A summit is a point on a surface that is higher in elevation than all points immediately adjacent to it. Mathematically, a summit is a maximum in elevation. The topographic terms acme, apex and zenith are synonymous, the UIAA definition is that a summit is independent if it has a prominence of 30 metres or more, it is a mountain if it has a prominence of at least 300 metres. This can be summarised as follows, A pyramidal peak is an exaggerated form produced by ice erosion of a mountain top, Summit may refer to the highest point along a line, trail, or route. In many parts of the western United States, the term refers to the highest point along a road, highway. For example, the highest point along Interstate 80 in California is referred to as Donner Summit while the highest point on Interstate 5 is Siskiyou Mountain Summit, geoid Hill List of highest mountains Maxima and minima Nadir Summit accordance Peak finder
The Colorado River is one of the principal rivers of the Southwestern United States and northern Mexico. The 1, 450-mile-long Colorado River drains an expansive, arid watershed that encompasses parts of seven U. S. starting in the central Rocky Mountains in the U. S. After entering Mexico, the Colorado approaches the mostly dry Colorado River Delta at the tip of the Gulf of California between Baja California and Sonora. Known for its dramatic canyons, whitewater rapids, and eleven U. S. National Parks, the Colorados large flow and steep gradient are used for generating hydroelectric power, and its major dams regulate peaking power demands in much of the Intermountain West. Intensive water consumption has dried up the lower 100 miles of the river, beginning with small bands of nomadic hunter-gatherers, Native Americans have inhabited the Colorado River basin for at least 8,000 years. Most native peoples that inhabit the basin today are descended from groups that settled in the region beginning about 1,000 years ago.
Europeans first entered the Colorado Basin in the 16th century, when explorers from Spain began mapping and claiming the area, early contact between Europeans and Native Americans was generally limited to the fur trade in the headwaters and sporadic trade interactions along the lower river. After most of the Colorado River basin became part of the U. S. in 1846, several expeditions charted the Colorado in the mid-19th century – one of which, led by John Wesley Powell, was the first to run the rapids of the Grand Canyon. American explorers collected valuable information that would be used to develop the river for navigation, lesser numbers settled in the upper basin, which was the scene of major gold strikes in the 1860s and 1870s. Large engineering works began around the start of the 20th century, with guidelines established in a series of international. The U. S. federal government was the driving force behind the construction of dams and aqueducts in the river system, although many state.
Most of the dams in the river basin were built between 1910 and 1970, the system keystone, Hoover Dam, was completed in 1935. The Colorado is now considered among the most controlled and litigated rivers in the world, as demands for Colorado River water continue to rise, the level of human development and control of the river continues to generate controversy. The Colorado begins at La Poudre Pass in the Southern Rocky Mountains of Colorado, after a short run south, the river turns west below Grand Lake, the largest natural lake in the state. As it flows southwest, it gains strength from many tributaries, as well as larger ones including the Blue, Eagle. In a few areas, such as the marshy Kawuneeche Valley near the headwaters, arcing northwest, the Colorado begins to cut across the eponymous Colorado Plateau, a vast area of high desert centered at the Four Corners of the southwestern United States. In Utah, the Colorado flows primarily through the slickrock country and this is one of the most inaccessible regions of the continental United States.
Here, the San Juan River, carrying runoff from the slope of Colorados San Juan Mountains, joins the Colorado from the east. S
Lower Colorado River Valley
Five Indian reservations are located in the LCRV, the Chemehuevi, Fort Mojave and Colorado River Indian Reservations, at Yuma are the Quechan and Cocopah reservations. Worldwide, only some deserts found in Africa and in the Middle East stand up with a hotter summer climate on average. The LCRV is defined by three deserts, the Mojave Desert is in southeast California, southern Nevada, and northwest Arizona. To the south is the Sonoran Desert on both sides of the Colorado River, the LCRV extends about 350 miles from Hoover Dam to the Colorado River Delta. The Sonoran Desert itself is more than twice as extensive north-to-south, two species, Desert Ironwood- and the Lesser Long-nosed Bat, have geographic ranges identical to the Sonoran Desert, and are indicator species of the Sonoran Desert region. The spring flowering of Ironwood, and the bat species migration arrivals become indicators of annual or multi-year climate trends for regions of the Sonoran Desert, the Lower Colorado River Valley subregion of the Sonoran Desert bioregion has multiple threats.
Some major threats include urbanization, clearing of land for agriculture, human occupancy – especially as a result of imported external resources, rio Grande Valleys List of dams of the LCRV List of LCRV communities Little. Atlas of United States Trees, Volume 3, Minor Western Hardwoods, Elbert L,1976, US Bureau of Reclamation, Dams Along the Lower Colorado River
California is the most populous state in the United States and the third most extensive by area. Located on the western coast of the U. S, California is bordered by the other U. S. states of Oregon and Arizona and shares an international border with the Mexican state of Baja California. Los Angeles is Californias most populous city, and the second largest after New York City. The Los Angeles Area and the San Francisco Bay Area are the nations second- and fifth-most populous urban regions, California has the nations most populous county, Los Angeles County, and its largest county by area, San Bernardino County. The Central Valley, an agricultural area, dominates the states center. What is now California was first settled by various Native American tribes before being explored by a number of European expeditions during the 16th and 17th centuries, the Spanish Empire claimed it as part of Alta California in their New Spain colony. The area became a part of Mexico in 1821 following its war for independence.
The western portion of Alta California was organized as the State of California, the California Gold Rush starting in 1848 led to dramatic social and demographic changes, with large-scale emigration from the east and abroad with an accompanying economic boom. If it were a country, California would be the 6th largest economy in the world, fifty-eight percent of the states economy is centered on finance, real estate services and professional, scientific and technical business services. Although it accounts for only 1.5 percent of the states economy, the story of Calafia is recorded in a 1510 work The Adventures of Esplandián, written as a sequel to Amadis de Gaula by Spanish adventure writer Garci Rodríguez de Montalvo. The kingdom of Queen Calafia, according to Montalvo, was said to be a land inhabited by griffins and other strange beasts. This conventional wisdom that California was an island, with maps drawn to reflect this belief, shortened forms of the states name include CA, Cal. Calif. and US-CA.
Settled by successive waves of arrivals during the last 10,000 years, various estimates of the native population range from 100,000 to 300,000. The Indigenous peoples of California included more than 70 distinct groups of Native Americans, ranging from large, settled populations living on the coast to groups in the interior. California groups were diverse in their organization with bands, villages. Trade and military alliances fostered many social and economic relationships among the diverse groups, the first European effort to explore the coast as far north as the Russian River was a Spanish sailing expedition, led by Portuguese captain Juan Rodríguez Cabrillo, in 1542. Some 37 years English explorer Francis Drake explored and claimed a portion of the California coast in 1579. Spanish traders made unintended visits with the Manila galleons on their trips from the Philippines beginning in 1565
United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its resources. The organization has four science disciplines, concerning biology, geology. The USGS is a research organization with no regulatory responsibility. The USGS is a bureau of the United States Department of the Interior, the USGS employs approximately 8,670 people and is headquartered in Reston, Virginia. The USGS has major offices near Lakewood, Colorado, at the Denver Federal Center, the current motto of the USGS, in use since August 1997, is science for a changing world. The agencys previous slogan, adopted on the occasion of its anniversary, was Earth Science in the Public Service. Prompted by a report from the National Academy of Sciences, the USGS was created, by a last-minute amendment and it was charged with the classification of the public lands, and examination of the geological structure, mineral resources, and products of the national domain.
This task was driven by the need to inventory the vast lands added to the United States by the Louisiana Purchase in 1803, the legislation provided that the Hayden and Wheeler surveys be discontinued as of June 30,1879. Clarence King, the first director of USGS, assembled the new organization from disparate regional survey agencies, after a short tenure, King was succeeded in the directors chair by John Wesley Powell. Administratively, it is divided into a Headquarters unit and six Regional Units, Other specific programs include, Earthquake Hazards Program monitors earthquake activity worldwide. The National Earthquake Information Center in Golden, Colorado on the campus of the Colorado School of Mines detects the location, the USGS runs or supports several regional monitoring networks in the United States under the umbrella of the Advanced National Seismic System. The USGS informs authorities, emergency responders, the media, and it maintains long-term archives of earthquake data for scientific and engineering research.
It conducts and supports research on long-term seismic hazards, USGS has released the UCERF California earthquake forecast. The USGS National Geomagnetism Program monitors the magnetic field at magnetic observatories and distributes magnetometer data in real time, the USGS operates the streamgaging network for the United States, with over 7400 streamgages. Real-time streamflow data are available online, since 1962, the Astrogeology Research Program has been involved in global and planetary exploration and mapping. USGS operates a number of related programs, notably the National Streamflow Information Program. USGS Water data is available from their National Water Information System database
Traditional definitions require a topographic map to show both natural and man-made features. A topographic map is published as a map series, made up of two or more map sheets that combine to form the whole map. A contour line is a line connecting places of equal elevation, however, in the vernacular and day to day world, the representation of relief is popularly held to define the genre, such that even small-scale maps showing relief are commonly called topographic. The study or discipline of topography is a broader field of study. Topographic maps are based on topographical surveys, performed at large scales, these surveys are called topographical in the old sense of topography, showing a variety of elevations and landforms. This is in contrast to older cadastral surveys, which primarily show property, the first multi-sheet topographic map series of an entire country, the Carte géométrique de la France, was completed in 1789. Topographic surveys were prepared by the military to assist in planning for battle, as such, elevation information was of vital importance.
As they evolved, topographic map series became a resource in modern nations in planning infrastructure. Excluding borders, each sheet was 44 cm high and up to 66 cm wide, although the project eventually foundered, it left an indexing system that remains in use. TIGER was developed in the 1980s and used in the 1990, digital elevation models were compiled, initially from topographic maps and stereographic interpretation of aerial photographs and from satellite photography and radar data. Since all these were government projects funded with taxes and not classified for security reasons. Initial applications were mostly professionalized forms such as innovative surveying instruments, by the mid-1990s, increasingly user-friendly resources such as online mapping in two and three dimensions, integration of GPS with mobile phones and automotive navigation systems appeared. As of 2011, the future of standardized, centrally printed topographical maps is left somewhat in doubt, the various features shown on the map are represented by conventional signs or symbols.
For example, colors can be used to indicate a classification of roads and these signs are usually explained in the margin of the map, or on a separately published characteristic sheet. Topographic maps are commonly called contour maps or topo maps. In the United States, where the national series is organized by a strict 7. 5-minute grid. Topographic maps conventionally show topography, or land contours, by means of contour lines, contour lines are curves that connect contiguous points of the same altitude. In other words, every point on the line of 100 m elevation is 100 m above mean sea level
Imperial County, California
Imperial County is a county in the U. S. state of California. As of the 2010 census, the population was 174,528, the county seat is El Centro. Established in 1907, it was the last county to be formed in California, Imperial County comprises the El Centro, CA Metropolitan Statistical Area. It is part of the Southern California border region, the smallest but most economically diverse region in the state and it is located in the Imperial Valley, in the far southeast of California, bordering both Arizona and Mexico. The Imperial Valley is a pot of Anglo-American and Chicano/Latino cultures. On the American side, the majority of residents are of Mexican American heritage, the entire valley is a multi-ethnic mixture of whites, Asian Americans, some African Americans and Native Americans. In 2014, Imperial County had the second highest percentage of unemployed people of any county in the United States, Spanish explorer Melchor Díaz was one of the first Europeans to visit the area around Imperial Valley in 1540.
The explorer Juan Bautista de Anza explored the area in 1776, years later, after the Mexican-American War, the northern half of the valley was annexed by the U. S. while the southern half remained under Mexican rule. Small scale settlement in natural aquifer areas occurred in the early 19th century, in 1905, torrential rainfall in the American Southwest caused the Colorado River to flood, including canals that had been built to irrigate the Imperial Valley. Since the valley is partially below sea level, the waters never fully receded, but collected in the Salton Sink in what is now called the Salton Sea, Imperial County was formed in 1907 from the eastern portion of San Diego County. Much of the Imperial Land Companys land existed in Mexico, the objective of the company was commercial crop farming development. By 1910, the company had managed to settle and develop thousands of farms on both sides of the border. The Mexican Revolution soon after severely disrupted the companys plans, nearly 10,000 farmers and their families in Mexico were ethnically cleansed by the rival Mexican armies.
By the 1950 census, over 50,000 residents lived in Imperial County alone, most of the population was year-round but would increase every winter by migrant laborers from Mexico. Until the 1960s, the farms in Imperial County provided substantial economic returns to the company, currently, El Centro has one of the U. S highest unemployment rates and ranks one of the states poorest counties or have a lower than state and national average annual household income. Fort Yuma is located on the banks of the Colorado River in Winterhaven, first established after the end of the Mexican-American War in 1848, it was originally located in the bottoms near the Colorado River, less than 1-mile below the mouth of the Gila River. It was to defend the newly settled community of Yuma, Arizona on the side of the Colorado River. In March 1851 the post was moved to an elevation on the Colorados west bank, opposite the present city of Yuma, Arizona