Columbia Encyclopedia

Search results

177 results found

metamorphism

(Encyclopedia)metamorphism, in geology, process of change in the structure, texture, or composition of rocks caused by agents of heat, deforming pressure, shearing stress, hot, chemically active fluids, or a combin...

aquatint

(Encyclopedia)aquatint äˈkwətĭntˌ [key], etching technique. The plate is covered with a porous ground, or resist, through which acid bites many tiny pockmarks in the metal. If an area is to be completely white...

seismology

(Encyclopedia)seismology sīzmŏlˈəjē, sīs– [key], scientific study of earthquakes and related phenomena, including the propagation of waves and shocks on or within the earth by natural or artificially genera...

Devonian period

(Encyclopedia)Devonian period dĭvōˈnēən [key], fourth period of the Paleozoic era of geologic time between 408 and 360 million years ago (see Geologic Timescale, tablegeologic timescale, table). It was named (...

xerography

(Encyclopedia)xerography zərŏgˈrəfēˌ [key], also called electrophotography, method of dry photocopying in which the image is transferred by using the attractive forces of electric charges. A beam of light, us...

Deep Sea Drilling Project

(Encyclopedia)Deep Sea Drilling Project, U.S. program designed to investigate the evolution of ocean basins by core drilling of ocean sediments and underlying oceanic crust. Funded by the National Science Foundatio...

island

(Encyclopedia)island, relatively small body of land surrounded entirely by water. (As the oceans form a continuous mass of water on the earth's surface, all continents are islands in the strict sense of the word.) ...

hallmark

(Encyclopedia)hallmark, mark impressed on silverwork or goldwork to signify official approval of the standard of purity of the metal, also called plate mark. The hallmark was introduced by statute in England in 130...

fold

(Encyclopedia)fold, in geology, bent or deformed arrangement of stratified rocks. These rocks may be of sedimentary or volcanic origin. Although stratified rocks are normally deposited on the earth's surface in hor...

sea level

(Encyclopedia)sea level, the level of the sea, which serves as the datum used for measurement of land elevations and ocean depths. Theoretically, one would expect sea level to be a fixed and permanent horizontal su...