Search

Search results

Displaying 1 - 10

Permian period

(Encyclopedia) Permian periodPermian periodpûrˈmēən [from Perm, Russia], sixth and last period of the Paleozoic era (see Geologic Timescale, tablegeologic timescale, table) from 250 to 290 million…

Mesolithic period

(Encyclopedia) Mesolithic periodMesolithic periodmĕzˌəlĭthˈĭk [key] or Middle Stone Age, period in human development between the end of the Paleolithic period and the beginning of the Neolithic…

period, in geologic time

(Encyclopedia) period, unit of time on the geologic timescale. Periods are shorter than an era and longer than an epoch. Periods are of variable length, generally lasting tens of millions of years,…

Pleistocene epoch

(Encyclopedia) Pleistocene epochPleistocene epochplīˈstəsēn, 6th epoch of the Cenozoic era of geologic time (see Geologic Timescale, tablegeologic timescale, table). According to a classification…

glacial periods

(Encyclopedia) glacial periods, times during which large portions of the earth's surface were covered with thick glacial ice sheets. In the Pleistocene epoch, in the Carboniferous and Permian periods…

Transandine Railway

(Encyclopedia) Transandine Railway, former rail line, 156 mi (251 km) long, between Mendoza, Argentina, and Los Andes, Chile, traversing the Andes at Uspallata Pass. Opened to traffic in 1910, the…

epoch

(Encyclopedia) epoch, unit of geologic time that is a subdivision of a period. The Pleistocene and Holocene epochs, for example, are divisions of the Quaternary period. Epoch is also used to describe…

Table of Geological Periods

It is generally assumed that planets are formed by the accretion of gas and dust in a cosmic cloud, but there is no way of estimating the length of this process. Our Earth acquired its present size…

boulder, in geology

(Encyclopedia) boulder, large rock fragment formed by detachment from its parent consolidated rock by weathering and erosion. In engineering and geology, especially in the United States, the term is…