Baja California Peninsula
The Baja California Peninsula is a peninsula in Northwestern Mexico. It separates the Pacific Ocean from the Gulf of California; the peninsula extends 1,247 km from Mexicali, Baja California in the north to Cabo San Lucas, Baja California Sur in the south. It ranges from 40 km at its narrowest to 320 km at its widest point and has 3,000 km of coastline and 65 islands; the total area of the Baja California Peninsula is 143,390 km2. The peninsula is separated from mainland Mexico by the Gulf of the Colorado River. There are four main desert areas on the peninsula: the San Felipe Desert, the Central Coast Desert, the Vizcaíno Desert and the Magdalena Plain Desert; the land of California existed as a myth among European explorers. The earliest known mention of the idea of California was in the 1510 romance novel Las Sergas de Esplandián by Spanish author Garci Rodríguez de Montalvo; the book described the Island of California as being west of the Indies, "very close to the side of the Terrestrial Paradise.
Following Hernán Cortés' conquest of Mexico, the lure of an earthly paradise as well as the search for the fabled Strait of Anián, helped motivate him to send several expeditions to the west coast of New Spain in the 1530s and early 1540s. Its first expedition reached the Gulf of California and California, proved the Island of California was in fact a peninsula; the idea of the island persisted for well over a century and was included in many maps. The Spaniards gave the name Las Californias to the peninsula and lands to the north, including both Baja California and Alta California, the region that became parts of the present-day U. S. states of California, Utah and parts of Colorado and Wyoming. 1532: Hernán Cortés sends three ships north along the coast of Mexico in search of the Island of California. The three ships disappear without a trace. 1533: Cortés sends a follow-up mission to search for the lost ships. Pilot Fortún Ximénez leads a mutiny and founds a settlement in the Bay of La Paz before being killed.
1539: Francisco de Ulloa explores both coasts. 1622: A map by Michiel Colijn of Amsterdam showed California as a peninsula rather than an island. Previous maps show the Gulf terminating in its correct location. 1690s–1800s: Spanish settlement and colonization in lower Las Californias, the first Spanish missions in Baja California are established by Jesuit missionaries. 1701: Explorations by Eusebio Kino expanded knowledge of the Gulf of California coast. Kino did not believe. 1767: Jesuits expelled. 1769: Franciscans go with the Portola expedition to establish new missions in Alta California. Control of the existing Baja missions passes to the Dominican Order. 1773: Francisco Palóu's line demarcates Franciscan and Dominican areas of mission control. 1804: Las Californias divided into Alta and Baja California, using Palóu's line. 1810–1821: Mexican War of Independence 1821: First Mexican Empire, Baja California Territory established, covering Baja California Peninsula. 1847: The Battle of La Paz and the Siege of La Paz occurs, as well as several other engagements.
1848: Treaty of Guadalupe Hidalgo cedes Alta California to the United States. As a U. S. territory it receives the California Gold Rush, causing increased maritime traffic along the peninsula. 1850: California admitted to U. S. statehood. 1853: William Walker, with 45 men, captures the capital city of La Paz and declares himself President of the Republic of Lower California. Mexico forces him to retreat a few months later. 1930–31: The Territory of Baja California is further divided into Northern and Southern territories. 1952: The North Territory of Baja California becomes the 29th State of Mexico, Baja California. The southern portion, below 28°N, remains a federally administered territory. 1973: The 1,700 km long Trans-Peninsular Highway, is finished. It is the first paved road; the highway was built by the Mexican government to improve Baja California's economy and increase tourism. 1974: The South Territory of Baja California becomes the 31st state, Baja California Sur. The province of the Californias was united until 1804, in the Spanish colonial Viceroyalty of New Spain, when it was divided into Alta and Baja California.
The two Californias division was kept after Mexican independence in 1821. The Spanish Baja California Province became Mexican Baja California Territory, remained a separate territory until 1836. In 1836, the Siete Leyes constitutional reforms reunited both Californias in the Departamento de las Californias. After 1848, the Baja California Peninsula again became a Mexican territory when Alta California was ceded to the United States. In 1931 Baja California Territory was divided into southern territories. In 1952, the "North Territory of Baja California" became the 29th State of Mexico as Baja California. In 1974, the "South Territory of Baja California" became the 31st state as Baja California Sur; the northern part is the state of Baja California. The citizens of Baja California are named bajacalifornianos. Mexicali is the capital; the southern part, below 28° north, is the state of Baja California Sur. The citizens of Baja California Sur are named sudcalifornianos. La Paz is its capital
The Oregon Zoo the Portland Zoo and the Washington Park Zoo, is a zoo located in Washington Park, Oregon 2 miles southwest of downtown Portland. Founded in 1888, it is the oldest zoo west of the Mississippi River; the 64-acre zoo is owned by the regional Metro government. It holds more than 1,800 animals of more than 230 species, including 19 endangered species and 9 threatened species; the zoo boasts an extensive plant collection throughout its animal exhibits and specialized gardens. The zoo operates and maintains the 2 ft 6 in narrow gauge Washington Park & Zoo Railway that connected to the International Rose Test Garden inside the park, but runs only within the zoo; the Oregon Zoo is Oregon's largest paid and arguably most popular visitor attraction, with more than 1.6 million visitors in 2016. The zoo is a member of the Association of Aquariums; the Oregon Zoo was founded in 1888. It all began with two bears purchased by Richard Knight -- one grizzly. A former seaman turned pharmacist, Knight began collecting animals from his seafaring friends.
He kept his collection in the back of his drug store on Morrison streets. When caring for the animals became too large a responsibility he sought to sell them to the city of Portland. Instead of buying the animals, the city offered to give Knight two circus cages and allowed him to place the caged bears on the grounds of City Park. Care and feeding of the bears, still fell to the Knight family and friends, it wasn't long. Just five months he offered to donate the bears, along with their cages, to the city. Portland City Council accepted his offer on November 7, 1888, thus began the Portland Zoo. Located in Washington Park, it was sometimes referred to as the Washington Park Zoo. By 1894, there were over 300 animals in the zoo’s collection. In 1925, the zoo moved to the site of the present Portland Japanese Garden, still within Washington Park; the zoo moved again in 1958 -- 59 to its current site, designed by Tucker & Wallmann. This was located in Hoyt Park, west of Washington Park, but some years the two parks were combined as Washington Park.
At this time, the Portland Zoo Railway was constructed to connect the zoo to its former site in Washington Park and other attractions there. The zoo's move to the new, much larger site was made in stages, over more than a year, with the first animals being moved in spring 1958 and limited public access being opened in June 1958, one day after the first section of the Zoo Railway opened. During the transition period the new zoo was only open on weekends, as most animals were still at the old site awaiting completion of their new enclosures. However, the new railway operated six days a week until mid-September. Meanwhile, the old zoo remained in operation, but in May 1959 was restricted to pedestrian access only, closed to automobile access, for its last months of operation; the zoo at its current site opened on July 3, 1959. It was renamed the Portland Zoological Gardens at that time, but remained known as the Portland Zoo; the elephants and big cats were not moved to the new zoo until November.
A new interchange was constructed on the adjacent freeway, the Sunset Highway, for better access to the new zoo. The zoo became popular locally in 1953; the zoo became world-famous in 1962. He was the first elephant born in the Western Hemisphere in 44 years and was the tallest Asian elephant in the United States at 10.5 ft tall. A total of 28 more calves have been born at the Oregon Zoo, including seven sired by Packy, making it the most successful zoo elephant breeding program in the world. On August 23, 2008, Rose-Tu, the granddaughter of the zoo's first elephant Rosy, gave birth to a son named Samudra; the birth made Samudra the first third-generation captive-born elephant in North America. Attendance in 1962, the year in which Packy was born, was 1.2 million people. Over the next several years, the number of animals declined, from 450 in 1962 to 386 in 1976, annual attendance declining over the same period, reaching its lowest point in 1975, with 448,198 visitors; until 1971, the zoo was operated by the City, by the Portland Zoological Society under contract to the City.
In 1976, area voters approved a tax levy plan under which the zoo was taken over by the Metropolitan Service District. Ownership of the zoo passed to Metro on July 1, 1976. Metro has continued expansion projects, aided by donors and volunteers. In 1976, MSD renamed the zoo the Washington Park Zoo after a naming contest; the railway was renamed the Washington Zoo Railway two years later. The decline in attendance seen in the 1960s and 1970s began to reverse, the zoo recorded 752,632 visitors in 1984 and 897,189 in 1986; the Metro Council changed the zoo's name from the Washington Park Zoo to the Oregon Zoo in April 1998. In September of that year, the zoo became accessible by the region's MAX light rail system, with the opening of a Westside MAX line featuring an underground Washington Park station. In 2003, the zoo began participation in a California condor recovery program started by San Diego Wild Animal Park and Los Angeles Zoo; the program is designed to breed California condors to be released into the wild and save them from extinction.
In November 2008, regional voters approved a $125 million bond measu
A drainage divide, water divide, ridgeline, water parting or height of land is elevated terrain that separates neighbouring drainage basins. On rugged land, the divide lies along topographical ridges, may be in the form of a single range of hills or mountains, known as a dividing range. On flat terrain where the ground is marshy, the divide may be harder to discern. A triple divide is a point a summit, where two drainage divides intersect. A valley floor divide is a low drainage divide that runs across a valley, sometimes created by deposition or stream capture. Major divides separating rivers that drain to different seas or oceans are called continental divides; the term height of land is a phrase used in Canada and the United States to refer to the divide between two drainage basins. Height of land is used in border descriptions, which are set according to the "doctrine of natural boundaries". In glaciated areas it refers to a low point on a divide where it is possible to portage a canoe from one river system to another.
Drainage divides can be divided into three types: Continental divide in which waters on each side flow to different oceans, such as the Congo-Nile Divide. Every continent except Antarctica has one or more continental divides. Major drainage divide in which waters on each side of the divide never meet but flow into the same ocean, such as the divide between the Yellow River basin and the Yangtze. Another, more subtle, example is the Schuylkill-Lehigh divide at Pisgah Mountain in Pennsylvania in which two minor creeks divide to flow and grow east and west joining the Lehigh River and Delaware River or the Susquehanna River and Potomac River, with each tributary complex having separate outlets into the Atlantic. Minor drainage divide in which waters part but rejoin at a river confluence, such as the Mississippi River and the Missouri River drainage divides. A valley-floor divide occurs on the bottom of a valley and arises as a result of subsequent depositions, such as scree, in a valley through which a river flowed continuously.
Examples include the Kartitsch Saddle in the Gail valley in East Tyrol, which forms the watershed between the Drau and the Gail, the divides in the Toblacher Feld between Innichen and Toblach in Italy, where the Drau empties into the Black Sea and the Rienz into the Adriatic. Settlements are built on valley-floor divides in the Alps. Examples are Eben im Kirchberg in Tirol and Waidring. Low divides with heights of less than two metres are found on the North German Plain within the Urstromtäler, for example, between Havel and Finow in the Eberswalde Urstromtal. In marsh deltas such as the Okavango, the largest drainage area on earth, or in large lakes areas, such as the Finnish Lakeland, it is difficult to find a meaningful definition of a watershed. Another case is bifurcation, where the watershed is in the river bed, a wetland or underground; the largest watershed of this type is the bifurcation of the Orinoco in the north of South America, whose main stream empties into the Caribbean, but which drains into the South Atlantic via the Casiquiare canal and Amazon River.
Since ridgelines are sometimes easy to see and agree about, drainage divides may form natural borders defining political boundaries, as with the Royal Proclamation of 1763 in British North America which coincided with the ridgeline of the Appalachian Mountains forming the Eastern Continental Divide that separated settled colonial lands in the east from Indian Territory to the west. Drainage divides hinder waterway navigation. In pre-industrial times, water divides were crossed at portages. Canals connected adjoining drainage basins. Important examples are the Chicago Portage, connecting the Great Lakes and Mississippi by the Chicago Sanitary and Ship Canal, the Canal des Deux Mers in France, connecting the Atlantic and the Mediterranean; the name is enshrined at the Height of Land Portage which joins the Great Lakes to the rivers of western Canada. List of watershed topics River source – The starting point of a riverCategories: Category:Drainage basins
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
Sierra de Juárez
The Sierra de Juárez known as the Sierra Juarez, is a mountain range located in Tecate Municipality and northern Ensenada Municipality, within northern Baja California state of northwestern Mexico. It is a major mountain range in the long Peninsular Ranges System, that extends from Southern California down the Baja California Peninsula into Baja California Sur state; the Sierra de Juárez begins just south of the international frontier with California and extends about 140 kilometres southwards. The highest peak in the range rises to about 1,980 meters elevation at 31° 30′ 34″ North Latitude and 115° 32′ 5″ West Longitude; the Laguna Mountains are on the north, the Sierra de San Pedro Mártir are on the south. The Sierra forms part of the Baja California Peninsular Ranges. According to the Mexican government agency, CONABIO, the Sierra de Juárez occupies a total area of 4,568 square kilometres 140 kilometres long and averaging about 33 kilometres wide. On the east the Sierra de Juárez rises from the desert valley containing the Laguna Salada Fault, a southern extension of the San Andres Fault.
The western slope of the Sierra is more gentle. The range is the location of the southern tip of the Great Basin Divide at a triple watershed point of the Great Basin, the Pacific Ocean, Gulf of California watersheds. A portion of the Sierra de Juárez is protected within Constitution 1857 National Park 72 kilometres east of Ensenada; the scenic Laguna Hanson, an important stopover for migratory birds, the endemic pine-oak forests habitat are within the park. The lower elevations of the western slopes of the Sierra de Juárez are in the California coastal sage and chaparral sub−ecoregion of the California chaparral and woodlands ecoregion; the lower elevations of the eastern slopes are in the Sonoran Desert ecoregion, with its unique desert flora. The California Fan Palm is near the southern natural limit of its range in the Sierra de Juárez; the higher elevations of the Sierra de Juárez, with those of the Sierra San Pedro Mártir, are in the Sierra Juarez and San Pedro Martir pine-oak forests ecoregion.
Pine species include Parry Piñon pine, lodgepole pine, sugar pine. Other evergreen species include incense cedar. Sagebrush is a common shrub of the understory; the coniferous forests of the two mountain ranges comprise a Sky island--an elevated temperate forest surrounded by lower, more arid lands. The western flank of the range lies at the southeastern extremity of the Mediterranean climate region, that extends across much of California and into northwestern Baja California. CONABIO lists the climates of the Sierra de Juarez as consisting of 30 percent desert, 7 percent steppe, 27 percent mesothermal with precipitation evenly distributed throughout the year, 36 percent Mediterranean with precipitation concentrated in the winter months; the Laguna Hanson weather station has a Csb climate, although the climate at this location verges on being Mediterranean with dry summers. In general the lower elevations are desert climates and the higher elevations receive more precipitation. Constitution 1857 National Park Peninsular Ranges topics Flora of the California chaparral and woodlands C. Michael Hogan.
2009. California Fan Palm: Washingtonia filifera. GlobalTwitcher.com, ed. Nicklas Stromberg World Wildlife Fund, ed.. "Sierra Juarez and Sierra Pedro Martir Pine-oak Forests". WildWorld Ecoregion Profile. National Geographic Society. Archived from the original on 2010-03-08. Astronautix.com: Sierra de Juárez
Peter of Verona
Saint Peter of Verona O. P. known as Saint Peter Martyr, was a 13th-century Italian Catholic priest. He was a celebrated preacher, he served as Inquisitor in Lombardy, was killed by an assassin, was canonized as a Catholic saint 11 months after his death, making this the fastest canonization in history. Thomas Agni of Leontino, Dominican archbishop of Cosenza, patriarch of Jerusalem, was the first to write a life of the blessed martyr, he had been his superior. He was born in the city of Verona into a family sympathetic to the Cathar heresy. Peter went to a Catholic school, to the University of Bologna, where he is said to have maintained his orthodoxy and at the age of fifteen, met Saint Dominic. Peter joined the Order of the Friars Preachers and became a celebrated preacher throughout northern and central Italy. From the 1230s on, Peter preached against heresy, Catharism, which had many adherents in thirteenth-century Northern Italy. Pope Gregory IX appointed him General Inquisitor for northern Italy in 1234. and Peter evangelized nearly the whole of Italy, preaching in Rome, Bologna and Como.
In 1243 he recommended the new Servite foundation to the pope for approval. In 1251, Pope Innocent IV recognized Peter's virtues, appointed him Inquisitor in Lombardy, he spent about six months in that office and it is unclear whether he was involved in any trials. His one recorded act was a declaration of clemency for those confessing heresy or sympathy to heresy. In his sermons he denounced heresy and those Catholics who professed the Faith by words, but acted contrary to it in deeds. Crowds followed him; because of this, a group of Milanese Cathars conspired to kill him. They hired one Carino of Balsamo. Carino's accomplice was Manfredo Clitoro of Giussano. On April 6, 1252, when Peter was returning from Como to Milan, the two assassins followed Peter to a lonely spot near Barlassina, there killed him and mortally wounded his companion, a fellow friar named Dominic. Carino struck Peter's head with an axe and attacked Domenico. Peter rose to his knees, recited the first article of the Symbol of the Apostles.
Offering his blood as a sacrifice to God, according to legend, he dipped his fingers in it and wrote on the ground: "Credo in Deum", the first words of the Apostles' Creed. The blow that killed him cut off the top of his head, but the testimony given at the inquest into his death confirms that he began reciting the Creed when he was attacked. Dominic was carried to Meda. According to Dominican tradition Peter conversed with the saints, including the virgin-martyrs Catherine and Cecilia. Once, when preaching to a vast crowd under the burning sun, the heretics challenged him to procure shade for his listeners; as he prayed, a cloud overshadowed the audience. Peter's body was carried to Milan and laid in the Church of Sant'Eustorgio, where an ornate mausoleum, the work of Balduccio Pisano, was erected to his memory. Since the eighteenth century this has been located in the Portinari Chapel. Many miracles were attributed to him while alive, more after his martyrdom. Peter was canonized by Pope Innocent IV on the fastest canonization in papal history.
St Peter the Martyr's feast day is 6 April. From 1586, when the feast day was inserted in the General Roman Calendar, to 1969, when it was removed on the grounds of the limited importance now attached to the saint internationally, the celebration was on 29 April; the Church of Santa Maria Antiqua in Verona is co-entitled to him. Carino, the assassin repented and confessed his crime, he converted to orthodoxy and became a lay brother in the Dominican convent of Forlì. He is the subject of a local cult as Blessed Carino of Balsamo; the sculptures on the great door of S. Anastasia, the Dominican Church in Verona, represent scenes from the life of St. Peter Martyr. Konrad von Marburg Pedro de Arbués Dondaine, Fr. Antoine, O. P. "Saint Pierre Martyr" Archivum Fratrum Praedicatorum 23: 66-162. Prudlo, Donald; the Martyred Inquisitor: The Life and Cult of Peter of Verona. Aldershot: Ashgate Press, 2008. Prudlo, Donald. "The Assassin-Saint: The Life and Cult of Carino of Balsamo", Catholic Historical Review, 94: 1-21.
Butler, Alban. The Lives of the Saints, Volume IV: April, 1866
Mauna Kea is a dormant volcano on the island of Hawaii. Its peak is 4,207.3 m above sea level. Most of the mountain is under water, when measured from its oceanic base, Mauna Kea is the tallest mountain in the world measuring over 10,000 m. Mauna Kea is about a million years old, has thus passed the most active shield stage of life hundreds of thousands of years ago. In its current post-shield state, its lava is more viscous. Late volcanism has given it a much rougher appearance than its neighboring volcanoes due to construction of cinder cones, decentralization of its rift zones, glaciation on its peak, weathering by the prevailing trade winds. Mauna Kea last is now considered dormant; the peak is about 38 m higher than its more massive neighbor. In Hawaiian mythology, the peaks of the island of Hawaii are sacred. An ancient law allowed only high-ranking aliʻi to visit its peak. Ancient Hawaiians living on the slopes of Mauna Kea relied on its extensive forests for food, quarried the dense volcano-glacial basalts on its flanks for tool production.
When Europeans arrived in the late 18th century, settlers introduced cattle and game animals, many of which became feral and began to damage the mountain's ecological balance. Mauna Kea can be ecologically divided into three sections: an alpine climate at its summit, a Sophora chrysophylla–Myoporum sandwicense forest on its flanks, an Acacia koa–Metrosideros polymorpha forest, now cleared by the former sugar industry, at its base. In recent years, concern over the vulnerability of the native species has led to court cases that have forced the Hawai'i Department of Land and Natural Resources to eradicate all feral species on the mountain. With its high elevation, dry environment, stable airflow, Mauna Kea's summit is one of the best sites in the world for astronomical observation. Since the creation of an access road in 1964, thirteen telescopes funded by eleven countries have been constructed at the summit; the Mauna Kea Observatories are used for scientific research across the electromagnetic spectrum and comprise the largest such facility in the world.
Their construction on a landscape considered sacred by Native Hawaiians continues to be a topic of debate. Mauna Kea is one of five volcanoes that form the island of Hawaii, the largest and youngest island of the Hawaiian–Emperor seamount chain. Of these five hotspot volcanoes, Mauna Kea is the fourth oldest and fourth most active, it began as a preshield volcano driven by the Hawaii hotspot around one million years ago, became exceptionally active during its shield stage until 500,000 years ago. Mauna Kea entered its quieter post-shield stage 250,000 to 200,000 years ago, is dormant. Mauna Kea does not have a visible summit caldera, but contains a number of small cinder and pumice cones near its summit. A former summit caldera may have been filled and buried by summit eruption deposits. Mauna Kea is over 32,000 km3 in volume, so massive that it and its neighbor, Mauna Loa, depress the ocean crust beneath it by 6 km; the volcano continues to slip and flatten under its own weight at a rate of less than 0.2 mm per year.
Much of its mass lies east of its present summit. Mauna Kea stands 4,207.3 m above sea level, about 38 m higher than its neighbor Mauna Loa, is the highest point in the state of Hawaii. Measured from its base on the ocean floor, it rises over 10,000 m greater than the elevation of Mount Everest above sea level. Like all Hawaiian volcanoes, Mauna Kea has been created as the Pacific tectonic plate has moved over the Hawaiian hotspot in the Earth's underlying mantle; the Hawaii island volcanoes are the most recent evidence of this process that, over 70 million years, has created the 6,000 km -long Hawaiian Ridge–Emperor seamount chain. The prevailing, though not settled, view is that the hotspot has been stationary within the planet's mantle for much, if not all of the Cenozoic Era. However, while Hawaiian volcanism is well understood and extensively studied, there remains no definite explanation of the mechanism that causes the hotspot effect. Lava flows from Mauna Kea overlapped in complex layers with those of its neighbors during its growth.
Most prominently, Mauna Kea is built upon older flows from Kohala to the northwest, intersects the base of Mauna Loa to the south. The original eruptive fissures in the flanks of Mauna Kea were buried by its post-shield volcanism. Hilo Ridge, a prominent underwater rift zone structure east of Mauna Kea, was once believed to be a part of the volcano; the shield-stage lavas that built the enormous main mass of the mountain are tholeiitic basalts, like those of Mauna Loa, created through the mixing of primary magma and subducted oceanic crust. They are covered by the oldest exposed rock strata on Mauna Kea, the post-shield alkali basalts of the Hāmākua Volcanics, which erupted between 250,000 and 70–65,000 years ago; the most recent volcanic flows are hawaiites and mugearites: they are the post-shield Laupāhoehoe Volcanics, erupted between 65,000 and 4,000 years ago. These changes in lava composition accompanied the slow reduction of the supply of magma to the summit, which led to weaker eruptions that gave way to isolated episodes associated with volcanic dormancy.
The Laupāhoehoe lavas are more viscous and contain more volatiles than the earlier tholeiitic basalts.