hardpan

[ hahrd-pan ]
/ ˈhɑrdˌpæn /

noun

any layer of firm detrital matter, as of clay, underlying soft soil.Compare caliche, duricrust.
hard, unbroken ground.
the fundamental or basic aspect of anything; solid foundation; underlying reality: the hardpan of mathematical theory.

Origin of hardpan

An Americanism dating back to 1810–20; hard + pan1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for hardpan

British Dictionary definitions for hardpan

hardpan

/ (ˈhɑːdˌpæn) /

noun

a hard impervious layer of clay below the soil, resistant to drainage and root growth
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

Science definitions for hardpan

hardpan

[ härdpăn′ ]

A hard, usually clay-rich layer of soil lying at or just below the ground surface, in which soil particles are cemented together by silica, iron oxide, calcium carbonate, or organic matter that has precipitated from water percolating through the soil. Hardpans do not soften when exposed to water. Also called caliche
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.