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[muhd-stohn] /ˈmʌdˌstoʊn/
noun, Geology
a clayey rock with the texture and composition of shale but little or no lamination.
Origin of mudstone
1730-40; mud + stone Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for mudstone
  • The tracks are concentrated where the white sandstone meets the overlaying soft mudstone strata.
  • The towers have various layers of rock, including sandstone and mudstone.
  • Over time, these sediment layers hardened into sandstone and mudstone and even harder ironstone, piling on the protection.
  • Elisa walked up the side canyon with its weird mudstone walls, the rocks too hot to touch.
  • Commonly cliff-forming, cross-bedded sandstone lenses alternating with slope-forming siltstone, mudstone and shale.
British Dictionary definitions for mudstone


a dark grey clay rock similar to shale but with the lamination less well developed
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
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mudstone in Science
A fine-grained, dark gray sedimentary rock consisting primarily of compacted and hardened silt and clay, similar to shale but without laminations. The proportions of silt and clay in mudstone are approximately equal.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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