The oldest Beverly archaeological tradition is Northern Plano, identified mainly from Agate Basin points. In their Wyoming type site they are 9-10,000 years old; midway in the Prairie provinces, they are 8-9,000 years, and in the Barrenlands only 7-8,000. A thin dispersion of bison hunting camps extends northeast from Wyoming to northern Saskatchewan. At Athabasca and Black Lakes, the prey changed to caribou, with some overlap of both animal ranges in the Beverly forest.
Newly growing lichen, grass and trees gradually followed the glaciers receding northeast of the range. Two arboreal pollen dates near Cree Lake of 8640±240 and 8770±250 years ago (GSC-1446 and 1466; Mott 1971) are not even from the bottom of their cores and indicate earlier deglaciation. Farther north, pollen profiles and a 8000 year old Northern Plano date from KkLn-4 at Grant Lake infer nearby trees (Wright 1976:82-84; Gordon 1976:39-43). Precipitation and runoff were also similar because Plano levels at KkLn-2 and 4 are only a meter above the Dubawnt River. The dates and water level indicate Glacial Lakes Dubawnt and Thelon drained earlier, probably about 9500 years ago, allowing 1000-2000 years for lichen to cover the range sufficiently to provide caribou forage, plus several centuries for humans to adapt to caribou herd following.
If Northern Plano evolved to Shield Archaic, as Wright (1972b:85-86) suggests, Northern Plano sites should be fewer and concentrated, which is the case. Northern Plano alone is on the Taltson River but it and Shield Archaic are on Lake Athabasca and the Thelon River where most (35) sites occur. Despite a poorly surveyed Dubawnt River, the heavy concentration of Grant Lake material suggests the Dubawnt and Thelon Rivers were major Plano caribou migration corridors.
Northern Plano has four radiocarbon dates, the oldest at 7930±500 years (S-834) in KkLn-4 at Grant Lake (Wright 1976, Gordon 1976. A km away at KkLn-2, dates are 7220±850 (S-1056) and 5545±120 years (S-813), the latter on shallow subsurface bone contaminated by humic acid. A date of 6720±140 years (S-2191) in the deepest level of KdLw-1 at Mosquito Lake was associated with only quartzite chips, but is likely Northern Plano.
from Gordon 1996. People of Sunlight; People of Starlight: Barrenland Archaeology in the Northwest Territories of Canada. Archaeological Survey of Canada, Mercury Series Paper 154. Canadian Museum of Civilization, p.219.