Adjacent Words

trap rock definitions

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Webster's 1913 Dictionary

Trap Trap, n. [Sw. trapp; akin to trappa stairs, Dan. trappe, G. treppe, D. trap; -- so called because the rocks of this class often occur in large, tabular masses, rising above one another, like steps. See Tramp.] (Geol.) An old term rather loosely used to designate various dark-colored, heavy igneous rocks, including especially the feldspathic-augitic rocks, basalt, dolerite, amygdaloid, etc., but including also some kinds of diorite. Called also trap rock. Trap tufa, Trap tuff, a kind of fragmental rock made up of fragments and earthy materials from trap rocks.