Ancient Pacific Coast Migration Route
[All dates calibrated by calpal 2007]

The emergent territories of Beringa provided a land bridge between NE Siberia and North America
from ca 40000-9000BCE.Except for a relatively narrow channel proximal tp the Siberian coastline,
which provided a conduit to an inland sea,the Aleutian Islands were the approximate southern
extent of Beringia during the last glacial maximum [LGM].
The Yana River flows 880km northward through NE Siberia to the Laptev Sea at 72 degrees N.
The Yana site,which is on the banks of the river at about 71 degrees N,was occupied 30090BCE
+/-210a.The lithic inventory consists of unifacial and bifacial flaking of local siliceous,slate peb-
bles and quartz crystal core tools and flakes,which are the by-products of implement manufacture.
A number of flakes were worked unifacially and may have ventral retouch.The major tool types
are cores,choppers,chopping implements,bifacial and unifacial tools,which include numerous
pointed pieces,side and angle scrapers,chisel type items,retouched flakes and a hammer stone.
The Yana stone assemblage is different from the later industries at the Dyuktai cultural sites in
NE Siberia.There are no pristmatic blades or wedge shaped cores at Yana [M Dashtzeran,1993;
V Pitulka,2004].The presence of hunter-gatherers at this river game crossing predates the
modification of fauna bones in the Canadian Yukon by ca 1Ka [J Cinq Mars,2002].
Coastal migrations from NE Siberia to North America could have occurred any time after 30000
BCE,when there was adequate sustenance for humans and appropriate refugia for seaboard voy-
agers.During the LGM,temperaturesalong the Pacific coastline of Oregan were about 5 degrees C
colder than today and the average rainfall was higher than it is now.There was a steep gradient
between the littoral zone and the arid interior.Marine cores about 120km offshore from Oregan
indicate that the predominant winds were from the east,where there was a high pressure cell over
the inland ice sheets.The east winds minimized offshore upwelling,which contributes to marine
biological diversity,Core segments,that date to the Bolling-Allerod warm era,contain Redwood
pollen.Redwood growth is dependent on coastal fog,which is initiated by offshore upwelling.The
cool,dry climatic conditions of the 10800-9650BCE era depressed upwelling and the average rise
in sealevel fell from 40-3mm,[R Hall,2004].
T Keifer [2005] and M Sarthien [2006] have attempted to reconstruct the climatic conditions along
the Pacific seaboard post 17000BCE +/-1Ka.These preliminary endeavours are based on a low
number of control points.Reconstruction of prehistoric sealevel temperatures can be tenuous.
They have tentatively identified a number of warmer periods,when marine foragers and hunters
could have travelled to North America.Keifer contends that the Pacific regions were characterized
by variable rates of deglacial warming.He estimates that about half of this occurred prior to ca
12650BCE.A temperature rise in the Pacific region,that commenced ca 13425-12950BCE seems
to predate the onset of the North Atlantic warm Bolling era.[There may have been an Antarctic
influence on portions of the Pacific coastal climate??].There is localized variablity in the Pacific
region.South China Sea records show an abrupt temperature increase ca 12650BCE,which could
imply that the margin seas were influenced more by continental atmospheric variability than open
sea locations,[ibid].Sarthien proposed,that a severe climate deterioration in east Asia,broadly
coincided withthe cold European Heinrich event 1,when weather conditions fluctuated.He sug-
gested that people moved to the coast during this period.
Keifer identified warming eras from 16500-14500BCE and post 13200BCE in the northern Pacific
region.Sarthien contends that there were discernible temperature rises in the NW Pacific area
from 16200-15200,14900-14300 and 14150-12650BCE.Collation of the above implies that the
weather was favourable for people movements along the Pacific seaboard from ca 16200-15200,
14800-14500 and 13200--12650BCE.[There may have been an earlier window of opportunity
during the LGM].
The LGM Cordilleran ice sheets covered most of British Columbia and a segment of Alaska.G
Mandryk [2001] proposed that the north Pacific and Gulf of Alaska "might" have been largely ice
free during the LGM.Initial deglaciation along the seaboard may have commenced at some
locales ca 17000-16000BCE.D Mann reported large ice free areas on Kodiak Island and at least
one on the Alaska Peninsula ca 18000-15000BCE.There is palaeocogical evidence of treeless,
herb anddwarf shrub tundra on Washington State's Olympic Peninsula from ca 16370-14020BCE.
Sedge grasses,herbs and dwarf shrubs were recorded in NE Haidi Gwaii from 17000-13500 BCE.
A twig in ponded sediment on Graham Island dates to 16090 +/- 700a.Terrestial vegetation was
established on Graham Island,haidi Gwaii,ca 17000BCE,when the western shores of Haidi Gwaii
became habitable.A partial bear femur on Moseby Island dates to 15940BCE +/-70a,which
suggests that humans might have been able to survive on the island for a short time,[D Fedject-
al,2005].
Studies [ie;beetles,etc] infer that climatic conditions along the southern most shoreline of Beringia
were not generally harsh during some phases of the LGM.Elias [1997] contends that lowland por-
tions of southern Beringia were covered in Mesic birch and grominoid during the LGM.Dry gromin-
oid tundra vegetation grew on the Seward Peninsula uplands,[Goetehaus,2001]Brown bears
recolonized Beringia ca 22450BCE [P Matheus,2004],which lends credence to the premise that
the southern,shoreline lowlands had sufficient marine and terrestial resources to sustain nomadic
humans during the LGM.
It is possible to drift from Japan to Alaska-British Columbia on the Kuro Siwo current in 3-4
monthsNumerous Japanese fishermen have survived the voyage,[Hornell,1945],which would
been shorter,when sealevel was lower.The optimum routes for coastal migrations from NE
Siberia to South America from ca 30000-12000BCE now lie beneath the waters of the Pacific
Ocean.The discovery of any evidence of ephemeral sites along the shoreline during this era
would be extremely fortuitous.The above suggests that there were numerous windows of
opportunity for people to migrate to the Americas post 30000BCE.The most favourable were
before and after the LGM,when the seas provided greater bounty.