You know what it looks like… but what is it called?
TAKE THE QUIZ“Red - sandstone”
We have one entry that includes the term Red - sandstone.
Old Red Sandstone
noun: a thick series of fragmental chiefly sandstone rocks of nonmarine origin, predominantly red in color, and representing the Devonian system in some parts of Great Britain and elsewhere in northwestern Europe
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Merriam-Webster unabridged