Atlas Obscura
June 8, 2017
DURING THE LAST GLACIAL PERIOD, when much of North America was covered in vast, thick sheets of ice, most of the continent’s trees were relegated to warmer latitudes in Mexico and along the Gulf Coast. When the glaciers slowly began to retreat about 18,000 years ago, the land opened up to occupation—from humans, who migrated in from the north, and the trees, which followed more temperate climes from the south.
