Information about recent geologic activity is necessary to understand the rates, magnitude, and processes of environmental change along the river today. Although the dam provided a reliable water source for millions of Americans, rising waters obscured the geology and archeology of the Glen The story begins almost two billion years ago with the formation of … Standing at about the center of this vast volcanic field are the prominent San Francisco Peaks of Flagstaff, Arizona, remnants of a geologically young stratovolcano. Glen Canyon National Recreation Area (shortened to Glen Canyon NRA or GCNRA) is a recreation and conservation unit of the United States National Park Service that encompasses the area around Lake Powell and lower Cataract Canyon in Utah and Arizona, covering 1,254,429 acres (5,076.49 km 2) of mostly rugged high desert terrain. This report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. These prehistoric floods were substantially larger than the largest historic flood of July 1884, on the basis of the elevation of the deposits above the historic-age flood deposits. U.S. Geological Survey REGIONAL GEOLOGY. To set the stage for the region’s amazing landscape The Hualapai Limestone was deposited in a warm, shallow freshwater lake just west of the Grand Wash Cliffs. The higher the gradient, the steeper the slope. The ultimate base level is sea level (0 ft.). Changes in streamflow at the gaging stations are described by Andrews (1990; 1991). Its distinctive features allow researchers to piece together the history of this unique location, one of America’s treasures and a UNESCO World Heritage Site. Thinking of the geologic record as a book is helpful to understand each page of Earth’s history. Hereford, R., Burke, K.J., and Thompson, K.S., 2000, Map showing Quaternary geology and geomorphology of the Lees Ferry area, Glen Canyon, Arizona: U.S. Geological Survey Geologic Investigations Series I–2663, scale 2,000, available at https://pubs.usgs.gov/imap/i2663/. Download the latest version of Adobe Reader, free of charge. Since the completion of the Glen Canyon Dam in 1963, the once warm and muddy Colorado River has run clear and cold, with a drastically altered ecosystem. How has the Glen Canyon Dam changed the Colorado River's flow? The first written description of the area is the Dominguez- Escalante Journal (Chavez, 1976, p. 93–95), an account of an expedition through the Southwest in 1776. The $5.8 million Glen Canyon Park Playground improvements were funded by the 2008 Clean and Safe Neighborhood Parks Bond, with additional support from The Trust for Public Land and the California Coastal Conservancy. Directly below the Sandy Point Basalt rests a Colorado River gravel deposit. For riverbeds, a high, or steep, gradient means a faster current. Carol Hill of the University of New Mexico recently proposed that the “ancestral” Colorado River integrated with the young Colorado through the collapse of a groundwater-karst system. CHAPTER 11. In addition, the terrace sequence in the Lees Ferry area is similar to a dated terrace sequence in eastern Grand Canyon and Marble Canyon (Hereford, 1996; Hereford and others, 1993; 1996a; 1998), which permits correlation with the dated alluvium. Currently controlled by Glen Canyon Dam, the Colorado River through Grand Canyon no longer experiences dramatic changes in water volume throughout the year. In northeast Arizona (Black Mesa basin), the Glen Canyon is divided into (ascending): Wingate Sandstone, Kayenta Formation, and Navajo Sandstone. To address this, high-flow Glen Canyon National Recreation Area (shortened to Glen Canyon NRA or GCNRA) is a recreation and conservation unit of the United States National Park Service that encompasses the area around Lake Powell and lower Cataract Canyon in Utah and Arizona, covering 1,254,429 acres (5,076.49 km 2) of mostly rugged high desert terrain. The Paria River, an important tributary, enters the Lees Ferry area through Paria Canyon (fig. If you go sledding, a steeper slope means a faster ride down the hill. Water has tremendous erosive power, particularly when carrying large amounts of sediment and rock, like the Colorado River does when flooding. Readers will experience the intrigue and beauty of the Canyon while following not only the story of an individual but also of Glen Canyon itself. Numerous normal faults cut across Grand Canyon. Mechanical weathering happens relatively quickly in arid regions. 2). U.S. Geological Survey Geologic Investigations Series I–2663. U.S. Geological Survey Gradient is a measure of slope. This information is also needed to evaluate the consequences of regulated streamflow, which began in 1963 with closure of Glen Canyon Dam (27 km upstream of the map area). This is a very new idea and it is still being developed. A new plan to release regular, intentional floods — to resupply sediment and restore species habitat — aims to reverse the damage done to the Grand Canyon’s natural systems over the last 50 years. The deposits were mapped in the field using low-altitude (scale 1: 4800) color aerial photographs taken May 30, 1993. The view is to the south in the direction the river flows and captures Lees Ferry, the historic crossing of the river from 1864 to 1929. Some believe the Bouse Formation was deposited in an estuary, while others claim that deposition took place in a series of freshwater lakes fed by the Colorado. The Grand Canyon tells one of the world’s greatest geologic stories. Grand Canyon is the result of a distinct and ordered combination of geologic events. The geopolitical boundary or Compact Point between the Upper and Lower Colorado River Basin is in the Lees Ferry area. Connecting the Colorado River of the Colorado Plateau with an outlet to the sea lowered the base level by about 5,000 feet (1,524 m). Since before the gates at Glen Canyon Dam were closed in 1964, Glen Canyon has been capturing and releasing sediment from the Upper Colorado River Basin watershed to … Lee's Ferry, Arizona | The Colorado River exits Glen Canyon (bottom) and begins its entry into Grand Canyon (far right). The year is 2009 when the wife and I took our puppies down to go camping at Lake Powell, also known as the Glen Canyon NRA. Last modified March 21, 2012 Policies and Notices, U.S. Department of the Interior | A few geologists have hypothesized that the ancestral Colorado River was temporarily dammed behind the Kaibab Plateau and other high points. Geologic mapping was undertaken to provide information about the age, distribution, and origin of surficial deposits in the near-river environment. The resulting essentially clear water flows are erosive in a river system formerly adjusted to a large supply of sandsize sediment. The Colorado River flows through an Arid Climate. It does not contain any river sediments, therefore, the Colorado River was not flowing yet when the Hualapai Limestone was deposited. The aerial photographs are numbered GCES 10–6 to 10–8 and 11–1 to 11–8. URL: https://pubs.usgs.gov/imap/i2663/ (Blakey, 2008) Early Jurassic, 199.6 million years ago to … Accessibility Glen Canyon Group Jurassic Mesozoic stratigraphy Triassic United States age designations reappraised Latitude & Longitude N33 40'00" - N40 30'00", W114 00'00" - … In terms of surficial geology, the late Quaternary deposits shown on the map record the physical effects of environmental change on the Colorado River, the Paria River, and the relatively small tributaries draining the rim of Glen Canyon. In late 1871, the now abandoned ferry crossing (on the debris fan near the east boundary of the map area) was established by John D. Lee who also settled Lonely Dell Ranch (north of map area). The Imperial Formation is composed of both marine and deltaic sediments, meaning that it was deposited at the mouth of a river on a delta that was sometimes covered by the sea. Geology of the National Parks Through Pictures - Glen Canyon NRA My next post about the Geology of the National Parks Through Pictures was another one long ago. The expedition camped on the banks of the Paria River near the former junction with the Colorado River (fig. Glen Canyon Dam, completed in 1964, is anchored in Jurassic Navajo Sandstone, the oldest formation exposed in the map area. Canyon entrenchment and widening via stream erosion (primarily floods) and mass wasting (primarily landslides and rockfall) create the principal geologic hazards with which tourists and NPS staff must contend. Page Last Modified: Wednesday, November 30, 2016, 05:38:14 PM, Download the latest version of Adobe Reader, free of charge. Hualapai Limestone (6 - 11 million years ago), Sandy Point Basalt (4.4 million years ago), Imperial Formation (4.3 - 5 million years ago), Opening of the Gulf of California (~ 5.5 million years ago), Spillover Theory - the Catastrophic Draining of Ancient Lakes. It occupies about 70 acres (28 ha) along a deep canyon adjacent to the Glen Park, Diamond Heights, and Miraloma Park[2] neighborhoods. Above these old rocks lie layer upon layer of sedimentary rock, each telling a unique part of the environmental history of the Grand Canyon region. That is, there is a lot of water flowing in the Colorado River. Grand Canyon is the result of a distinct and ordered combination of geologic events. (a) Physiography.- Glen Canyon Dam is situated in the Colorado Plateau province, a vast area of nearly horizontal beds … The traditional view of canyon erosion holds that river incision, driven by tectonics, climatic perturbations, or changes in substrate erodibility, lowers the canyon bottom. Plates pull apart along divergent plate boundaries. In 1963 begonnen Glen Canyon Dam en andere dammen verder stroomopwaarts de stroom van de Colorado-rivier door Grand Canyon te reguleren. The quartz-rich sands and silts of the Bouse Formation are found in just three basins along the modern Colorado River. This report is also available in print from. Stretching from the beginning of the Grand Canyon at Lees Ferry in Arizona to the Orange Cliffs of southern Utah, Glen Canyon National Recreation Area is an unparalleled location for water-based and backcountry recreation. Ground control for photogrammetric construction of the topographic base map was done by the Surveying Team of the Bureau of Reclamation, Glen Canyon Environmental Studies (GCES). As the glacier moves, the rocks and sediment grind and scrape the rock surfaces over which the ice flows. In southwest Utah and northwest Arizona (Plateau sedimentary and Great Basin provinces), the Glen Canyon Group is divided into (ascending): Moenave Formation, Kayenta Formation, and Navajo Sandstone. Erosional geologic processes dominate the Glen Canyon region. Debris- flow deposits in the map area were subdivided on the basis of the degree of sur face weathering and darkness of rock varnish, which was deter mined using the method of Bull (1991, p. 63–64).