At the foot of Stissing Mountain lies the ancient Thompson Pond Basin, which formed nearly 15,000 years ago when a melting ice chunk created a depression or kettle. Over time, the kettle divided into three interconnected water bodies, including Thompson Pond, which forms the headwaters of a major tributary of the Hudson River. The basin's pond, cattail marsh, swamp and upland forest support a wondrously diverse array of wildlife.