Topic: glacial periods

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 of the Paleozoic era era, and in Huronian time of the Precambrian era , the earth experienced an overall cooling of the climate, resulting in great ice sheets covering great portions of the oceans and continents . More or less extensive continental glaciations, or glacial advances, may have occurred at other times. The study of glacial periods owed its first impetus to the Swiss-American naturalist... Read more