From Ohio History Central
Till is a term for an unsorted mixture of clay and rock fragments that was deposited by glacial ice. Till is deposited directly beneath advancing ice or by the melting of stagnant ice. Across large areas of the glaciated two-thirds of Ohio the relatively flat topography is referred to as a till plain and has a thick blanket of till called ground moraine. Hummocky deposits of till formed at the snout of a glacier form end moraine.