| OCR Text |
Show 196 FISH The distribution and speciation of the fish of the study area have been greatly influenced by Pleistocene Lake Bonneville and physiographical changes that have occurred since the beginning of Pleistocene in the Great Basin. The following information from Hubbs and Miller ( 1948) gives an insight into these influences. They state that, " Whether reviewed through the eyes of physiographers and glacial geologists or through those of biologists, the Great Basin is a land of relicts." Throughout the generally arid expanses between the crests of the Wasatch and Sierra Nevada ranges, physiographers find remnants of water and moist land. In these areas, biologists find isolated populations of plants and animals. Physiographers say that the Great Basin was a well- watered land in the geologically near past, and biologists have much evidence that those isolated life- forms were interconnected. Evidentally, the desert areas separating those water- associated plants and animals were sufficiently moist and cool to permit passage of those organisms. Evidence of the abundant water once present in the deserts is clear to any keen observer. There are shore features of ancient lakes around many enclosed basins far above the level of ephemeral lakes and plazas. There are distinct cuts in the dry terrain made by long runners and numerous travertine deposits giving evidence of hot springs. Geologists agree that the last Pleuvial period favored conditions for the wide dispersal of faunas and floras. It was probably during that time that fish populations reached the remote springs and creeks where they are now found. |
