The recovery of a mysterious wooden pole at the bottom of Lake Huron is fuelling excitement among U.S. and Canadian researchers that they have found more evidence of a "lost world" of North American caribou hunters from nearly 10,000 years ago.
The scientists believe these prehistoric people - who would have been among the earliest inhabitants of the continent - had a "kill site" along a ridge along the present-day U.S.-Canada border that was eventually submerged by rising waters when the glaciers melted at the end of the last Ice Age.
Now drowned under about 35 metres of water in Lake Huron, the Alpena-Amberley Ridge is named for the Michigan and Ontario towns that respectively mark the western and eastern ends of the 160-kilometre-long, 16-km-wide feature.
The theory that the ridge was an ancient hunting ground was first announced in 2009 after the discovery of lake-bottom rock features that appeared to have been arranged by human hands to herd migrating caribou into narrow corridors ideal for spear hunting.
These types of "drive lanes" are still used by some Inuit hunters in Northern Canada to funnel caribou and make hunting them easier.
Other groups of boulders mapped by the Lake Huron researchers are thought to have been "blinds" meant to conceal hunters before they sprang out to attack passing caribou.
The two-metre-long piece of wood, found amid such a rock assemblage during a summer search of Huron's floor for traces of human activity, was later dated to 8,900 years ago, the researchers revealed last month.