Origin of rock flour
First recorded in 1880–85
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for rock flour
Nearly all of the soil in the Park is rock-flour that was ground by glaciers, and in part distributed by them.
Mountains are moved piecemeal, and are ground to boulders, pebbles, and rock-flour in the moving.
Mountains were moved piecemeal, and ground to boulders, pebbles, and rock-flour in the moving.The Spell of the Rockies
Enos A. Mills
- 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