All of Michigan was completely covered with ice 20,000 years ago, and the glacial ice in this region was as much as one mile thick. As its enormous weight scraped across the ground, the glacier collected boulders, stone, gravel, silt, and sand. Eventually the glacial ice began to melt, sometimes unevenly, creating lobes or fingers of outstretching ice. Park Lyndon lay in a valley between two lobes and is part of an interlobate region that runs diagonally from Lake Orion in Oakland County to the Irish Hills area of Jackson County. As more melting occurred, giant blocks of ice fell from the glacial lobes into the valley between them, some one-quarter mile in size. Boulders, course sand, and gravel were deposited on and between the blocks. When the ice melted, a knob and kettle landscape formed, with knobs, or high areas, made of glacial deposits and kettles, or low areas, marking where the blocks once stood. This knob and kettle terrain is not found in the eastern parts of Washtenaw County. The ridge here is an esker, formed when a meandering stream of meltwater carrying sand, gravel, and stones of various sizes flowed under, within, or on top of the glacier, and when the ice melted these deposits became a ridge winding like a river channel.