THE HYPOTHESIS: In places, the crust of the earth is subject to horizontal forces that cause deformation. These deformational forces may cause the surface of the earth to be locally uplifted, depressed or tilted. Local uplifts may result in hills or mountains. Local depressions may result in lowlands or valleys. Tilting may cause previously flat areas to become inclined. One or more major landforms of the NYC area are due to uplift, depression or tilting caused by deformation.