Imperial County CA Archives History - Books .....The Colorado 1918 ************************************************ Copyright. All rights reserved. http://www.usgwarchives.net/copyright.htm http://www.usgwarchives.net/ca/cafiles.htm ************************************************ File contributed for use in USGenWeb Archives by: Joy Fisher sdgenweb@yahoo.com February 14, 2006, 3:32 am Book Title: History Of Imperial County California THE COLORADO This is one of the longest rivers of the world when its tributaries are included. It begins at the junction of the Grand and Green rivers in the southeastern part of Utah, the whole river being really a continuation of the Colorado in its upper part. Its mileage is about 2000, and the drainage is about 800 miles long, varying in width from 300 to 500 miles, with a total of something like 300,000 square miles. It flows through Wyoming, Colorado, Utah, Arizona, California, Nevada, New Mexico, and Mexico. The lower basin of the river is only slightly below sea level, with some mountain ranges rising 2000 and 6000 feet in the air. The upper part of this basin is from 4000 to 8000 feet above sea level, and it is bordered on the east, west and north by snow-clad mountains. Through this plateau there are deep gorges, transverse valleys and caanons which are dry most of the year. Among these and other tributaries in this district flow the waters that go to make up this sluggish and erratic river, which for untold centuries has carried down the silt and atoms of earth that were destined to transform this great Valley and make it blossom like the rose. Sluggish streams with shallow settling basins, are required to produce this cargo of maturing debris. And here the story of the formation of the Colorado, now reclaimed, and the great Imperial Valley, its daughter, begins. In 1853 government experts made exhaustive investigations of this region. After describing the bordering mountains, their report turns to the desert section, and says that it belongs to the type which physiographers describe as constructional, an area which has been depressed as a result of a crustal movement, as contrasted with valleys due to erosion. Its rock-floor or bottom is below tide even in those parts north of the Gulf where the actual surface is well below the sea. This indicates a subsidence of the earth's crust. A marked fault-line in the mountains show that the Valley simply dropped away at some time or other, either slowly or suddenly. There are therefore topographic characteristics of a faulted-block tilted toward the northeast and plunging into the desert toward the southeast. As the entire basin is occupied by lake silts and alluvium of most recent origin, it is evident that these fault-movements were of a very late period. Everything strongly points therefore to the fact that this desert valley is associated with structures in which faults are prominent. When this valley-floor subsided there must have been a great inrush of the Gulf waters. Scientists agree that at a comparatively recent geological period this section was covered by the waters of the Pacific. It was here that the Colorado found its way in past ages and tumbled its load of silt year after year, forming at last a delta near its mouth which spread in time and buried the original floor of the Gulf under hundreds of feet of mud and alluvium, and finally cut the Gulf in two by building up the delta dam which separates this Gulf depression from that known as the Salton Sink. The conclusions arrived at therefore by these government geologists are that this Colorado desert was not a desert at all at first, and only became so when the floor of the basin settled probably iooo feet, became inundated by the gulf, received the salt-laden waters of the Colorado and Gila rivers, with their numerous tributaries, thus forming a delta and lake was into which the water poured for centuries until the surface of the lake was about forty feet above the sea and extended over an area of more than 2100 square miles, and finally receded gradually year after year, shrinking away entirely, leaving a great solid bed of soil, rich alluvium and detritus from 250 to 1000 feet deep. Additional Comments: Extracted from: THE HISTORY OF IMPERIAL COUNTY CALIFORNIA EDITED BY F. C. FARR IN ONE VOLUME ILLUSTRATED Published by ELMS AND FRANKS BERKELEY, CALIFORNIA 1918 Printed by Taylor & Taylor, San Francisco File at: http://files.usgwarchives.net/ca/imperial/history/1918/historyo/colorado211nms.txt This file has been created by a form at http://www.genrecords.net/cafiles/ File size: 4.6 Kb