. Animal Ecology. Animal ecology. >m'. FIG. the 1 -2 Conjectural map of vegetation in North An e of the maximum Wisconsin glaciation (from (Moreau 1933). Lakes Bonneville and Lahontan, as well as many smaller ones, were formed in the Great Basin of North America during these pluvial periods (Meinzer 1922, Hubbsand Miller 1948). There was considerable alteration of drainage pat- terns over the northern part of the continent. Old river valleys were filled or dammed by ice or mo- raines. New outlets were formed. Rivers previously separated became connected. The retreat of the gla- cier left va
. Animal Ecology. Animal ecology. >m'. FIG. the 1 -2 Conjectural map of vegetation in North An e of the maximum Wisconsin glaciation (from (Moreau 1933). Lakes Bonneville and Lahontan, as well as many smaller ones, were formed in the Great Basin of North America during these pluvial periods (Meinzer 1922, Hubbsand Miller 1948). There was considerable alteration of drainage pat- terns over the northern part of the continent. Old river valleys were filled or dammed by ice or mo- raines. New outlets were formed. Rivers previously separated became connected. The retreat of the gla- cier left vast level areas without drainage so that many lakes, swamps, and bogs remain in northern glaciated areas. In other places the large quantities of melt water cut new channels or widened old val- leys, through which the surplus water was trans- ported to the sea. Silt, sand, and gravel were spread out in outwash plains, from which winds picked up the finer material and deposited it elsewhere as loess in layers up to or 3 meters thick (100 in.) over hundreds of square kilometers. The treatise of Thienemann (1950) is an extensive account of what happened to the fresh-water fauna. Deciduous forest lllllll Coniferous forest •'.•/.? Desert Glacier IV; Grassland Bd forest ?V. Tundra tlon given by Flint 1952, 1957, Meinier 1922, Hobbs 1950. Braun 1950, Hansen 1947). Terrestrial biota and communities Virtually all the fossil plants and mollusks dur- ing the Pleistocene are represented by living relatives (Baker 1920). Changes of ecological significance are, for the most part, in point of geographic dis- tribution rather than organic evolution. But insects, especially beetles, which are well represented in the fossil record evolved rapidly into new forms. Many mammals became extinct. Large mammals present during early stages of the Pleistocene, but no longer occurring in North America, include camels, horses (one species later re-introduced), ground sloths, two
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Keywords: ., bookcentury1900, bookcollectionbiodive, booksubjectanimalecology
