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Precambrian
(Encyclopedia)Precambrian, name of a major division of geologic time (see Geologic Timescale, tablegeologic timescale, table), from c.5 billion to 570 million years ago. It is now usually divided into the Archean a...Keewatin
(Encyclopedia)Keewatin: see Precambrian.Archean eon
(Encyclopedia)Archean eon: see Precambrian.Proterozoic eon
(Encyclopedia)Proterozoic eon: see Precambrian. ...Coutchiching
(Encyclopedia)Coutchiching ko͞oˌchĭchĭngˈ [key]: see Precambrian. ...Arbuckle Mountains
(Encyclopedia)Arbuckle Mountains ärˈbŭkəl [key], range of low, rolling hills, rising c.700 ft (210 m) above the prairie, S Okla.; remnant of mountains formed in the Precambrian. Interesting geological formation...stromatolite
(Encyclopedia)stromatolite, layered structures produced by the binding together of sediments by a thin layer of cyanobacteria. The layers, which are deposited very slowly, gradually produce rounded or hummocklike f...Siberian Platform
(Encyclopedia)Siberian Platform or Angara Shield, large, geologically stable area of Precambrian rocks, N Asia, comprising much of Siberia, Russia. It is bounded, in general, on the west by the Yenisei River, on th...Baltic Shield
(Encyclopedia)Baltic Shield, the continental core of Europe, composed of Precambrian crystalline rock, the oldest of Europe. The tectonically stable region was not affected by the Caledonian, Hercynian, and Alpine ...Logan, Sir William Edmond
(Encyclopedia)Logan, Sir William Edmond, 1798–1875, Canadian geologist. Educated in England, he managed (1831–38) coal mines and a copper smelter in Wales. In addition to making studies of clays underlying coal...Browse by Subject
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