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 • Dec. 30, 2022

They consist of pieces of chalk, similar to those which drop annually in thousands upon thousands down the cliffs from the boulder clay between Bridlington and Flamborough.

From Ancient Egyptian and Greek Looms by Roth, H. Ling (Henry Ling)

The Dombes is characterized by an impervious surface consisting of boulder clay and other relics of glacial action.

From Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 6 "Dodwell" to "Drama" by Various

And this must have taken place before the glacial period, because the glacial boulder clay lies upon the Kimeridge clay, which normally underlies the chalk. 

From Records of Woodhall Spa and Neighbourhood Historical, Anecdotal, Physiographical, and Archaeological, with Other Matter by Walter, James Conway

At first, when traces of a temperate flora and fauna were discovered intercalated between two layers of boulder clay, their presence was explained by the supposition of a mild inter-glacial period.

From The History of the European Fauna by Scharff, Robert Francis