An unsorted sediment deposited directly by a glacier and not reworked by meltwater. A till is a stiff unstratfied 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.
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