Sedimentary basins are regions of Earth of long-term subsidence creating accommodation space for infilling by sediments. Sedimentary basins occur in diverse geological settings usually associated with tectonic activity. Basins formed in different plate tectonic regimes vary in their preservation potential, on oceanic crust, basins are likely to be subducted, while marginal continental basins may be partially preserved, and intracratonic basins have a high probability of preservation. As the sediments are buried, they are subjected to increasing pressure, a number of basins formed in extensional settings can undergo inversion which has accounted for a number of the economically viable oil reserves on earth which were formerly basins. Sedimentary basins form primarily in convergent and transform settings, convergent boundaries create foreland basins through tectonic compression of oceanic and continental crust during lithospheric flexure. Tectonic extension at divergent boundaries where continental rifting is occurring can create a nascent ocean basin leading to either an ocean or the failure of the rift zone.
If the lithosphere is caused to stretch horizontally, by such as ridge-push or trench-pull. The lower, hotter part of the lithosphere will flow away from the main area being stretched, whilst the upper and more brittle crust will tend to fault. The combined effect of two mechanisms is for the Earths surface in the area of extension to subside, creating a geographical depression which is often infilled with water and/or sediments. An example of a basin caused by lithospheric stretching is the North Sea – an important location for significant hydrocarbon reserves, another such feature is the Basin and Range Province which covers most of the USA state of Nevada, forming a series of horst and graben structures. Another expression of lithospheric stretching results in the formation of basins with central ridges, The Red Sea is in fact an incipient ocean. The mouth of the Red Sea is a triple junction where the Indian Ocean Ridge, Red Sea Rift. This is the place on the planet where such a triple junction in oceanic crust is exposed subaerially.
The reason for this is twofold, due to a high thermal buoyancy of the junction, if a load is placed on the lithosphere, it will tend to flex in the manner of an elastic plate. The magnitude of the lithospheric flexure is a function of the load and the flexural rigidity of the lithosphere. Flexural rigidity is in itself, a function of the mineral composition, thermal regime. The nature of the load is varied, for instance, the Hawaiian Islands chain of volcanic edifices has sufficient mass to cause deflection in the lithosphere. Deformation of the lithosphere in the plane of the earth occurs as a result of near horizontal maximum and minimum principal stresses, the resulting zones of subsidence are known as strike-slip or pull-apart basins
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
The Precambrian is the earliest period of Earths history, set before the current Phanerozoic Eon. The Precambrian is a supereon that is subdivided into three eons of the time scale. It spans from the formation of Earth about 4.6 billion years ago to the beginning of the Cambrian Period, about 541 million years ago, the Precambrian accounts for 89% of geologic time. Relatively little is known about the Precambrian, despite it making up roughly seven-eighths of the Earths history, the Precambrian fossil record is poorer than that of the succeeding Phanerozoic, and fossils from that time are of limited biostratigraphic use. This is because many Precambrian rocks have been metamorphosed, obscuring their origins, while others have been destroyed by erosion. A stable crust was apparently in place by 4,412 Ma, the term Precambrian is recognized by the International Commission on Stratigraphy as a general term including the Archean and Proterozoic eons. It is still used by geologists and paleontologists for general discussions not requiring the more specific eon names and it was briefly called the Cryptozoic eon.
A specific date for the origin of life has not been determined, carbon found in 3.8 billion year old rocks from islands off western Greenland may be of organic origin. Well-preserved microscopic fossils of bacteria older than 3.46 billion years have found in Western Australia. Probable fossils 100 million years older have been found in the same area, there is a fairly solid record of bacterial life throughout the remainder of the Precambrian. The oldest fossil evidence from that era of such complex life comes from the Lantian formation of the Ediacarian period, a very diverse collection of soft-bodied forms is found in a variety of locations worldwide and date to between 635 and 542 Ma. These are referred to as Ediacaran or Vendian biota, hard-shelled creatures appeared toward the end of that time span, marking the beginning of the Phanerozoic era. By the middle of the following Cambrian period, a diverse fauna is recorded in the Burgess Shale. The explosion in diversity of lifeforms during the early Cambrian is called the Cambrian explosion of life, while land seems to have been devoid of plants and animals and other microbes formed prokaryotic mats that covered terrestrial areas.
Evidence of the details of plate motions and other activity in the Precambrian has been poorly preserved. It is generally believed that small proto-continents existed prior to 4280 Ma, the supercontinent, known as Rodinia, broke up around 750 Ma. A number of glacial periods have been identified going as far back as the Huronian epoch, one of the best studied is the Sturtian-Varangian glaciation, around 850–635 Ma, which may have brought glacial conditions all the way to the equator, resulting in a Snowball Earth. The atmosphere of the early Earth is not well understood, most geologists believe it was composed primarily of nitrogen, carbon dioxide, and other relatively inert gases, and was lacking in free oxygen
It is the hottest desert in Mexico. It has an area of 260,000 square kilometers, the western portion of the United States–Mexico border passes through the Sonoran Desert. In phytogeography, the Sonoran Desert is within the Sonoran Floristic Province of the Madrean Region in southwestern North America, the desert contains a variety of unique and endemic plants and animals, such as the saguaro and organ pipe cactus. It is bounded on the west by the Peninsular Ranges, which separate it from the California chaparral and woodlands, to the north in California and northwest Arizona, the Sonoran Desert transitions to the colder-winter, higher-elevation Mojave, Great Basin, and Colorado Plateau deserts. To the east and southeast, the transition to the coniferous Arizona Mountains forests and Sierra Madre. To the south the Sonoran–Sinaloan transition subtropical dry forest is the zone from the Sonoran Desert to the tropical dry forests of the Mexican state of Sinaloa. The deserts sub-regions include the Colorado Desert of southeastern California, many ecologists now consider Shreves Vizcaíno and Magdalena regions, which lie on the western side of the Baja California Peninsula, to be a separate ecoregion, the Baja California Desert.
The Pinacate National Park includes the only active Erg dune region in North America, the nearest city to the Reserva de la Biosfera el Pinacate y Gran Desierto de Altar is Puerto Peñasco in the state of Sonora, Mexico. The Sonoran Desert area southeast of Tucson and near the Mexican border is vital habitat for the population of jaguars living within the United States. Many plants not only survive, but thrive in the conditions of the Sonoran Desert. Many have evolved to have specialized adaptations to the desert climate, the Sonoran Deserts biseasonal rainfall pattern results in more plant species than any other desert in the world. The Sonoran Desert includes plant genera and species from the family, palm family, cactus family, legume family. The Sonoran is the place in the world where the famous saguaro cactus grows in the wild. Cholla, hedgehog, prickly pear, nightblooming cereus, creosote bush and bur sage dominate valley floors. Indigo bush and Mormon tea are other shrubs that may be found, wildflowers of the Sonoran Desert include desert sand verbena, desert sunflower, and evening primroses.
Ascending from the valley up bajadas, various such as velvet mesquite, palo verde, desert ironwood, desert willow. Shrubs found at higher elevations include whitethorn acacia, fairy duster, in the desert subdivisions found on Baja California, cardon cactus, elephant tree, and boojum tree occur. The California fan palm is found in the Colorado Desert section of the Sonoran Desert and it is found at spring-fed oases, such as in Anza Borrego Desert State Park, Joshua Tree National Park, and the Kofa National Wildlife Refuge
Riverside County, California
Riverside County, California is one of fifty-eight counties in the U. S. state of California. As of the 2010 census, the population was 2,189,641, making it the 4th-most populous county in California, the name was derived from the city of Riverside, which is the county seat. Riverside County is included in the Riverside-San Bernardino-Ontario, CA Metropolitan Statistical Area, the county is included in the Los Angeles-Long Beach, CA Combined Statistical Area. There is a concentration of sprawling tract housing communities around Riverside and along the Interstate 10,15. Roughly rectangle-shaped, Riverside County covers 7,208 square miles in Southern California, the county is mostly desert in the central and eastern portions, but has a Mediterranean climate in the western portion. Most of Joshua Tree National Park is located in the county, the resort cities of Palm Springs, Palm Desert, Indian Wells, La Quinta, Rancho Mirage, and Desert Hot Springs are all located in the Coachella Valley region of Riverside County.
Large numbers of Los Angeles area workers have moved to the county in recent years to take advantage of affordable housing. Along with neighboring San Bernardino County, it was one of the fastest growing regions in the prior to the recent changes in the regional economy. In addition, but significant, numbers of people have been moving into Southwest Riverside County from the San Diego-Tijuana metropolitan area, the cities of Temecula and Murrieta accounted for 20% of the increase in population of the county between 2000 and 2007. The indigenous peoples of what is now Riverside County are the Luiseño, Cupeño, the Luiseño lived in the Aguanga and Temecula Basins, Elsinore Trough and eastern Santa Ana Mountains and southward into San Diego County. The Cahullia lived to the east and north of the Luiseño in the valleys, Santa Rosa and San Jacinto Mountains. The first European settlement in the county was a Mission San Luis Rey de Francia estancia or farm and grapes were grown here. In 1819, the Mission granted land to Leandro Serrano, mayordomo of San Antonio de Pala Asistencia for the Mission of San Luis Rey for Rancho Temescal, following Mexican independence and the 1833 confiscation of Mission lands, more ranchos were granted.
New Mexican colonists founded the town of La Placita on the east side of the Santa Ana River at the extremity of what is now the city of Riverside in 1843. When the initial 27 California counties were established in 1850 the area known as Riverside County was divided between Los Angeles County and San Diego County. In 1853 the eastern part of Los Angeles County was used to create San Bernardino County, between 1891 and 1893 several proposals, and legislative attempts, were put forth to form new counties in Southern California. These proposals included one for a Pomona County and one for a San Jacinto County, none of the proposals were adopted until a measure to create Riverside County was signed by Governor Henry H. Markham on March 11,1893. The new county was created from parts of San Bernardino County, on May 2,1893, seventy percent of voters approved the formation of Riverside County
While thin-skinned deformation is common in many different localities, thick-skinned deformation requires much more strain to occur and is a rarer type of deformation. Deformation in geology refers to any alterations to the size or shape of a rock formation since the time of its creation, there are many different ways deformation can occur but it is always the result of some amount of stress within a formation. This stress leads to the formation of structures that can either extend or shorten the length of the crust in the area. Some of the most common structures are faults and folds, thick-skinned deformation is a specific type of deformation that can take the form of either faults or folds. Thin-skinned deformation is the counterpart to thick-skinned deformation and can frequently be found in similar areas, as the term implies, thin-skinned deformation is deformation that only affects the upper layers of the cover rocks and does not continue into the deeper basement. There is one term which may be used as an intermediary between these two extremes.
The term basement-involved thin-skinned deformation can be applied to deformation that affects the cover rocks, thick-skinned deformation is most commonly a result of crustal shortening and occurs when the region is undergoing horizontal compression. This frequently occurs in at the sites of continental collisions where orogenesis, or mountain building, is taking place and during which the crust is shortened horizontally, the massive compressional forces involved in such a collision cause the basement rock and all of the units above it to deform. Deformation occurs in the form of both folds and thrust faults and may form a fold and thrust belt along the zone or as crustal flow. As the two continents are pushed together by tectonic processes a large amount of stress is put on the rock, eventually deformation will occur in one or multiple ways in order to relieve the stress. Folding usually occurs in areas with a very slow rate or when the rock being deformed is relatively weak. As folding occurs the units of rock bend forming anticlines, one way in which folding can occur in such a formation is by a small amount of subduction of one plate.
One continent may be overridden by the other but since the plate is far too light to sink it will uplift the overriding plate creating very large folds that deform the entire crust. Thrust faults are another form of deformation to occur in these areas. Faulting is generally the result of greater strain rates and stronger or more brittle rocks and these faults have a high angle and cause thickening by uplifting the rock onto itself. These types of faults are identified by the vertically repeating stratigraphy that they produce, during a collision when the strain reaches the breaking point of the rock a fracture will form in the rock. This fracture cuts across layers of rock to form a ramp which will allow movement to dissipate the accumulated strain, under compression the upper hanging wall rises and overrides the lower foot wall. The final type of deformation is crustal flow and this type of deformation is only able to occur when the crustal material is heated to a very high temperature, approximately 2/3 of its melting temperature
Geographic Names Information System
It is a type of gazetteer. GNIS was developed by the United States Geological Survey in cooperation with the United States Board on Geographic Names to promote the standardization of feature names, the database is part of a system that includes topographic map names and bibliographic references. The names of books and historic maps that confirm the feature or place name are cited, variant names, alternatives to official federal names for a feature, are recorded. Each feature receives a permanent, unique feature record identifier, sometimes called the GNIS identifier, the database never removes an entry, except in cases of obvious duplication. The GNIS accepts proposals for new or changed names for U. S. geographical features, the general public can make proposals at the GNIS web site and can review the justifications and supporters of the proposals. The Bureau of the Census defines Census Designated Places as a subset of locations in the National Geographic Names Database, U. S. Postal Service Publication 28 gives standards for addressing mail.
In this publication, the postal service defines two-letter state abbreviations, street identifiers such as boulevard and street, department of the Interior, U. S. Geological Survey, National Mapping Division, Digital Gazeteer, Users Manual. Least Heat Moon, Blue Highways, A Journey Into America, standard was withdrawn in September 2008, See Federal Register Notice, Vol.73, No. 170, page 51276 Report, Principles and Procedures, Domestic Geographic Names, U. S. Postal Service Publication 28, November 2000. Board on Geographic Names website Geographic Names Information System Proposals from the general public Meeting minutes
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
The Mesozoic Era is an interval of geological time from about 252 to 66 million years ago. This Era is called from a paleobotanist view the Age of Conifers, Mesozoic means middle life, deriving from the Greek prefix meso-/μεσο- for between and zōon/ζῷον meaning animal or living being. It is one of three eras of the Phanerozoic Eon, preceded by the Paleozoic and succeeded by the Cenozoic. The era is subdivided into three periods, the Triassic and Cretaceous, which are further subdivided into a number of epochs. The Mesozoic was a time of significant tectonic and evolutionary activity, the era witnessed the gradual rifting of the supercontinent Pangaea into separate landmasses that would eventually move into their current positions. The climate of the Mesozoic was varied, alternating between warming and cooling periods, however, the Earth was hotter than it is today. Birds first appeared in the Jurassic, having evolved from a branch of theropod dinosaurs, the first mammals appeared during the Mesozoic, but would remain small—less than 15 kg —until the Cenozoic.
Following the Paleozoic, the Mesozoic extended roughly 186 million years and this time frame is separated into three geologic periods. It is known as the Great Dying because it is considered the largest mass extinction in the Earths history, the upper boundary of the Mesozoic is set at the Cretaceous–Paleogene extinction event, which may have been caused by the impactor that created Chicxulub Crater on the Yucatán Peninsula. Towards the Late Cretaceous large volcanic eruptions are believed to have contributed to the Cretaceous–Paleogene extinction event. Approximately 50% of all genera became extinct, including all of the non-avian dinosaurs, the Triassic ranges roughly from 252 million to 201 million years ago. The Triassic is a time in Earths history bracketed between the Permian Extinction and the Triassic–Jurassic extinction event, two of the big five, and precedes the Jurassic Period and it has three major epochs, the Early Triassic, the Middle Triassic and the Late Triassic. The Early Triassic was between about 252 million to 247 million years ago and was dominated by deserts as Pangaea had not yet broken up, thus the interior was nothing, the Earth had just witnessed a massive die-off in which 95% of all life became extinct.
The most common life on earth were Lystrosaurus, labyrinthodonts. Temnospondyls evolved during this time and would be the dominant predator for much of the Triassic, the Middle Triassic spans roughly from 247 million to 237 million years ago. The Middle Triassic featured the beginnings of the breakup of Pangaea, the ecosystem had recovered from the devastation that was the Great Dying. Algae, sponge and crustaceans all had recovered, new aquatic reptiles evolved, such as ichthyosaurs and nothosaurs. Meanwhile, on land, pine forests flourished, as did groups of insects like mosquitoes, the first ancient crocodilians evolved, which sparked competition with the large amphibians that had since ruled the freshwater world
North American Cordillera
The North American Cordillera is the North American portion of the American Cordillera which is a mountain chain along the western side of the Americas. The North American Cordillera covers an area of mountain ranges, intermontane basins. It is called the Western Cordillera, the Western Cordillera of North America. This cordillera extends from the U. S. state of Alaska to the border of Mexico. The North American Cordillera includes some of the highest peaks on the continent and its mountain ranges generally run north to south along three main belts, the Pacific Coast Ranges in the west, the Nevadan belt in the middle, and the Laramide belt in the east. These three orogenic belts arose due to the engagement of tectonic plates which deformed the Earths lithosphere, for example, the Laramide orogeny changed the topography of the central Rocky Mountains and adjoining Laramide regions during the Late Cretaceous 80 million years ago. Prior to this time the Rocky Mountain region was occupied by a broad basin, further topographical evolution occurred during the Eocene and Oligocene, but since that time the deformation of the region has been relatively stable.
Generally speaking, it will be convenient here to consider these three belts going west to east, and north to south. In Alaska, south of the Interior Plains area, is the Rocky Mountain System, the Intermontane Basins and Ranges, in the Alaska panhandle, the mainland mountain ranges and offshore islands are extensions of respective ranges further south. In Canada, the North American Cordillera is usually divided into three regions, the western system, the interior system, and the eastern system. The western system includes the Coast Mountains, the system includes the Columbia Mountains. In Mexico, the Sierra Madre Occidental, and the Sierra Madre Oriental further east, to the west of the Sierra Madre Occidental, the Peninsular Ranges border the Pacific Ocean, and the Sierra Madre del Sur is the southern extension of the Peninsular Ranges. Sierra Madre means Mother Range in Spanish, the Nevadan belt runs up and down the middle of the North American Cordillera. Therefore, the areas of the cordillera can be divided up into the areas east of the Nevadan belt.
The Pacific Coast Ranges, comprising the Pacific Coast Belt, parallel the North American Pacific Coast, along the British Columbia and Alaska coast, the mountains intermix with the sea in a complex maze of fjords, with thousands of islands. Off the Southern California coast the Channel Islands archipelago of the Santa Monica Mountains extends for 160 miles, in southern Alaska, the primary mountain ranges are the Alaska Range, Wrangell Mountains, Saint Elias Mountains, Kenai Mountains, Chugach Mountains, and Talkeetna Mountains. The Yukon Ranges comprise the mountains in the part of the U. S. state of Alaska and most of the Yukon. This range has an area of 140,820 square miles, the Coast Mountains run from the lower Fraser River and the Fraser Canyon northwestward, separating the Interior Plateau from the Pacific Ocean
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