Vegetation zones during and after the Last Glacial Maximum
Peter Alaca
discussion about the peopling of America.
Ray, N. and J. M. Adams (2001).
"A GIS-based Vegetation Map of the World at the
Last Glacial Maximum (25,000-15,000 BP)"
Internet Archaeology 11
Abstract
"A preliminary, broad-scale vegetation map
reconstruction for use by archaeologists and
anthropologists is presented here for the
world at the Last Glacial Maximum (18,000 BP,
but broadly representing the interval from
25,000 to 15,000 BP). The global LGM map was
produced from a range of literature and map
sources, and drawn on a GIS with topographic
information. Extended coastlines due to LGM
sea-level drop were obtained using
bathymetric information."
The original is only accessible by subscribers
<http://intarch.ac.uk/journal/issue11/rayadams_toc.html>
but here is a minimal version with the maps
<http://www.ncdc.noaa.gov/paleo/pubs/ray2001/>
and the full 44 pp article is avialable for free
from there
<http://www.ncdc.noaa.gov/paleo/pubs/ray2001/ray_adams_2001.pdf>
[1.9 mb]
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Jonathan Adams
"Global land environments since the last interglacial"
<http://www.esd.ornl.gov/projects/qen/nerc.html>
North America during the last 150,000 years
<http://www.esd.ornl.gov/projects/qen/nercNORTHAMERICA.html>
(or click 'North America'on the main page)
qoutes concerning the key period
"14,000 radiocarbon years ago.
Indicators of a significant warming and
moistening of climate begin to appear at
around this time, but only in some areas.
In Alaska, a widespread change from herb-
dominated to moist shrub-dominated tundra
occurred at around this time, suggesting
moister and slightly warmer conditions
(Andrews & Brubaker 1993.). A similar trend
towards moister and warmer conditions is seen
in the changing tundra flora and insect fauna
on the eastern part of the Beringian land
bridge (Elias et al. 1996).
Further retreat of the Laurentide ice sheet
had occurred, but the future ice-free
corridor still remained blocked by around 800
km of ice."
"13,000 radiocarbon years ago.
The vegetation distribution seems to have
been much the same as at 14,000 14C years
ago, though with continuing glacial retreat
exposing new surfaces in North America. At
around this time, a continuous ice-free
corridor opened for the first time beween
Alaska and the contiguous USA.
However, for a considerable part of its
length (about 750 km) it would have been less
than 50 km wide, and further obstructed in
several places by large meltwater lakes.
The chronology of the first appearance of the
ice free corridor is not completely settled
however; although the southern and northern
ends were open by this time, it is quite
possible that the central region was still
closed.
However, conditions at the southern end of
the ice-free corridor (e.g. in the area
around 50-52 deg.N and 110-115 deg.W) still
seem to have been fairly arid. Burns et al
(1993) note the absence of radiocarbon dates
on faunal remains between about 21,300 and
11,600 14C y.a. in the Edmonton area,
suggesting that the landscape was incapable
of supporting fauna during this interval.
Beaudoin suggests - on the basis of various
pollen sites - that the vegetation in
southern Alberta between about 16,100 to
11,900 14C y.a. was a dry Artemisia-Betula
shrubland."
--
p.a.
Peter Alaca
> Some sources which can be of help in the current
> discussion about the peopling of America.
>
> Ray, N. and J. M. Adams (2001).
> "A GIS-based Vegetation Map of the World at the
> Last Glacial Maximum (25,000-15,000 BP)"
>
> Jonathan Adams
> "Global land environments since the last interglacial"
In addition is here a lot of information
about Alaska en Beringia
Thomas Ager et al
"Ecosystem and Climate History of Alaska"
http://esp.cr.usgs.gov/research/alaska/index.html
--
p.a.