Sedimentary rocks made of sand, called sandstone (B), are often formed from a sandy beach, like the one in (A). Ripple marks, which form as water flows back and forth over the surface with each crashing wave, are common on beaches and can become preserved in the rock. Do you see ripples in both the sandy beach (A) and the sandstone (B)? The sandstone in (B) was part of a beach over 200 million years ago in the Triassic period when dinosaurs roamed the Earth.
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Both images courtesy of Martin Miller, University of Oregon and the Earth Science World Imagebank .
Last modified January 6, 2004 by Lisa Gardiner.
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The Fall 2010 issue of The Earth Scientist
, focuses on rocks and minerals, including articles on minerals and mining, the use of minerals in society, and rare earth minerals, and includes 3 posters!
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