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boulder clay:see driftdrift,
deposit of mixed clay, gravel, sand, and boulders transported and laid down by glaciers. Stratified, or glaciofluvial, drift is carried by waters flowing from the melting ice of a glacier.
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boulder clay[′bōl·dər ‚klā]
till, glacial till, boulder clay
An unstratified glacial deposit which consists of pockets of clay, gravel, sand, silt, and boulders; has not been subject to the sorting action of water; usually has good load-sustaining properties.
an unstratified glacial deposit consisting of fine clay, boulders, and pebbles