The topographic isolation of a summit is the minimum great-circle distance to a point of equal elevation, representing a radius of dominance in which the peak is the highest point. It can be calculated for small hills and islands as well as for major mountain peaks, can be calculated for submarine summits; the following sortable table lists the Earth's 40 most topographically isolated summits. The nearest peak to Germany's highest mountain, the 2,962-metre-high Zugspitze, that has a 2962-metre-contour is the Zwölferkogel in Austria's Stubai Alps; the distance between the Zugspitze and this contour is 25.8 km. Its isolation is thus 25.8 km. Because there are no higher mountains than Mount Everest, it has no definitive isolation. Many sources list its isolation as the circumference of the earth over the poles or – questionably, because there is no agreed definition – as half the earth's circumference. After Mount Everest, the highest mountain of the American continents, has the greatest isolation of all mountains.
There is no higher land for 16,534 kilometres when its height is first exceeded by Tirich Mir in the Hindu Kush. Mont Blanc is the highest mountain of the Alps; the geographically nearest higher mountains are all in the Caucasus. Kukurtlu, which rises near Mount Elbrus, is the reference peak for Mont Blanc. Musala is the highest peak in Rila mountain, in Bulgaria and the Balkan Peninsula, standing at 2,925 m it is the 4th most topographically isolated peak in Continental Europe.. Rila is the 6th highest mountain in Europe. With a topographic prominence of 2473 m, Musala is the 6th highest peak by topographic prominence in mainland Europe. Table of the most isolated major summits of North America Table of the most isolated major summits of the United States Most isolated mountain peaks of Canada Most isolated mountain peaks of Mexico geodesy physical geography summit topographic elevation topographic prominence topography bivouac.com Canadian Mountain Encyclopedia peakbagger.com peaklist.org peakware.com World Mountain Encyclopedia summitpost.org^ ^ "Europe Ultra-Prominences".
Peaklist. Retrieved 26 February 2015
Cuyamaca Rancho State Park
Cuyamaca Rancho State Park is a state park in California, United States, located 40 miles east of San Diego in the Cuyamaca and Laguna Mountains of the Peninsular Ranges. The park's 26,000 acres feature pine and oak forests, with meadows and streams that exist due to the high elevation of the area compared to its surroundings; the park includes the second-highest point in San Diego County. Park amenities include trails for hiking, horseback riding, mountain biking, as well as campgrounds for family, group and primitive trail camping. Wildlife in the area includes mountain lions, which have been known to attack humans, park literature emphasizes avoiding encounters with them. Numerous other species of mammals, birds and amphibians are known to reside within the park; the park was closed for several months due to massive damage incurred in the 2003 Cedar Fire. Although much of the forest was burned, the park has since been reopened and the fire ecology regenerating native plants are re-growing and returning.
Cuyamaca Rancho State Park is located in the Peninsular Range, which extends from the San Jacinto Mountains north of the park, southward to the tip of Baja California. At the western edge of the most seismically active area in North America, the range is a great uplifted plateau, cut off from the Colorado Desert to the east by the Elsinore Fault Zone, where vertical movement over the last two million years has amounted to thousands of feet of tectonic uplift. Metamorphosed sediments such as schist and quartzite are abundant in the Cuyamacas in the Stonewall Mine area. Most of the rocks now seen in the park are plutonic: either the granodiorite comprising Stonewall Peak, or the gabbro comprising Cuyamaca Peak; as these bedrocks weather, they become the parent material of the coarse, red soil found throughout the area. Gabbro weathers to a darker red soil than other quartz-rich rock. Gold is a natural element that appears around granite formations because gold forms during cooling and solidification of igneous rock.
Gold occurs in association with quartz, either as pure gold or as an ore. In the Cuyamaca area, gold is associated with the metasediment called Julian Schist. At mines in this area, including the Stonewall, veins of gold were followed into the bedrock and the surrounding ore excavated. Most streams in the park have small amounts of gold, since it is being removed from the quartz exposures by weathering. Cuyamaca's average elevation of nearly 5,000 feet enables many conifers and broadleaf trees to exist; the conifers include the white fir, incense cedar, Coulter pine, Jeffrey pine, sugar pine and ponderosa pine. The broadleaves include the white alder, Arizona ash, California sycamore, Fremont cottonwood, coast live oak, canyon live oak, Engelmann oak, California black oak, interior live oak, oracle oak, red willow. Large shrubs, those ranging from 4–15 feet, include chamise, Eastwood manzanita, Cuyamaca manzanita, Mexican manzanita, cupleaf mountain lilac, whitebark mountain lilac, Palmer mountain lilac, mountain mahogany, creek dogwood, Parish goldenbush, yerba santa, Parish burning bush, California barberry, laurel sumac, hollyleaf cherry, western chokecherry, scrub oak, western azalea, white sage, elderberry.
The park's smaller shrubs, ranging from 1–4 feet, include California buckwheat, Wright's buckwheat, chaparral honeysuckle, California rose, creeping sage and poison oak. Seen mammals in Cuyamaca Rancho State Park include the southern mule deer, California ground squirrel, Merriam's chipmunk, black-tailed jackrabbit, brush rabbit, Audubon's cottontail rabbit. Cougars are present but seen. About 200 species of birds have been documented in the park. Several of the most seen bird residents and migrants are the wild turkey, acorn woodpecker, Nuttall's woodpecker, northern flicker, Steller's jay, western bluebird, white-breasted nuthatch, mountain chickadee, oak titmouse, American robin, red-tailed hawk, red-shouldered hawk. Migrants and summer residents include the black-headed grosbeak, Baltimore oriole, ash-throated flycatcher, western wood pewee, house wren, several warblers, the lesser goldfinch. Resident amphibians and reptiles include the canyon tree frog, Pacific tree frog, red-legged frog, western toad, common king snake, gopher snake, California mountain kingsnake, striped racer, western garter snake.
Cougars are quite elusive, but for a ten-year span Cuyamaca Rancho State Park experienced a rash of incidents between visitors and cougars, including one human fatality. Park users are warned not to hike, horseback ride or bike alone. Cuyamaca Rancho's first reported cougar incident took place in June 1988. A European couple with a small child was chased by two cougars in the park's Green Valley Campground. A game warden killed the two male cats. In September 1993 a cougar chased two horseback riders for.5 miles, prompting park officials to close Cuyamaca Rancho for two weeks and install gated barriers around the campgrounds and parking areas. 11 days after the park reopened, however, a different cougar nipped a girl playing with her family in the campground and fought with their dog. The 41-pound juvenile female cat was located and shot.1994 saw two separate incidents in which a cougar acted aggressively toward a party of three humans. In December 56-year-old Iris Kenna was killed during an early morning solo hike by a 130-pound male cougar, which was
Julian is a census-designated place in San Diego County, California, in the United States. As of the 2010 census, the population was 1,502, down from 1,621 at the 2000 census. Julian is an official California Historical Landmark; the Julian townsite and surrounding area is defined by the San Diego County Zoning Ordinance Section 5749 as the Julian Historic District. This designation requires that development adhere to certain guidelines that are administered by the Architectural Review Board of the Julian Historic District, appointed by the San Diego County Board of Supervisors; the town is known for its apple pie and its annual Julian Apple Days Festival, which began in 1949. The first European settlers to arrive in this area were "Cockney Bill" Williams from England and John Wesley Horrell, who both arrived in the area in 1850 or 1851; the town itself was first settled by Drury, J. O. Bailey, all brothers, they were passing through the region from San Bernardino en route to Arizona in 1869, in the wake of the American Civil War.
Taken to the beauty of the Julian area, Drury Bailey interrupted the group’s travel plans and chose instead to settle here. Julian was a former Confederate soldier, elected San Diego County Assessor. Shortly afterwards gold was discovered in the Julian region. A tent city formed in the boomtown, followed by more permanent structures as it became apparent that gold mining in Julian would persist for some time. Victorian-style structures were constructed in the latest-stage of Julian’s early settlement, including the Hoskins House. After the American Civil War, in 1869, A. E. "Fred" Coleman, a former slave, crossed over what is now known as Coleman Creek just west of Julian. Seeing a glint of gold in the stream bed, he climbed down from his horse to investigate. Having had previous experience in the gold fields, he retrieved his frying pan and began panning the sands of the creek. Soon thereafter Coleman established the Coleman Mining District and was its recorder and began the mining camp called Emily City renamed Coleman City.
Learning of the find, others tried to trace the gold to its source. On February 22, 1870, the first "lode", or hard rock, mining claim was filed in the Julian area. Since February 22 was President George Washington's birthday, the mine was named the Washington mine. Soon hundreds of anxious men and families rushed to Julian to stake their claims. Julian became a tent city overnight. In April 1870, the area's first sawmill was set up and Julian began to take on a more permanent structure. Attempts to build rival mining towns at Coleman City, Branson City and Eastwood were defeated. Owners of the Cuyamaca rancho Land Grant claimed Julian, its mines were within the Rancho boundaries. In 1873, the courts ruled that the Rancho did not include the mines. While the miners tried to wrestle the gold from deep within the earth, James Madison brought a wagon load of young apple trees into the mountains; the fruit trees flourished in the fresh air. Apples are still a big product in Julian, many of which are used for making the world-famous Julian apple pies.
Local historians have variably suggested that the Julian of 1873 rivaled San Diego in population and they unsuccessfully attempted to shift the county seat to the city. According to a bronze historical plaque appearing in the town, in the early days of Julian, the majority of San Diego County's black population resided in or near the town, including the founders of the Robinson Hotel and a noted resident, America Newton, a freed slave who laundered miners' clothing. Of the 55 blacks living in San Diego County during the 1880 census, 33 lived in the Julian area. In 1976, Julian approved a plan that required the exteriors of any buildings on Main Street to be no younger in age than 1913. Many structures bear a Victorian architecture. In the 1970s, as many of 25,000 visitors visited the settlement per annum. Julian had five wells in the 1970s. A county planner surveyed the water capacity for Julian and indicated that it was unlikely that Julian would have enough inexpensive water to sustain large-scale development.
During a period of drought, the community of Julian was compelled by the San Diego County supervisors to obey a moratorium on development until a 30,000 gallon waste treatment plant could reduce the risk that a developing Julian’s sewage output might pollute the San Diego River. Julian’s water supply became dependent on a single well owned by a local property owner named Jerry Zweig, as the community’s water board-owned resources were depleted in a drought in the 1990s and were limited by contamination as a defunct Chevron station contaminated three of the eight publicly-owned water wells into the late 1980s. On Memorial Day in 1989, two individuals and Gustav Oran Hudson disputed a claim to land to the Ready Relief and Hubbard Mines in Julian’s Chariot Canyon over rights to an area where both had intentions to prospect for gold. Hudson and his family arrived at the property at a time when Haimes’ appointed caretaker and the caretaker’s friend of Julian; the resulting escalation involved the replacement of a padlock at the Hubbard Mine by the Hudsons, co
In topography, prominence measures the height of a mountain or hill's summit relative to the lowest contour line encircling it but containing no higher summit within it. It is a measure of the independence of a summit. A peak's key col is a unique point on this contour line and the parent peak is some higher mountain, selected according to various objective criteria. There are at least two definitions of prominence: The prominence of a peak is the minimum height necessary to descend to get from the summit to any higher terrain, which can be calculated for a given peak in the following way: for every path connecting the peak to higher terrain, find the lowest point on the path. See Figure 1; the prominence of a peak is the height of the peak’s summit above the lowest contour line encircling it but containing no higher summit within it. This allows the prominence of points like Everest to be calculated, as long as a lowest point can be defined; the following mental exercise may illustrate the meaning of topographic prominence.
Imagine a peak and imagine that an imaginary sea level rises to the peak. Now lower the imaginary sea level and an imaginary island appears beneath your feet; the island will merge with other islands that emerge. The island will touch an island with a higher peak than the initial island The summit of that island is the parent peak of the summit, the point at which the two islands touch is the key col of the summit, the elevation rise from the key col to the summit is the topographic prominence of the summit; the parent peak may be either far from the subject peak. The summit of Mount Everest is the parent peak of Aconcagua at a distance of 17,755 km, as well as the parent of the South Summit of Mount Everest at a distance of 360 m; the key col may be close to the subject peak or far from it. The key col for Aconcagua, if sea level is disregarded, is the Bering Strait at a distance of 13,655 km; the key col for the South Summit of Mount Everest is about 100 m distant. Prominence is interesting to many mountaineers because it is an objective measurement, correlated with the subjective significance of a summit.
Peaks with low prominence are either subsidiary tops of some higher summit or insignificant independent summits. Peaks with high prominence tend to be the highest points around and are to have extraordinary views. Only summits with a sufficient degree of prominence are regarded as independent mountains. For example, the world's second-highest mountain is K2. While Mount Everest's South Summit is taller than K2, it is not considered an independent mountain because it is a sub-summit of the main summit. Many lists of mountains take topographic prominence as cutoff. John and Anne Nuttall's The Mountains of England and Wales uses a cutoff of 15 m, Alan Dawson's list of Marilyns uses 150 m.. In the contiguous United States, the famous list of "fourteeners" uses a cutoff of 300 ft / 91 m. In the U. S. 2000 ft of prominence has become an informal threshold that signifies that a peak has major stature. Lists with a high topographic prominence cutoff tend to favor isolated peaks or those that are the highest point of their massif.
While the use of prominence as a cutoff to form a list of peaks ranked by elevation is standard and is the most common use of the concept, it is possible to use prominence as a mountain measure in itself. This generates lists of peaks ranked by prominence, which are qualitatively different from lists ranked by elevation; such lists tend to emphasize isolated high peaks, such as range or island high points and stratovolcanoes. One advantage of a prominence-ranked list is that it needs no cutoff since a peak with high prominence is automatically an independent peak, it is common to define a peak's parent as a particular peak in the higher terrain connected to the peak by the key col. If there are many higher peaks there are various ways of defining which one is the parent, not based on geological or geomorphological factors; the "parent" relationship defines a hierarchy. For example, in Figure 1, the middle peak is a subpeak of the right peak, in turn a subpeak of the left peak, the highest point on its landmass.
In that example, there is no controversy over the hierarchy. These different definitions follow. A special case occurs for the highest point on an oceanic continent; some sources define no parent in this case. Called prominence island parentage, this is defined as follows. In figure 2 the key col of peak A is at the meeting place of two closed contours, one encircling A and the other containing at least one higher peak; the encirclement parent of A is the highest peak, inside this other contour. In terms of the
Geographic coordinate system
A geographic coordinate system is a coordinate system that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are chosen such that one of the numbers represents a vertical position and two or three of the numbers represent a horizontal position. A common choice of coordinates is latitude and elevation. To specify a location on a plane requires a map projection; the invention of a geographic coordinate system is credited to Eratosthenes of Cyrene, who composed his now-lost Geography at the Library of Alexandria in the 3rd century BC. A century Hipparchus of Nicaea improved on this system by determining latitude from stellar measurements rather than solar altitude and determining longitude by timings of lunar eclipses, rather than dead reckoning. In the 1st or 2nd century, Marinus of Tyre compiled an extensive gazetteer and mathematically-plotted world map using coordinates measured east from a prime meridian at the westernmost known land, designated the Fortunate Isles, off the coast of western Africa around the Canary or Cape Verde Islands, measured north or south of the island of Rhodes off Asia Minor.
Ptolemy credited him with the full adoption of longitude and latitude, rather than measuring latitude in terms of the length of the midsummer day. Ptolemy's 2nd-century Geography used the same prime meridian but measured latitude from the Equator instead. After their work was translated into Arabic in the 9th century, Al-Khwārizmī's Book of the Description of the Earth corrected Marinus' and Ptolemy's errors regarding the length of the Mediterranean Sea, causing medieval Arabic cartography to use a prime meridian around 10° east of Ptolemy's line. Mathematical cartography resumed in Europe following Maximus Planudes' recovery of Ptolemy's text a little before 1300. In 1884, the United States hosted the International Meridian Conference, attended by representatives from twenty-five nations. Twenty-two of them agreed to adopt the longitude of the Royal Observatory in Greenwich, England as the zero-reference line; the Dominican Republic voted against the motion, while Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911.
In order to be unambiguous about the direction of "vertical" and the "horizontal" surface above which they are measuring, map-makers choose a reference ellipsoid with a given origin and orientation that best fits their need for the area they are mapping. They choose the most appropriate mapping of the spherical coordinate system onto that ellipsoid, called a terrestrial reference system or geodetic datum. Datums may be global, meaning that they represent the whole Earth, or they may be local, meaning that they represent an ellipsoid best-fit to only a portion of the Earth. Points on the Earth's surface move relative to each other due to continental plate motion and diurnal Earth tidal movement caused by the Moon and the Sun; this daily movement can be as much as a metre. Continental movement can be up to 10 m in a century. A weather system high-pressure area can cause a sinking of 5 mm. Scandinavia is rising by 1 cm a year as a result of the melting of the ice sheets of the last ice age, but neighbouring Scotland is rising by only 0.2 cm.
These changes are insignificant if a local datum is used, but are statistically significant if a global datum is used. Examples of global datums include World Geodetic System, the default datum used for the Global Positioning System, the International Terrestrial Reference Frame, used for estimating continental drift and crustal deformation; the distance to Earth's center can be used both for deep positions and for positions in space. Local datums chosen by a national cartographical organisation include the North American Datum, the European ED50, the British OSGB36. Given a location, the datum provides the latitude ϕ and longitude λ. In the United Kingdom there are three common latitude and height systems in use. WGS 84 differs at Greenwich from the one used on published maps OSGB36 by 112 m; the military system ED50, used by NATO, differs from about 120 m to 180 m. The latitude and longitude on a map made against a local datum may not be the same as one obtained from a GPS receiver. Coordinates from the mapping system can sometimes be changed into another datum using a simple translation.
For example, to convert from ETRF89 to the Irish Grid add 49 metres to the east, subtract 23.4 metres from the north. More one datum is changed into any other datum using a process called Helmert transformations; this involves converting the spherical coordinates into Cartesian coordinates and applying a seven parameter transformation, converting back. In popular GIS software, data projected in latitude/longitude is represented as a Geographic Coordinate System. For example, data in latitude/longitude if the datum is the North American Datum of 1983 is denoted by'GCS North American 1983'; the "latitude" of a point on Earth's surface is the angle between the equatorial plane and the straight line that passes through that point and through the center of the Earth. Lines joining points of the same latitude trace circles on the surface of Earth called parallels, as they are parallel to the Equator and to each other; the North Pole is 90° N. The 0° parallel of latitude is designated the Equator, the fun
The United States of America known as the United States or America, is a country composed of 50 states, a federal district, five major self-governing territories, various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U. S. is the third most populous country. The capital is Washington, D. C. and the largest city by population is New York City. Forty-eight states and the capital's federal district are contiguous in North America between Canada and Mexico; the State of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The State of Hawaii is an archipelago in the mid-Pacific Ocean; the U. S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The diverse geography and wildlife of the United States make it one of the world's 17 megadiverse countries.
Paleo-Indians migrated from Siberia to the North American mainland at least 12,000 years ago. European colonization began in the 16th century; the United States emerged from the thirteen British colonies established along the East Coast. Numerous disputes between Great Britain and the colonies following the French and Indian War led to the American Revolution, which began in 1775, the subsequent Declaration of Independence in 1776; the war ended in 1783 with the United States becoming the first country to gain independence from a European power. The current constitution was adopted in 1788, with the first ten amendments, collectively named the Bill of Rights, being ratified in 1791 to guarantee many fundamental civil liberties; the United States embarked on a vigorous expansion across North America throughout the 19th century, acquiring new territories, displacing Native American tribes, admitting new states until it spanned the continent by 1848. During the second half of the 19th century, the Civil War led to the abolition of slavery.
By the end of the century, the United States had extended into the Pacific Ocean, its economy, driven in large part by the Industrial Revolution, began to soar. The Spanish–American War and World War I confirmed the country's status as a global military power; the United States emerged from World War II as a global superpower, the first country to develop nuclear weapons, the only country to use them in warfare, a permanent member of the United Nations Security Council. Sweeping civil rights legislation, notably the Civil Rights Act of 1964, the Voting Rights Act of 1965 and the Fair Housing Act of 1968, outlawed discrimination based on race or color. During the Cold War, the United States and the Soviet Union competed in the Space Race, culminating with the 1969 U. S. Moon landing; the end of the Cold War and the collapse of the Soviet Union in 1991 left the United States as the world's sole superpower. The United States is the world's oldest surviving federation, it is a representative democracy.
The United States is a founding member of the United Nations, World Bank, International Monetary Fund, Organization of American States, other international organizations. The United States is a developed country, with the world's largest economy by nominal GDP and second-largest economy by PPP, accounting for a quarter of global GDP; the U. S. economy is post-industrial, characterized by the dominance of services and knowledge-based activities, although the manufacturing sector remains the second-largest in the world. The United States is the world's largest importer and the second largest exporter of goods, by value. Although its population is only 4.3% of the world total, the U. S. holds 31% of the total wealth in the world, the largest share of global wealth concentrated in a single country. Despite wide income and wealth disparities, the United States continues to rank high in measures of socioeconomic performance, including average wage, human development, per capita GDP, worker productivity.
The United States is the foremost military power in the world, making up a third of global military spending, is a leading political and scientific force internationally. In 1507, the German cartographer Martin Waldseemüller produced a world map on which he named the lands of the Western Hemisphere America in honor of the Italian explorer and cartographer Amerigo Vespucci; the first documentary evidence of the phrase "United States of America" is from a letter dated January 2, 1776, written by Stephen Moylan, Esq. to George Washington's aide-de-camp and Muster-Master General of the Continental Army, Lt. Col. Joseph Reed. Moylan expressed his wish to go "with full and ample powers from the United States of America to Spain" to seek assistance in the revolutionary war effort; the first known publication of the phrase "United States of America" was in an anonymous essay in The Virginia Gazette newspaper in Williamsburg, Virginia, on April 6, 1776. The second draft of the Articles of Confederation, prepared by John Dickinson and completed by June 17, 1776, at the latest, declared "The name of this Confederation shall be the'United States of America'".
The final version of the Articles sent to the states for ratification in late 1777 contains the sentence "The Stile of this Confederacy shall be'The United States of America'". In June 1776, Thomas Jefferson wrote the phrase "UNITED STATES OF AMERICA" in all capitalized letters in the headline of his "original Rough draught" of the Declaration of Independence; this draft of the document did not surface unti
San Diego County, California
San Diego County the County of San Diego, is a county in the southwestern corner of the state of California, in the United States. As of the 2010 census, the population was 3,095,313. Making it California's second-most populous county and the fifth-most populous in the United States, its county seat is the eighth-most populous city in the United States. It is the southwesternmost county in the 48 contiguous United States. San Diego County comprises the San Diego-Carlsbad, CA Metropolitan Statistical Area, the 17th most populous metropolitan statistical area and the 18th most populous primary statistical area of the United States as of July 1, 2012. San Diego is part of the San Diego–Tijuana metropolitan area, the largest metropolitan area shared between the United States and Mexico. Greater San Diego ranks as the 38th largest metropolitan area in the Americas. San Diego County has more than 70 miles of coastline; this forms the most densely populated region of the county, which has a mild Mediterranean to semiarid climate and extensive chaparral vegetation, similar to the rest of the western portion of southern California.
Precipitation and temperature extremes increase to the east, with mountains that receive frost and snow in the winter. These lushly forested mountains receive more rainfall than average in southern California, while the desert region of the county lies in a rain shadow to the east, which extends into the Desert Southwest region of North America. There are 16 naval and military installations of the U. S. Navy, U. S. Marine Corps, the U. S. Coast Guard in San Diego County; these include the Naval Base San Diego, Marine Corps Base Camp Pendleton, Marine Corps Air Station Miramar, Naval Air Station North Island. From north to south, San Diego County extends from the southern borders of Orange and Riverside Counties to the Mexico-U. S. Border and Baja California. From west to east, San Diego County stretches from the Pacific Ocean to its boundary with Imperial County; the area, now San Diego County has been inhabited for more than 12,000 years by Kumeyaay, Luiseño, Cupeño and Cahuilla Indians and their local predecessors.
In 1542, the explorer Juan Rodríguez Cabrillo, who may have been born in Portugal but sailed on behalf of Spain, claimed San Diego Bay for the Spanish Empire, he named the site San Miguel. In November 1602, Sebastián Vizcaíno surveyed the harbor and what are now Mission Bay and Point Loma and named the area for Saint Didacus, a Spaniard more known as San Diego. European settlement in what is now San Diego County began with the founding of the San Diego Presidio and Mission San Diego de Alcalá by Spanish soldiers and clerics in 1769; this county was part of Alta California under the Viceroyalty of New Spain until the Mexican declaration of independence. From 1821 through 1848 this area was part of Mexico. San Diego County became part of the United States as a result of the Treaty of Guadalupe Hidalgo in 1848, ending the Mexican–American War; this treaty designated the new border as terminating at a point on the Pacific Ocean coast which would result in the border passing one Spanish league south of the southernmost portion of San Diego Bay, thus ensuring that the United States received all of this natural harbor.
San Diego County was one of the original counties of California, created at the time of California statehood in 1850. At the time of its establishment in 1850, San Diego County was large, included all of southernmost California south and east of Los Angeles County, it included areas of what are now Inyo and San Bernardino Counties, as well as all of what are now Riverside and Imperial Counties. During the part of the 19th century, there were numerous changes in the boundaries of San Diego County, when various areas were separated to make up the counties mentioned above; the most recent changes were the establishments of Riverside County in 1893 and Imperial County in 1907. Imperial County was the last county to be established in California, after this division, San Diego no longer extended from the Pacific Ocean to the Colorado River, it no longer covered the entire border between California and Mexico. According to the U. S. Census Bureau, the county has an area of 4,526 square miles, of which 4,207 square miles is land and 319 square miles is water.
The county is larger in area than the combined states of Rhode Delaware. San Diego County has a varied topography. On its western side is more than 70 miles of coastline. Most of San Diego between the coast and the Laguna Mountains consists of hills and small canyons. Snow-capped mountains rise with the Sonoran Desert farther to the east. Cleveland National Forest is spread across the central portion of the county, while the Anza-Borrego Desert State Park occupies most of the northeast. Although the county's western third is urban, the mountains and deserts in the eastern two-thirds are undeveloped backcountry. Most of these backcountry areas are home to a native plant community known as chaparral. San Diego County contains more than a million acres of chaparral, twice as much as any other California county. North San Diego County is known as North County; the eastern suburbs are collectively known as East County, though most still lie in the western third of the county. The southern suburbs and southern detached portion of the city of San Diego, extending to the Mexican border, are collectively referred to as South Bay.
Periodically the area has been subject to wildfires th