rock flour


noun

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Origin of rock flour

First recorded in 1880–85
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Example sentences from the Web for rock flour

  • Mountains were moved piecemeal, and ground to boulders, pebbles, and rock-flour in the moving.

  • Nearly all of the soil in the Park is rock-flour that was ground by glaciers, and in part distributed by them.

    Your National Parks|Enos A. Mills
  • Mountains are moved piecemeal, and are ground to boulders, pebbles, and rock-flour in the moving.

    Your National Parks|Enos A. Mills

British Dictionary definitions for rock flour

rock flour

noun

very finely powdered rock, produced when rocks are ground together (as along the faces of a moving fault or during the motion of glaciers) and are thus chemically unweathered
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012