Geology
Underlying the Albany Pine Bush is a bedrock consisting of shale and siltstone, laid down 450 million years ago during the Middle Ordovician. The bedrock is covered by glaciolacustrine deposits which make up the sandy topsoils of the barrens.
As the glaciers of the Wisconsin glaciation began to recede from the Hudson Valley area, a glacial lake known today as Lake Albany extended across the mid and upper Hudson Valley and a large delta formed west of Albany where the predecessor of the Mohawk River flowed into the lake. Along the shoreline of the lake, lacustrine sands were deposited between the present-day cities of Hudson and Glens Falls; this became the Hudson Valley sandplain. Relieved from the weight of the glacier, the land began to rebound, and the lake receded by draining into the Hudson River, the deposits of sand in the delta area were then sculpted by wind into sand dunes. Plants later colonized the land and stabilized the dunes. The Pine Bush originally occupied 40 square miles (100 km2), at which point it was the largest inland pine barrens in North America.
Read more about this topic: Albany Pine Bush