The Probert Encyclopaedia of Rocks & Minerals

TILL

In geology, a till is a stiff unstratified deposit of clay mixed with sand, gravel and boulders without lamination, formed in a glacier valley by means of the waters derived from the melting glaciers. The term is sometimes applied to alluvium of an upper river terrace, when not laminated, and appearing as if formed in the same manner.
Research Till