Sun, S.-S., and B.-M. Jahn. 1975. Lead and strontium
isotopes in post-glacial basalts from Iceland. Nature
255:527–528.
Sveinbjörnsdóttir, Á.E., J. Heinemeier, J. Arneborg, N.
Lynnerup, G. Ólafsson, and G. Zoëga. 2010. Dietary
reconstruction and reservoir correction of 14C dates
on bones from pagan and early Christian graves in
Iceland. Radiocarbon 52:682–696.
Taylor, R.N., M.F. Thirlwall, B.J. Murton, D.R. Hilton,
and M.A.M. Gee. 1998. Isotopic constraints on the
influence of the Icelandic plume. Earth and Planetary
Science Letters 148:E1–E8.
Toolis, R., J. Barrett; N. Boulton; C. Chenery, J. Evans,
D Hall, A. MacSween, M. Melikian, and M. Richards
2008. Excavation of medieval graves at St. Thomas’
Kirk, Hall of Rendall, Orkney. Proceedings of the
Society of Antiquaries Scotland 138:239.
Veizer, J. 1989. Strontium isotopes in seawater through
time. Annual Review of Earth and Planetary Sciences
1:141–167.
Vitòria, L., N. Otero, A. Soler, and À. Canals. 2004.
Fertilizer characterization: Isotopic data (N, S, O,
C, and Sr). Environmental Science and Technology
38:3254–3262.
Journal of the North Atlantic
T.D. Price, K.M. Frei, and E. Nauman
2015 Special Volume 7
136
Vitousek, P.M., M.J. Kennedy, L.A. Derry, and O.A.
Chadwick. 1999. Weathering versus atmospheric
sources of strontium in ecosystems of young volcanic
soils. Oecologia 121:255–259.
Voerkelius, S., G.D. Lorenz, S. Rummel, C.R. Quétel,
G. Heiss, M. Baxter, C. Brach-Papa, P. Deters-Itzelsberger,
S. Hoelzl, J. Hoogewerff, E. Ponzevera, M.
Van Bocxstaele, and H. Ueckermann. 2010. Strontium
isotopic signatures of natural mineral waters, the reference
to a simple geological map and its potential for
authentication of food. Food Chemistry 118:933–940.
Wallace, J.M., R.M. Ellam, I.G. Meighan, P. Lyle, and
N.W. Rogers. 1994. Sr isotope data for the Tertiary
lavas of Northern Ireland: Evidence for open system
petrogenesis, Journal of the Geological Society of
London 151:869–877.
Whipkey, C.E., R.C. Capo, O.A. Chadwick, and B.W.
Stewart. 2000. The importance of sea spray to the
cation budget of a coastal Hawaiian soil: A strontium
isotope approach. Chemical Geology 168:37–48.
Wilson, J.R., S. Pedersen, C.R. Berthelsen, and B.M.
Jacobsen. 1977. New light on the Precambrian Holum
granite, South Norway. Norsk Geolisk Tidsskrift
57:347–360.
Wood, D.A., J.L. Joron, M. Treuil, M.J. Norry, and J. Tarney.
1979a. Elemental and Sr isotope variations in basic
lavas from Iceland and the surrounding ocean floor.
Contributions to Mineralogy Petrology 70:319–339.
Wood, D.A., J. Varet, H. Bougaut, O. Corre, J.-L. Joron,
M. Treuil, H. Bizouard, M.J. Norry, C.J. Hawkesworth,
and J.C. Roddick. 1979b. The petrology, geochemistry,
and mineralogy of North Atlantic basalts:
A discussion based on IPOD Leg 49. Pp. 597–655, In
B.P. Luyendyk, J.R. Cann, et al. (Eds.). Initial Reports.
DSDP 49. US Govt. Printing Office, Washington, DC,
USA.
Woodcock, N.H. 1994. Geology and Environment in Britain
and Ireland. CRC Press, Boca Raton, FL, USA.
Woodcock, N.H. 2000. Geological History of Britain and
Ireland. Blackwell Publishing, Oxford, UK.
Wright, L.E., and H.P. Schwarcz. 1998. Correspondence
between stable carbon, oxygen and nitrogen isotopes
in human tooth enamel and dentine: Infant diets at
Kaminaljuyú. Journal of Archaeological Science
26:1159–1170.