From - Tue Jun 19 06:38:05 2001 Return-Path: Received: from peakpeak.com (tz0027.peakpeak.com [207.174.69.27]) by gash2.peakpeak.com (8.9.3/8.9.3) with ESMTP id EAA07353; Tue, 19 Jun 2001 04:35:29 -0600 Sender: snowbear@gash2.peakpeak.com Message-ID: <3B2F2B94.3A474F41@peakpeak.com> Date: Tue, 19 Jun 2001 04:38:13 -0600 From: Pam North X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.2.12-20 i586) X-Accept-Language: en MIME-Version: 1.0 To: "Green, Guerin" , "Douglas, Laura" , "North, Pam" , Vyner Jeff , "Borg, Don" Subject: Article Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Status: X-Mozilla-Status: 8001 X-Mozilla-Status2: 00000000 X-UIDL: 391deae700001628 THE ROCKY MOUNTAINS -- COLORADO'S GEOLOGIC GIANTS by Pam North Colorado is undoubtedly one of the most beautiful states in America; its scenic grandeur is enhanced by its spectacular geology. There are three main topographic regions in Colorado, which correspond to three major, very visible geologic zones. These are: the Great Plains, the Rocky Mountains and the Colorado Plateau. Approximately forty per cent of the state is comprised of low, rolling plains on the eastern side, with the remaining area equally divided between the plateau and mountain regions. The eastern plains and western plateau are classified geologically as primarily sedimentary zones, with only minor igneous and metamorphic areas. The Rocky Mountain region is comprised of a complex assortment of igneous uplifts, metamorphic rocks, and sedimentary rocks which in some places have been elevated over 9000 feet above their original depositional levels. Colorado's current geology began in the ancient past over three billion years ago. More than a half-billion years ago in the Precambrian Era the core of the Rocky Mountains was formed in ancient ranges and later leveled by erosion. Much of Colorado was under water during a major portion of geologic time. Prior to the Permian Period 240 to 280 million years ago, the Ancestral Rocky Mountains were gradually pushed up by tectonic forces at work. A branch of these uplifted ranges ran parallel along the Colorado-Utah border, and another ran about 50 miles west of the present Rockies. The eastern branch eventually was carved away completely by erosion, the great quantities of rubble material depositing out onto the lowlands during the cycles of upheaval, becoming sedimentary rock layers that reached thicknesses of over 10,000 feet in some areas. A tremendous squeezing then uplifted the region in a great series of folds, resembling wrinkles in a carpet, as the modern Rocky Mountains formed some 65 million years ago. Along the foothills of the present Rockies, the layers of the rock debris were tilted upward (in some places totally vertical), creating unusual sandstone and other sedimentary rock features, such as those in Garden of the Gods and the Flatirons. The red color, so evident in these areas known as the Fountain Formation, is the result of the iron-ore magmas that were deposited during periods of volcanic activity. These magmas, such as hemetite and magnetite, stained the sedimentary rock as it eroded. Each successive erosion of the landscape and the submergence under successive seas had a stamp on producing the varied rock structures seen today. Near the end of the Eocene Epoch about 40 million years ago, the Rockies again raised several thousand feet. Then just before the Pleistocene Epoch about 2 million years ago, still another uplift occurred. Throughout the years rivers and streams cut canyons and deep gorges through the mountain ranges. During the Ice Age snows accumulated; glaciers formed, cutting grooves as they moved down the valleys. The water elements of rain, wind and ice carved the Rockies, a sculpturing process that continues constantly even now. Colorado rock formations are of three basic types. The igneous form (granites) make up many of the mountain peaks. The sedimentary form (limestones, sandstones and clays) is the basis of the areas on which we walk and drive everyday. The metamorphic form is evident in many of the mountain peaks and canyons. Historically a tremendous obstacle for pioneers settling the West, the Rocky Mountains today have been somewhat tamed by man and his mechanical toys, and are now an endless source of joy for Coloradans and tourists as they discover the myriad facets of beauty and wonder in this awe-inspiring mountain chain. Illustration for article: http://waterknowledge.colostate.edu/geo_map.htm