boulder clay

American  

noun

Geology.

1. a glacial deposit consisting chiefly of unstratified clay with embedded boulders.

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boulder clay British  

noun

1. an unstratified glacial deposit consisting of fine clay, boulders, and pebbles See also till 4

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Etymology

Origin of boulder clay

First recorded in 1855–60

Example Sentences

Happisburgh, home to about 1,100 people, is so susceptible to erosion because the cliffs are made from boulder clay which slumps when wet.

From BBC

Great deposits of till and boulder clay that lay beneath the glaciers were abandoned in situ, and remain as an unsorted mixture of large boulders, pebbles and mingled fragments, embedded in clay or sand.

From Project Gutenberg

Glacial boulder clay lies over much of the lower ground, and ridges of gravel and sand flank the hills and form extensive sheets.

From Project Gutenberg

Most of the county is covered by a superficial deposit of glacial drifts, sands, gravel and in places boulder clay, as at Epping, Dunmow and Hornchurch where the drift lies beneath the Thames gravel.

From Project Gutenberg

The largest transported mass occurs at Linksfield, where a succession of limestones and shales rests on boulder clay and is covered by it, which from the fossils may be of Rhaetic or Lower Lias age.

From Project Gutenberg