The peopling of the Americas has
caused spirited and sometimes heated academic debate among scientists in the
USA for decades.
For centuries the route of entry
has generally been accepted as across the Bering Land Bridge.
The first writer to suggest this
possible route of the entry of people into the American continent was a Jesuit
monk named Jose de Acosta. De Acosta had arrived on the Caribbean coast of
South America at Carthagena and travelled onwards to the settlement of Nombre
de Dios. From here he journeyed through 18 leagues of tropical forest via the
route pioneered by Balboa and De Avila to Panama. Once on the Pacific he took
ship once more and reached Lima in the recently conquered Peru. It was while
travelling to his new posting that he began recording his experiences and
observations of fauna, flora, peoples and geography of the Americas. As an
educated European he had read the extant writings of the ancient philosophers
and upon crossing the equator he later related “He expected, as professed by
the philosophers that he had studied, an unbearable intense heat in crossing
the equator, but found it to be so cool in March, that he laughed at Aristotle
and his philosophy”1
De Acosta spent many years in
Peru carrying out missionary work and lecturing on theology. Initially
assisting the Viceroy, Don Francisco de Toledo he travelled the country for two
years gaining a grounding in geography of the country. Subsequently he lived at
Juli, on the shores of Lake Titicaca the main seat of the Jesuit order in Peru.
His missionary duties required him to travel widely and thus he became
intimately acquainted with the native peoples and their customs.
One theological problem that was
therefore at the forefront of de Acosta's mind was a basic one: scriptures
clearly defined man's origins as being in the Old World, therefore theologians
must account for a branch of humanity in the New World. De Acosta phrases it
thus:
“Scripture
teaches us that all men are descended from a first man. Hence man must have
come to the Indies (The Americas) from
Europe, Asia or Africa, but such pronouncements do not tell us the manner of
travel or the route. ..How could the human race have traversed so great an
immensity of seas and lands? How could so large a number of people have been
concealed for so many centuries?”
De Acosta goes on to logically
rule out intended voyages using navigation techniques as no evidence of such
abilities used by ancient peoples exists in the written or oral traditions of the
three continents known up to the discovery of the Americas. He discounts
accidental voyages as the great diversity of animal life in the New World also
had to arrive there in some manner, and in the case of terrestrial animals this
had to be via a land connection with some continent.
He therefore goes on to conclude
that the Indians and likewise the animals found in the New World probably arrived
via some point in the far north at which the two worlds are either connected or
closely approximate. He speculated that the Old and New Worlds in the far north
either, “continued and joined with the
other” or “they approach on nearer
unto another”1 such that the gap would not greatly hinder migration
of animals or man.
In 1587, after 16 years in the Peru and later, Mexico
de Acosta returned to Spain and occupied various prestigious offices, including
lastly rector of the college at Salamanca. He published three great works based
on the extensive manuscripts he had compiled during his time abroad. These
were: De Natura Novi Orbis, De promulgatione Evangelii apud Barbaros, sive De Procuranda Indorum
salute and above all, the Historia natural y moral de las Indias which contains his theory of the man’s entry
into the New World.
Photo credit: Google Digital Commons
The influence of these works was so profound that de Acosta became known as “the Pliny of the Americas”. Thus the land route for the peopling of the Americas entered the intellectual cannon almost from the beginnings of written history of science.
This close approach of one land mass to the other was first discovered by Semyon Dezhnyov in 1648 but news of the confirmed close proximity of the Asian and American continents only reached Europe 80 years later when Danish-born Russian navigator Vitus Bering entered the strait, now named after him, in 1728.
The theory remained in the realms of theological speculation until late in the 19th century, when Wallace2 suggested that the shallow seas separating Siberia and Alaska, specifically the area around the Bering Strait seemed the most likely site of geologically recent Eurasian-American land connections. In 1898 Wallace3, based on water depth soundings of Bering Sea, Chukchi Sea and Being Strait, wrote that, “in later geologic times, more than once and perhaps during prolonged periods [there existed] a wide terrestrial plain connecting North America and Asia” .
The timing of the Bering Land Bridge formation remained a thorny issue for scientists with best estimates based on the synchronicity of Asian and North American, fossil, mammal faunas as detailed in the works of Osborn4 Willis5 and Simpson6.
The mechanism of Bering Land Bridge formation was initially thought to be related to tectonic events, however in 1934 Daly7 brought forward the theory that sea levels fluctuated drastically during the Ice Ages in response to the amount of water stored on land as continental glaciers such as the Laurentide of North America. Finally the area of the land connection was given its name; Beringia or the Bering Land Bridge by Hulten8 in 1937. His work noted that while large areas of North America and Southern Siberia were glaciated, large areas to the north of these remained ice-free refugia for many boreal plant species and animals and that the two continents were connected by the Bering land Bridge for a considerably length of time.
Thus the timing and existence of the Bering Land Bridge while firmly based in the, then current scientific evidence, required unequivocal data to fully prove the theory. With the intervention of World War Two the uncovering of definitive, confirmatory evidence had to await the emergence of a new generation of scientists working in the region.
One such scientist was David Moody Hopkins. After graduating from the University of New Hampshire in the summer of 1942 with a degree in Geology, he enrolled as a doctoral student at Harvard. Only three weeks into term-time he was offered a job with the U.S. Geological survey in Alaska locating strategic minerals for the war effort. His advisors at Harvard recommended that he take the post and finish his studies later, after al,l at 20 years of age Hopkins was of prime draft age. He thus accepted the job and was at once posted to Alaska. Through the autumn of 1942 and the summer of 1943 Hopkins mapped the distribution of molybdenum and coal deposits but also found time to collect Pleistocene fossils or marvel at, and study the glaciers and mountain scenery around his camps at Muir Inlet and in the Matanuska mountains. Each autumn it was back to Washington D.C. to write up his reports. In late 1944 he chose to write up his reports in Anchorage, Alaska hoping to drafted in Alaska and not back east. Thus it was that he was drafted whilst still in Alaska and did his basic training there. On completion of the course intelligence and aptitude tests were carried on the recruits, by the army to see which assignments they were best suited for. Experience was also a factor. Hopkins thus gave his experience working for the USGS, fictionalised teenage work on the railroad in New Hampshire and lastly experience of meteorological observations based on a class on climatology he had taken at UNH and watching a friend take such measurements. Basically it was an ‘Anything but the Infantry’ strategy. The army took one look at Hopkins’ weatherman experience and posted him 600 miles north to the extremely stormy cold bay, at the base of the Aluetian chain. Here Hopkins spent the rest of the war carrying out meteorological observations and using Hulten’s Flora of the Aluetian Islands to identify and collect plants. He was finally discharged in the spring of 1946 in the wake of the eruption of Okmuk Caldera on Umak Island.
Consequently, he returned safe and sound to Harvard to complete his Ph. D. He studied under Kirk Bryan an early proponent of the multidisciplinary approach to Geology. This approach was certainly absorbed by Hopkins. It was this combined with his experiences in Alaska before and during the war that formed Hopkins approach to Geology, in that he was prepared to take evidence from a wide field of knowledge and synthesise it into new explanations of natural phenomena. It was then that Hopkins began to see himself as more of a paleonaturalist blending the geology of landscape formation and his naturalist interests of early youth. This combination of interests, led him to be one of the first doctoral students to achieve a Ph. D from Harvard in Quarternary Geology.
Going back to work for the USGS Hopkins was able to pursue his interest in the Quartenary Geology of Alaska and in particular the history of the cyclic formation and inundation of the Bering land Bridge. By 1948 he was back in the field, in Alaska with a hand-picked team focussing on the subject that would become his life’s work.
Hopkins at Hammum Creek near the Imuruk River 1948.
Photo Credit O’Neill10
Sigafoos, Quay and Hopkins drying their gear at Lava Lake camp 1948
Photo Credit O’Neill10
Through the late 1940’s and 1950’s Hopkins never missed a season in Alaska, despite the tragically early death of his first wife, a disastrous second marriage and being wed again for a third time! He often based himself around the Seward peninsula and worked with a range of scientist or visited others working in the region such as Louis Giddings and Bob Sigafoos. In 1959, Hopkins‘9 long years of work led him to publish his first major paper on the Bering land bridge. In it he theorised about the first formation of a land bridge in the Miocene, its first inundation at the Miocene-Pliocene boundary and its continued cyclic formation and submergence during the Pleistocene. Casting his mind back to that time Hopkins comments10 that “..it suddenly occurred to me that if we three got together we could perhaps solve the problem of the Bering Land Bridge. We could show whether it existed or not and when it existed or not .. The Land Bridge was in the air. It had been for years.”
Whilst not all of his peers accepted these theories, he was fast becoming the best known and widely published figure in Bering land Bridge research.
Thus it may not seem surprising, that in 1963 he was asked by the International Association for Quarternary Research to organise an all-day symposium on the land bridge for the 1965 INQUA conference.
This galvanised him to begin reaching out to Russian scientists such as Merklin and Petrov and others to request paper proposals for the upcoming symposium. The back and forth of distributing drafts to symposium participants, the insistence that contributors consider and comment on others’ work and address it in print before the symposium, and the judicious editing of the papers ended up with the event being one of the best organised and productive ever organised. It has since been held up as an example of best practice in organising such events. In the year of the symposium it also led Hopkins to jointly publish 1965 published a paper with Merklin and Petrov and other U.S. scientists11.
The work however had only just begun. Now the symposium and it’s papers needed to be organised and published for their full import to be realised. Hopkins set to work with relish. After two years he had edited the monumental tome “The Bering Land Bridge”. It was published in 1967. Hopkins of course, personally wrote the summary chapter12.
Photo credit: Google Digital Commons
The influence of these works was so profound that de Acosta became known as “the Pliny of the Americas”. Thus the land route for the peopling of the Americas entered the intellectual cannon almost from the beginnings of written history of science.
This close approach of one land mass to the other was first discovered by Semyon Dezhnyov in 1648 but news of the confirmed close proximity of the Asian and American continents only reached Europe 80 years later when Danish-born Russian navigator Vitus Bering entered the strait, now named after him, in 1728.
The theory remained in the realms of theological speculation until late in the 19th century, when Wallace2 suggested that the shallow seas separating Siberia and Alaska, specifically the area around the Bering Strait seemed the most likely site of geologically recent Eurasian-American land connections. In 1898 Wallace3, based on water depth soundings of Bering Sea, Chukchi Sea and Being Strait, wrote that, “in later geologic times, more than once and perhaps during prolonged periods [there existed] a wide terrestrial plain connecting North America and Asia” .
The timing of the Bering Land Bridge formation remained a thorny issue for scientists with best estimates based on the synchronicity of Asian and North American, fossil, mammal faunas as detailed in the works of Osborn4 Willis5 and Simpson6.
The mechanism of Bering Land Bridge formation was initially thought to be related to tectonic events, however in 1934 Daly7 brought forward the theory that sea levels fluctuated drastically during the Ice Ages in response to the amount of water stored on land as continental glaciers such as the Laurentide of North America. Finally the area of the land connection was given its name; Beringia or the Bering Land Bridge by Hulten8 in 1937. His work noted that while large areas of North America and Southern Siberia were glaciated, large areas to the north of these remained ice-free refugia for many boreal plant species and animals and that the two continents were connected by the Bering land Bridge for a considerably length of time.
Thus the timing and existence of the Bering Land Bridge while firmly based in the, then current scientific evidence, required unequivocal data to fully prove the theory. With the intervention of World War Two the uncovering of definitive, confirmatory evidence had to await the emergence of a new generation of scientists working in the region.
One such scientist was David Moody Hopkins. After graduating from the University of New Hampshire in the summer of 1942 with a degree in Geology, he enrolled as a doctoral student at Harvard. Only three weeks into term-time he was offered a job with the U.S. Geological survey in Alaska locating strategic minerals for the war effort. His advisors at Harvard recommended that he take the post and finish his studies later, after al,l at 20 years of age Hopkins was of prime draft age. He thus accepted the job and was at once posted to Alaska. Through the autumn of 1942 and the summer of 1943 Hopkins mapped the distribution of molybdenum and coal deposits but also found time to collect Pleistocene fossils or marvel at, and study the glaciers and mountain scenery around his camps at Muir Inlet and in the Matanuska mountains. Each autumn it was back to Washington D.C. to write up his reports. In late 1944 he chose to write up his reports in Anchorage, Alaska hoping to drafted in Alaska and not back east. Thus it was that he was drafted whilst still in Alaska and did his basic training there. On completion of the course intelligence and aptitude tests were carried on the recruits, by the army to see which assignments they were best suited for. Experience was also a factor. Hopkins thus gave his experience working for the USGS, fictionalised teenage work on the railroad in New Hampshire and lastly experience of meteorological observations based on a class on climatology he had taken at UNH and watching a friend take such measurements. Basically it was an ‘Anything but the Infantry’ strategy. The army took one look at Hopkins’ weatherman experience and posted him 600 miles north to the extremely stormy cold bay, at the base of the Aluetian chain. Here Hopkins spent the rest of the war carrying out meteorological observations and using Hulten’s Flora of the Aluetian Islands to identify and collect plants. He was finally discharged in the spring of 1946 in the wake of the eruption of Okmuk Caldera on Umak Island.
Consequently, he returned safe and sound to Harvard to complete his Ph. D. He studied under Kirk Bryan an early proponent of the multidisciplinary approach to Geology. This approach was certainly absorbed by Hopkins. It was this combined with his experiences in Alaska before and during the war that formed Hopkins approach to Geology, in that he was prepared to take evidence from a wide field of knowledge and synthesise it into new explanations of natural phenomena. It was then that Hopkins began to see himself as more of a paleonaturalist blending the geology of landscape formation and his naturalist interests of early youth. This combination of interests, led him to be one of the first doctoral students to achieve a Ph. D from Harvard in Quarternary Geology.
Going back to work for the USGS Hopkins was able to pursue his interest in the Quartenary Geology of Alaska and in particular the history of the cyclic formation and inundation of the Bering land Bridge. By 1948 he was back in the field, in Alaska with a hand-picked team focussing on the subject that would become his life’s work.
Hopkins at Hammum Creek near the Imuruk River 1948.
Photo Credit O’Neill10
Sigafoos, Quay and Hopkins drying their gear at Lava Lake camp 1948
Photo Credit O’Neill10
Through the late 1940’s and 1950’s Hopkins never missed a season in Alaska, despite the tragically early death of his first wife, a disastrous second marriage and being wed again for a third time! He often based himself around the Seward peninsula and worked with a range of scientist or visited others working in the region such as Louis Giddings and Bob Sigafoos. In 1959, Hopkins‘9 long years of work led him to publish his first major paper on the Bering land bridge. In it he theorised about the first formation of a land bridge in the Miocene, its first inundation at the Miocene-Pliocene boundary and its continued cyclic formation and submergence during the Pleistocene. Casting his mind back to that time Hopkins comments10 that “..it suddenly occurred to me that if we three got together we could perhaps solve the problem of the Bering Land Bridge. We could show whether it existed or not and when it existed or not .. The Land Bridge was in the air. It had been for years.”
Whilst not all of his peers accepted these theories, he was fast becoming the best known and widely published figure in Bering land Bridge research.
Thus it may not seem surprising, that in 1963 he was asked by the International Association for Quarternary Research to organise an all-day symposium on the land bridge for the 1965 INQUA conference.
This galvanised him to begin reaching out to Russian scientists such as Merklin and Petrov and others to request paper proposals for the upcoming symposium. The back and forth of distributing drafts to symposium participants, the insistence that contributors consider and comment on others’ work and address it in print before the symposium, and the judicious editing of the papers ended up with the event being one of the best organised and productive ever organised. It has since been held up as an example of best practice in organising such events. In the year of the symposium it also led Hopkins to jointly publish 1965 published a paper with Merklin and Petrov and other U.S. scientists11.
The work however had only just begun. Now the symposium and it’s papers needed to be organised and published for their full import to be realised. Hopkins set to work with relish. After two years he had edited the monumental tome “The Bering Land Bridge”. It was published in 1967. Hopkins of course, personally wrote the summary chapter12.
Hopkins on publication day.
Photo Credit O’Neill10
Cover of the ‘Bible’ as
colleagues began to call the Bering Land Bridge.
Photo credit N Barden
The results presented from many
different disciplines and by scientist worldwide and their subsequent analysis
and synthesis by Hopkins represented a huge step forward in the understanding
of the Bering Land Bridge. In summary the results were:
·
During the Pleistocene Era (2 million years ago
to 10 000 years ago), Beringia was a large, ice-free land mass during periods
of glaciation
·
As the climate warmed and the glaciers melted, the
Bering-Chukchi platform would flood, severing the terrestrial connection
between North America and Asia. Eventually, the climate cooled and glaciers
reformed, exposing the Bering Land Bridge again.
·
When exposed, this land bridge was covered with
vegetation and supported a variety of animal life
·
That 4 waves of mammalian immigration had
occurred over the land bridge, once during early Miocene, again at the
Pliocene-Pleistocene boundary and probably at least twice more during
Pleistocene. Furthermore the climate on the land bridge appeared to be
temperate, humid and forested in the first two episodes, temperate grasslands
in the mid Pleistocene and only in late Pleistocene was the climate
significantly colder being represented by tundra, steppe and Taiga plant
communities. Additionally there was some back migration from the Americas to
Asia.
·
That the land bridge had existed at least nine times during the Pleistocene
Table by Reppening showing
envisaged mammalian migrations during the late Pliocene and Pleistocene13
Whilst a huge amount of the work
was accepted by the scientific community at large many questions remained for
Hopkins. For example was it possible to reconstruct the ancient climate on and
near the land bridge and more particularly could he reconstruct the climate
during the LAST land bridge. For this it was assumed would allow basic questions
about the peopling of the Americas to be, at last, definitively answered.
During the editing of The Bering
land Bridge in 1966, Hopkins did not forsake his usual Alaskan, summer field
season. Whilst camped on the north shore of the Seward peninsula, Dale Guthrie
and John Matthews turned up to study fossil insects in sedimentary deposits
that Hopkins had previously recommended to them at the adjacent, Cape Deceit on
Kotzebue Sound. As Hopkins says10: “I had reason to think that Cape deceit had a record that went at least
back through the last glaciation, the IIlinoian. I had no idea that it would go
back, possibly, to the Pliocene.. They started digging at Cape Deceit, which
turned out to be one of the most important contributions ever to Beringian Paleoecology.”
The Pliocene/Pleistocene boundary fossil faunal were presented in The Bering
land Bridge, a year later by Reppening13. It was not these fossils,
impressive as they were, however, that were of key importance. It was the
fossil pollen, plant fragments and body parts of assorted insects that were the
real goldmine. For it was in these, that scientist could start to reconstruct
the paleoclimate of the Bering Land Bridge. Their work indicated that the early
Pleistocene climate in the region had been a dry, scantily clad Tundra which
became grassland dominated in mid-Pleistocene and Steppe Tundra at the end of
the geologic period and that in warmer interglacials treelines had been
considerably further west, and in fact as far west as Cape Deceit, on at least
two occasions. In other words there were considerable periods, during which,
the migration of large herbivores such as mammoths and presumably their human
hunters could have crossed the land bridge throughout the Pleistocene.
This view of the paleoecology of
Beringia was not shared by all, however. Another of Hopkins’ associates Paul
Colinvaux, had, at Hopkins’ suggestion had carried out sediment coring at
Imuruk Lake. The view of the paleoecology of Beringia he drew from the fossil
pollen record was in stark contrast to that of Guthrie and Matthews. He viewed
Beringia as an , a windy, forsaken
landscape of sparse tundra, “a dusty plain stretching to the horizon, vegetated
between the bare patches with a low mat of sedges and grasses looking like a drier
version of the modern arctic plain.”14
Twelve years after the
publication of his first book Hopkins arranged a second conference to discuss
the current work of the Paleoecology of Beringia, the Wenner-Gren Foundation
for Anthropological Research Symposium was held June 8-17, 1979 in Burg
Wartenstein Austria. The resulting book15, The Paleoecology of
Beringia was published in 1982.
The publication, caused, what has
become the longest running argument in Beringian studies. Ritchie and Cwynar
stated, in 198218 that “We
suggest that the ‘Arctic Steppe Biome’ never existed”. Also critical of the
productive Mammoth Steppe theory was Collinvaux and West’s 198414 view
of the Beringian Paleoecology. This was swiftly followed in 198516 by
Guthrie with his provocatively titled “Woolly Arguments Against the Mammoth
Steppe”. Colinvaux’s 1986 reply17 was equally biting. The situation
became so bad that Guthrie is reputed to have dumped a huge, muddy, freshly dug
mammoth tusk on Colinvaux’s desk and heatedly told him that he had dated
Mammoth remains spanning the whole of the existence of the Bering land Bridge.
Colinvaux was unimpressed and continued to insist (in print) that these
skeletal remains were the result of migrations of mammoth from distant productive areas. Guthrie’s response “They have to eat
every 12 hours!” and evidence in the form of the grass and herbaceous gut
contents of mammoth remains sealed in permafrost from Siberia fell on deaf
ears.
What was needed was more evidence
to demonstrate one way or another whether Beringia was a cold, unproductive
arctic desert, or a rich Mammoth Steppe with herbaceous vegetation capable of
supporting large herds of grazing animals. Unsurprisingly some of the evidence
was actually and literally uncovered by Hopkins himself. In 1988, following up
on a 1974 observation of what he believed to be a preserved Pleistocene ground
surface, he took his graduate students Claudia Hofle and Victoria Goetcheus to
the Devil Mountain-Cape Espenberg area. Here, sealed by a layer of volcanic
tephra, they uncovered actual preserved remains of a rich array of herbaceous
plants, shrubs and grasses. Furthermore, radiocarbon dating of the remains gave
a date of 18000BP, i.e. in the middle of the period disputed by the
Palynologists, Colinvaux and Ritchie on one hand and Guthrie and Young on the
other. This supported the Mammoth Steppe theory. Later publications by Hofle23a
and b and Goetcheus24a and b confirmed this.
Further evidence came to light
from Cinq-Mars’ excavation of the Blue Fish Caves19 in the Yukon.
Cinq-Mars states:
“More importantly, these results demonstrate that the mammoth steppe..
constituted an essential element of the Glacial Maximum biotope of eastern
Beringia (between about 17,000 and 25,000 BP).”
Basically Cinq-Mars is saying that
their palynological and other data show that Mammoth Steppe did exist at the
time of the sediment formation over height of the last glacial maxima (ca.
22000BP). In other words their data refute the “productivity paradox” of Schweger
et al.20 (1982) and the position of Cwynar and Ritchie (1980)21
and support the position of Guthrie (1985)16 and Matthews
(1982)22 that the environment was extremely rich and capable of
supporting an extensive megafaunal assemblage.
Further publications, including
Guthrie 200125 have thus stabilised the view that the Mammoth Steppe
had actually existed as suggested and was capable supporting large Pleistocene
grazing fauna which, in turn, were followed into the new world by humanity.
Here Hopkins’ direct involvement
of the investigations of the Bering Land Bridge ends. He died aged 79, in
November 2001.
Research has of course,
continued. In fact Hopkins’ hypothesis in 1967 that the Bering Land Bridge had
existed at least nine times has been updated by workers such as Pielou (1991)
who theorises26 that the Bering Land bridge has existed at least 20
times during the Pleistocene.
The Bering land Bridge at the
height of the Illinoian glaciation. From Hopkins12 p462
The Bering land Bridge at the
height of the Wisconsin glaciation. From Hopkins12 p462
References
1. Joseph de Acosta, Edward
Grimston, Clements Robert Markham, The Natural and Moral Historie of the
Indies, Hakluyt Society, 1880 pp.i-ii
2. Wallace, H. R. 1876. The
geographical distribution of animals: harper, New York 2 vols.
3. Dawson, G. M. (1898). Geologic
notes on some of the coasts and islands of Bering Sea and vicinity: Geol. Soc.
American Bulletin., v.5 p117-146
4. Osborn, H. F. 1909. Cenozoic
mammal horizons of western North America: US Geol. Survey Bull. 361 138p.
5. Willis, Bailey. 1909.
Paleogeographic maps of North America: 13, Eocene-Oligocene North America:
Jour. Geology v.17 p506-508; Quarternary North amerioca: Jour. Geology v17
p600-602
6. Simpson, G. G. 1947. Holarctic
mammalian faunas and continental relationships during the Cenezoic: Geol. Soc.
America Bull., v.58 p.613-687
7. Daly, R.A. 1934. The changing
world of the Ice Age: Yale Univ. Press, 271p.
8. Hulten, Eric. 1937. Outline of
the history of arctic and boreal biota during the Quarternary Period:
Bokforlags Aktiebolaet Thule, Stockholm, 168 p.
9. Hopkins, D.M. 1959. Cenozoic
history of the Bering Land Bridge. Science, 129, 1519–1528.
10. O’Neill, D. 2004. In The Last
Giant of Beringia. Westview Press Boulder Colorado p. 107
11. Hopkins, D.M., MacNeil, F.S.,
Merklin, R.L. and Petrov OM (1965) Quaternary correlations across Bering
Strait. Science, 147, 1107–1114.
12. Hopkins, D.M. 1967. The
Cenozoic history of Beringia—A Synthesis., in The Bering Land Bridge Hopkins,
D.M, ed. Stanford University Press.
13. Reppening, C. 1967 Palearctic-Nearctic Mamalian Dispersal in
the Late Cenozoic. In The Bering
Land Bridge Hopkins, D.M, ed. Stanford University Press.
14. Colinvaux, Paul A. and
Frederick H. West. 1984. The Beringian
Ecosystem. The Quarterly Review of Archaeology, Sept issue 1984.
15. Hopkins, D.M., Matthews,
J.V., Schweger, C.E. and S.B. Matthews. 1982. The Paleoecology of Beringia.
Wenner-Gren Foundation for Anthropological Research. Symposium. New York :
Academic Press.
16. Guthrie, R. Dale. 1985. Woolly
Arguments Against the Mammoth Steppe - A new look at the Palynological Data.
The Quarterly Review of Archaeology, Sept 1984.
17. Colinvaux, Paul, A. 1986.
Plain Thinking on Bering land Bridge Vegetation and Mammoth Populations. The
Quarterly Review of Archaeology, March 1986.
18. Ritchie, J.C. and L. Cwynar.
1982. “The Late Quaternary Vegetation of the North Yukon.” In: Paleoecology of
Beringia, ed. D.M. Hopkins et al. (New York, Academic Press) pp. 113-126.
19. Cinq-Mars, Jacques and
Richard E. Morlan. 1999. “Bluefish Caves and Old Crow Basin: A New Rapport,” in
Ice Age Peoples of North America, ed. by Robson Bonnichsen and Karen L.
Turnmire, pp. 200-212. Corvallis: Oregon State University Press for the Center
for the Study of the First Americans.
20. Schweger, C.E., J.V. Mathews,
Jr., D.M. Hopkins and S.B. Young (eds.) 1982.
“Paleoecology of Beringia – A
Synthesis.” In: Paleoecology of Beringia, ed. D.M. Hopkins et al. (New York,
Academic Press) pp. 425-444.
21. Cwynar, L. and J.C.
Ritchie.1980. Arctic steppe-tundra: A Yukon perspective. Science Vol. 208, pp.
1375-1377.
22. Matthews, J.V., Jr. 1982.
East Beringia during Late Wisconsin Time: A Review of the Biotic Evidence. In:
Paleoecology of Beringia, ed. D.M. Hopkins et al. (New York, Academic Press)
pp. 127-150.
23a. Hoefle, C. L. Buried Soils
on Seward Peninsula, Northwest of the Bering Land Bridge. Masters thesis,
University of Alaska Fairbanks, August 1995.
23b. C. Hoefle, C. L. Ping, D.
Mann and M. Edwards
Buried Soils on Seward Peninsula:
A Window into the Paleoenvironment of the Bering Land Bridge. Current Research
in the Pleistocene Vol. 11, 1994.
24a. Goetcheus, Victoria G. 1995.
The vegetation of A 17 Buried Surface on the Northern Seward Peninsula. 24th
Artic Workshop, Quebec. Abstracts, 1995.
24b. V. G. Goetcheus, D. M.
Hopkins, M. E. Edwards and D. H. Mann
Window on the Bering Land Bridge:
A 17,000-year-old Paleosurface on the Seward Peninsula, Alaska Current
Research in the Pleistocene Vol. 11, 1994
25. Guthrie, Dale. R. 2001. Origin
and causes of the mammoth steppe: a story of cloud cover, woolly mammal tooth
pits, buckles, and inside-out Beringia
Quaternary Science Reviews 20
ps.549-574
26. Pielou, E.C. 1991. After the Ice Age: The Return of Life to
Glaciated North America. University of Chicago Press, Chicago
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