depths
121earthquake — /errth kwayk /, n. 1. a series of vibrations induced in the earth s crust by the abrupt rupture and rebound of rocks in which elastic strain has been slowly accumulating. 2. something that is severely disruptive; upheaval. [1300 50; ME erthequake …
122echinoderm — /i kuy neuh derrm , ek euh neuh /, n. any marine animal of the invertebrate phylum Echinodermata, having a radiating arrangement of parts and a body wall stiffened by calcareous pieces that may protrude as spines and including the starfishes, sea …
123literature — /lit euhr euh cheuhr, choor , li treuh /, n. 1. writings in which expression and form, in connection with ideas of permanent and universal interest, are characteristic or essential features, as poetry, novels, history, biography, and essays. 2.… …
124mollusk — molluskan, molluscan /meuh lus keuhn/, adj., n. mollusklike, adj. /mol euhsk/, n. any invertebrate of the phylum Mollusca, typically having a calcareous shell of one, two, or more pieces that wholly or partly enclose the soft, unsegmented body,… …
125natural gas — a combustible mixture of gaseous hydrocarbons that accumulates in porous sedimentary rocks, esp. those yielding petroleum, consisting usually of over 80 percent methane together with minor amounts of ethane, propane, butane, nitrogen, and,… …
126commercial fishing — Introduction the taking of fish and other seafood and resources from oceans, rivers, and lakes for the purpose of marketing them. Fishing is one of the oldest employments of humankind. Ancient heaps of discarded mollusk shells (shell… …
127Earth exploration — Introduction the investigation of the surface of the Earth and of its interior. By the beginning of the 20th century most of the Earth s surface had been explored, at least superficially, except for the Arctic and Antarctic regions. Today the… …
128undersea exploration — Introduction the investigation and description of the ocean waters and the seafloor and of the Earth beneath. Primary objectives and accomplishments Included in the scope of undersea exploration are the physical and chemical… …
