Once Upon a Time: When Lake Huron split in two

One day, ten thousand years ago, hunters crouched behind boulders in the middle of Lake Huron, as a long line of caribou approached on their spring migration across the lake … the hunters’ winter famine would soon be over.

How was it possible to hunt caribou in mid-lake? University of Michigan archaeologist Dr. John O’Shea revealed the answer at a talk on August 25, 2023 in Point Clark (ON).

For a few thousand years, the lake level was unusually low, so low that a narrow bridge of land appeared, splitting Lake Huron in two. Called the Alpena-Amberley Ridge, it connected North Point (near Alpena MI) to Point Clark (near Amberley ON).

This meant that you could walk across the middle of Lake Huron on a natural causeway 160 km long and just a few kilometres across—wide enough for caribou to cross on their spring and fall migrations, and for hunters to lay in wait for them.

Before a packed hall of 200 in Point Clark Community Centre, Dr. O’Shea showed his proof—photographs taken on dives to the ridge, now under 40 metres of water. Divers found evidence left behind by caribou hunters: hunting blinds and drive lanes constructed with boulders to funnel the animals for easier harvest. Recent dives have revealed a cervid tooth fragment, stone micro-blades, house rings and a central fireplace.


With the help of submersible vehicles, the Alpena-Amberley Ridge has steadily yielded its secrets to Dr. O’Shea and his dive team. They have found features on the ridge between 8,000 and 9,800 years old. A peat deposit, for example, dated to around 9,500 years ago.

In 2022, they retrieved samples from a bed of peat and a rooted cedar stump on the ridge. Radiocarbon dating put them at about 9,000 years old. Remarkably, the samples came from a location predicted by a class of Alpena High School students. They used a virtual world model to predict likely spots where caribou would be found, in this case, beside a river connecting two lakes. Ancient DNA from the peat is now under analysis to reveal what animals were there.

Dr. O’Shea concluded with a plea … since he could explore only down to the Canadian border in mid-lake, he urged Canadian researchers to investigate the promising south half of the ridge.


by Robin Hilborn
for the Bruce County Historical Society