Definition of "geologic time" []

• The period of time covering the physical formation and development of Earth, especially the period prior to human history. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "There were a few such cavernous ledges in the woods on my father's farm where one could retreat from a sudden shower, but less than a mile away there were two lines of them, one on Pine Hill and one on Chase's Hill, where the foundations of the earth were laid open, presenting a broken and jagged rocky front from ten to thirty or forty feet high, gnawed full of little niches and pockets and cavernous recesses by the never-dulled tooth of geologic time and affording dens and retreats where Indians and wild beasts often took refuge."