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88-404: The Headlands sometimes create their own clouds when moist, warm Pacific Ocean breezes are pushed into higher, colder air, causing condensation , fog , fog drip and perhaps rain . The hills also get more precipitation than at sea level, for the same reason. However, despite being relatively wet, strong gusty Pacific winds prevent dense forests from forming. The many gaps, ridges, and valleys in

176-634: A black bear in the Headlands; the report was lent credence by a 2012 finding of bear scat on a hiking trail in the Kent Lake watershed, and another sighting on the Point Reyes National Seashore in 2011. River otters inhabit the freshwater lagoons and streams. Large numbers of water birds also migrate through the Headlands, including brown pelicans from May through October; and grebes , egrets , and great blue herons in

264-648: A central lagoon . Important human migrations occurred in the Pacific in prehistoric times. Modern humans first reached the western Pacific in the Paleolithic , at around 60,000 to 70,000 years ago. Originating from a southern coastal human migration out of Africa, they reached East Asia , Mainland Southeast Asia , the Philippines, New Guinea , and then Australia by making the sea crossing of at least 80 kilometres (50 mi) between Sundaland and Sahul . It

352-541: A mile from Rodeo Beach. The visitor center contains historical and natural history displays as well as a small bookstore/gift shop. Hiking maps and Park Service program information are available as well. Facilities include Presidio Fire Department Fire Station No. 2, located at building 1045 Fort Cronkhite. This fire station is operated by the National Park Service and houses one fire engine with cliff rescue capabilities. Public restrooms are available in

440-542: Is 4,280 m (14,040 ft; 2,340 fathoms), putting the total water volume at roughly 710,000,000 km (170,000,000 cu mi). Due to the effects of plate tectonics , the Pacific Ocean is currently shrinking by roughly 2.5 cm (1 in) per year on three sides, roughly averaging 0.52 km (0.20 sq mi) a year. By contrast, the Atlantic Ocean is increasing in size. Along

528-443: Is a process by which material is added to a tectonic plate at a subduction zone , frequently on the edge of existing continental landmasses . The added material may be sediment, volcanic arcs , seamounts , oceanic crust or other igneous features. Accretion involves the addition of material to a tectonic plate via subduction , the process by which one plate is forced under the other when two plates collide. The plate which

616-418: Is being forced down, the subducted plate, is pushed against the upper, over-riding plate. Sediment on the ocean floor of the subducting plate is often scraped off as the plate descends. This accumulated material is called an accretionary wedge (or accretionary prism), which is pushed against and attaches to the upper plate. In addition to accumulated ocean sediments, volcanic island arcs or seamounts present on

704-839: Is made up of multiple accreted terranes that collided with the Laurentian proto-continent , such as the Proterozoic Yavapai , Mazatzal , and Grenville Province Terranes. Accreted terranes along modern subduction plate boundaries include the Nankai accretionary complex of Japan (subduction of the Philippine Plate beneath the Eurasian Plate ), the Barbados Ridge in the Caribbean (subduction of

792-491: Is not known with any certainty what level of maritime technology was used by these groups – the presumption is that they used large bamboo rafts which may have been equipped with some sort of sail. The reduction in favourable winds for a crossing to Sahul after 58,000 B.P. fits with the dating of the settlement of Australia, with no later migrations in the prehistoric period. The seafaring abilities of pre-Austronesian residents of Island South-east Asia are confirmed by

880-616: Is the largest and deepest of Earth's five oceanic divisions . It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica ) in the south, and is bounded by the continents of Asia and Australia in the west and the Americas in the east. At 165,250,000 square kilometers (63,800,000 square miles) in area (as defined with a southern Antarctic border), this largest division of

968-642: The Americas , although evidence for this remains inconclusive. The first contact of European navigators with the western edge of the Pacific Ocean was made by the Portuguese expeditions of António de Abreu and Francisco Serrão , via the Lesser Sunda Islands , to the Maluku Islands , in 1512, and with Jorge Álvares 's expedition to southern China in 1513, both ordered by Afonso de Albuquerque from Malacca . The eastern side of

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1056-424: The Americas , more than 25,000 islands, large and small, rise above the surface of the Pacific Ocean. Multiple islands were the shells of former active volcanoes that have lain dormant for thousands of years. Close to the equator, without vast areas of blue ocean, are a dot of atolls that have over intervals of time been formed by seamounts as a result of tiny coral islands strung in a ring within surroundings of

1144-520: The Bering Sea in the Arctic to the northern extent of the circumpolar Southern Ocean at 60°S (older definitions extend it to Antarctica 's Ross Sea ), the Pacific reaches its greatest east–west width at about 5°N latitude , where it stretches approximately 19,800 km (12,300 mi) from Indonesia to the coast of Colombia  – halfway around the world, and more than five times

1232-487: The Golden Gate Raptor Observatory count and track this fall migration using bird-banding and radio-tracking techniques , all in cooperation with the National Park Service . The Marin Headlands are also home to black tail deer , mountain lions , bobcats , two types of foxes , coyotes , wild turkeys , hares , rabbits , raccoons , and skunks . In 2003, there was a reported sighting of

1320-704: The Pacific Plate onto the North American Plate . The process of subduction of ocean floor, followed by tectonic underplating to the underside of the over-riding plate, was first described here by Clyde Wahrhaftig in 1984. The primary rock types of the Marin Headlands include graywacke sandstone , radiolarian chert , serpentinite , pillow basalts , and shale . These rocks began their migration over one hundred million years ago from as far south as present-day Los Angeles . The erosion of

1408-601: The Pacific War ; however, by the end of that war, Japan was defeated and the U.S. Pacific Fleet was the virtual master of the ocean. The Japanese-ruled Northern Mariana Islands came under the control of the United States. Since the end of World War II, many former colonies in the Pacific have become independent states . The Pacific separates Asia and Australia from the Americas. It may be further subdivided by

1496-738: The Sirena Deep , is also located in the Mariana Trench. The western Pacific has many major marginal seas , including the Philippine Sea , South China Sea , East China Sea , Sea of Japan , Sea of Okhotsk , Bering Sea , Gulf of Alaska , Gulf of California , Mar de Grau , Tasman Sea , and the Coral Sea . In the early 16th century , Spanish explorer Vasco Núñez de Balboa crossed the Isthmus of Panama in 1513 and sighted

1584-725: The Southern Hemisphere . The North Equatorial Current , driven westward along latitude 15°N by the trade winds , turns north near the Philippines to become the warm Japan or Kuroshio Current . Turning eastward at about 45°N , the Kuroshio forks and some water moves northward as the Aleutian Current , while the rest turns southward to rejoin the North Equatorial Current. The Aleutian Current branches as it approaches North America and forms

1672-710: The Southwest Pacific around Oceania . The Pacific Ocean's mean depth is 4,000 meters (13,000 feet). Challenger Deep in the Mariana Trench , located in the northwestern Pacific, is the deepest known point in the world, reaching a depth of 10,928 meters (35,853 feet). The Pacific also contains the deepest point in the Southern Hemisphere , the Horizon Deep in the Tonga Trench , at 10,823 meters (35,509 feet). The third deepest point on Earth,

1760-685: The Strait of Magellan to the Philippines , the explorer indeed found the ocean peaceful; however, the Pacific is not always peaceful. Many tropical storms batter the islands of the Pacific. The lands around the Pacific Rim are full of volcanoes and often affected by earthquakes . Tsunamis , caused by underwater earthquakes, have devastated many islands and in some cases destroyed entire towns. The Martin Waldseemüller map of 1507

1848-818: The Western Hemisphere . The Southern Pacific Ocean harbors the Southeast Indian Ridge crossing from south of Australia turning into the Pacific-Antarctic Ridge (north of the South Pole ) and merges with another ridge (south of South America) to form the East Pacific Rise which also connects with another ridge (south of North America) which overlooks the Juan de Fuca Ridge . For most of Magellan's voyage from

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1936-673: The World Ocean and the hydrosphere covers about 46% of Earth's water surface and about 32% of the planet's total surface area, larger than its entire land area (148,000,000 km (57,000,000 sq mi)). The centers of both the Water Hemisphere and the Western Hemisphere , as well as the oceanic pole of inaccessibility , are in the Pacific Ocean. Ocean circulation (caused by the Coriolis effect ) subdivides it into two largely independent volumes of water that meet at

2024-583: The crab claw sail ) – it is likely that the progressive development of these technologies were related to the later steps of settlement into Near and Remote Oceania. Starting at around 2200 BCE, Austronesians sailed southwards to settle the Philippines . From, probably, the Bismarck Archipelago they crossed the western Pacific to reach the Marianas Islands by 1500 BCE, as well as Palau and Yap by 1000 BCE. They were

2112-991: The equator , the North Pacific Ocean and the South Pacific Ocean (or more loosely the South Seas ). The Pacific Ocean can also be informally divided by the International Date Line into the East Pacific and the West Pacific , which allows it to be further divided into four quadrants, namely the Northeast Pacific off the coasts of North America , the Southeast Pacific off South America , Northwest Pacific off Far Eastern / Pacific Asia , and

2200-424: The 1890s, the first military installations were built to prevent hostile ships from entering San Francisco Bay . The batteries at Kirby Cove , above Black Sands Beach, south of Rodeo Beach, and at Battery Mendell are examples of fortifications from the pre– World War I period. During World War II , Batteries Wallace, Townsley, and 129 on Hawk Hill were built into the hills to protect them from aerial bombardment and

2288-908: The Atlantic, the Strait of Magellan was at times patrolled by fleets sent to prevent the entrance of non-Spanish ships. On the western side of the Pacific Ocean the Dutch threatened the Spanish Philippines . The 18th century marked the beginning of major exploration by the Russians in Alaska and the Aleutian Islands , such as the First Kamchatka expedition and the Great Northern Expedition , led by

2376-533: The Atlantic. The andesite line is the most significant regional distinction in the Pacific. A petrologic boundary, it separates the deeper, mafic igneous rock of the Central Pacific Basin from the partially submerged continental areas of felsic igneous rock on its margins. The andesite line follows the western edge of the islands off California and passes south of the Aleutian arc , along

2464-735: The Chilean coast, the South Equatorial Current divides; one branch flows around Cape Horn and the other turns north to form the Peru or Humboldt Current . The climate patterns of the Northern and Southern Hemispheres generally mirror each other. The trade winds in the southern and eastern Pacific are remarkably steady while conditions in the North Pacific are far more varied with, for example, cold winter temperatures on

2552-613: The Coastal Miwok tribe. Before colonization, western expansion, and gentrification, the Miwok freely moved between the bay side of the peninsula and the ocean side, seasonally, for thousands of years. The growth of the San Francisco Bay Area has negatively impacted Miwok sacred sites, culture, and tribal visibility. Miwok continue to seek federal recognition. In the 18th century, Spanish and Mexican ranchers occupied

2640-844: The Danish-born Russian navy officer Vitus Bering . Spain also sent expeditions to the Pacific Northwest , reaching Vancouver Island in southern Canada, and Alaska. The French explored and colonized Polynesia , and the British made three voyages with James Cook to the South Pacific and Australia, Hawaii , and the North American Pacific Northwest . In 1768, Pierre-Antoine Véron , a young astronomer accompanying Louis Antoine de Bougainville on his voyage of exploration, established

2728-566: The Headlands at the visitor center parking lot, the parking lot near Rodeo Beach, and portable toilet facilities are available at the trailhead leading to the Point Bonita Lighthouse, along Conzelman Road near Black Sands Beach, at Battery Alexander dug into the hillside between Rodeo Beach and the Lighthouse, and at Battery 129 on Hawk Hill. Conference center facilities are located in former military buildings maintained by

Marin Headlands - Misplaced Pages Continue

2816-409: The Headlands include Point Bonita Lighthouse . In the 1960s, the government sold over 2,000 acres (8 km) of land in the Marin Headlands to a private developer who planned to build a city named Marincello . The development was to house 30,000 people in 50 apartment towers, vast tracts of single-family homes, a shopping center, and a hotel along the Headlands' pristine shoreline and hills. In 1970,

2904-668: The Headlands, eventually giving way to Portuguese immigrant dairy farmers (often from the Azores ) during the American period following the U.S. acquisition of California in the Mexican–American War . The Marin Headlands are the site of a number of historic military settlements and fortifications, including Fort Cronkhite , Fort Barry , a large number of bunkers and batteries , and the SF-88 Nike Missile silo. In

2992-473: The Marin Headlands on December 27: "...we came to anchor near the mouth of the bay, under a high and beautifully sloping hill, upon which herds of hundreds and hundreds of red deer [note: "red deer" is the European term for "elk"], and the stag, with his high branching antlers, were bounding about..." The Marin Headlands are underlain by geological formations created by the accretion of oceanic sediments from

3080-679: The Moluccas, between 1525 and 1527, Portuguese expeditions encountered the Caroline Islands , the Aru Islands , and Papua New Guinea . In 1542–43 the Portuguese also reached Japan. In 1564, five Spanish ships carrying 379 soldiers crossed the ocean from Mexico led by Miguel López de Legazpi , and colonized the Philippines and Mariana Islands . For the remainder of the 16th century, Spain maintained military and mercantile control, with ships sailing from Mexico and Peru across

3168-461: The NatureBridge campus (formerly known as the Headlands Institute), all in Fort Cronkhite; the Headlands Center for the Arts and the Marin Headlands Hostel at Fort Barry; and the Marin Headlands and Tennessee Valley Native Plant Nurseries. 37°49′40″N 122°30′22″W  /  37.82778°N 122.50611°W  / 37.82778; -122.50611 Pacific Ocean Main five oceans division: Further subdivision: The Pacific Ocean

3256-460: The Pacific Ring of Fire is the world's foremost belt of explosive volcanism . The Ring of Fire is named after the several hundred active volcanoes that sit above the various subduction zones. The Pacific Ocean is the only ocean which is mostly bounded by subduction zones. Only the central part of the North American coast and the Antarctic and Australian coasts have no nearby subduction zones. Accretion (geology) In geology , accretion

3344-429: The Pacific Ocean to the Philippines via Guam , and establishing the Spanish East Indies . The Manila galleons operated for two and a half centuries, linking Manila and Acapulco , in one of the longest trade routes in history. Spanish expeditions also arrived at Tuvalu , the Marquesas , the Cook Islands , the Solomon Islands , Vanuatu , the Marshalls and the Admiralty Islands in the South Pacific. Later, in

3432-399: The Pacific Ocean's irregular western margins lie many seas, the largest of which are the Celebes Sea , Coral Sea , East China Sea (East Sea), Philippine Sea , Sea of Japan , South China Sea (South Sea), Sulu Sea , Tasman Sea , and Yellow Sea (West Sea of Korea). The Indonesian Seaway (including the Strait of Malacca and Torres Strait ) joins the Pacific and the Indian Ocean to

3520-402: The Pacific in recorded history. They were part of a Spanish expedition to the Spice Islands that would eventually result in the first world circumnavigation . Magellan called the ocean Pacífico (or "Pacific" meaning, "peaceful") because, after sailing through the stormy seas off Cape Horn , the expedition found calm waters. The ocean was often called the Sea of Magellan in his honor until

3608-540: The Philippines already in 7000 BCE. Additional earlier migrations into Insular Southeast Asia, associated with Austroasiatic-speakers from Mainland Southeast Asia, are estimated to have taken place already in 15000 BCE. At around 1300 to 1200 BCE, a branch of the Austronesian migrations known as the Lapita culture reached the Bismarck Archipelago , the Solomon Islands , Vanuatu , Fiji , and New Caledonia . From there, they settled Tonga and Samoa by 900 to 800 BCE. Some also back-migrated northwards in 200 BCE to settle

Marin Headlands - Misplaced Pages Continue

3696-421: The Point Bonita YMCA, NatureBridge , and the Headlands Center for the Arts. The Cavallo Point conference center is in East Fort Baker on the eastern side of the peninsula. Other areas within Marin Headlands include Kirby Cove, Rodeo Lagoon , and Tennessee Cove . Various nonprofit organizations have facilities in Marin Headlands. These include the Marine Mammal Center , the Foundation for Deep Ecology , and

3784-528: The United States. Significant contributions to oceanographic knowledge were made by the voyages of HMS Beagle in the 1830s, with Charles Darwin aboard; HMS Challenger during the 1870s; the USS Tuscarora (1873–76); and the German Gazelle (1874–76). In Oceania, France obtained a leading position as imperial power after making Tahiti and New Caledonia protectorates in 1842 and 1853, respectively. After navy visits to Easter Island in 1875 and 1887, Chilean navy officer Policarpo Toro negotiated

3872-416: The andesite line and include New Guinea, the islands of New Zealand, and the Philippines. Some of these islands are structurally associated with nearby continents. High islands are of volcanic origin, and many contain active volcanoes. Among these are Bougainville , Hawaii, and the Solomon Islands. The coral reefs of the South Pacific are low-lying structures that have built up on basaltic lava flows under

3960-408: The andesite line. Within the closed loop of the andesite line are most of the deep troughs, submerged volcanic mountains, and oceanic volcanic islands that characterize the Pacific basin. Here basaltic lavas gently flow out of rifts to build huge dome-shaped volcanic mountains whose eroded summits form island arcs, chains, and clusters. Outside the andesite line, volcanism is of the explosive type, and

4048-409: The arctic, icing from October to May can present a hazard for shipping while persistent fog occurs from June to December. A climatological low in the Gulf of Alaska keeps the southern coast wet and mild during the winter months. The Westerlies and associated jet stream within the Mid-Latitudes can be particularly strong, especially in the Southern Hemisphere, due to the temperature difference between

4136-421: The base of a counter-clockwise circulation in the Bering Sea . Its southern arm becomes the chilled slow, south-flowing California Current . The South Equatorial Current , flowing west along the equator, swings southward east of New Guinea , turns east at about 50°S , and joins the main westerly circulation of the South Pacific, which includes the Earth-circling Antarctic Circumpolar Current . As it approaches

4224-406: The developer lost a lawsuit claiming the land was illegally zoned. The thousands of acres that would have been developed were sold to the Golden Gate National Recreation Area , allowing the open space to stay intact as a park. The area has views of San Francisco and, as such, is a tourist destination. One of the most common photographs of San Francisco is the view of the city from the Headlands with

4312-408: The diameter of the Moon. Its geographic center is in eastern Kiribati south of Kiritimati , just west from Starbuck Island at 4°58′S 158°45′W  /  4.97°S 158.75°W  / -4.97; -158.75 . The lowest known point on Earth – the Mariana Trench  – lies 10,911 m (35,797  ft ; 5,966 fathoms ) below sea level. Its average depth

4400-402: The difference between temperatures aloft and sea surface temperatures is the greatest; however, each particular basin has its own seasonal patterns. On a worldwide scale, May is the least active month, while September is the most active month. November is the only month in which all the tropical cyclone basins are active. The Pacific hosts the two most active tropical cyclone basins , which are

4488-434: The east and the islands of Kiribati in the southeast. Melanesia, to the southwest, includes New Guinea , the world's second largest island after Greenland and by far the largest of the Pacific islands. The other main Melanesian groups from north to south are the Bismarck Archipelago , the Solomon Islands , Santa Cruz , Vanuatu , Fiji and New Caledonia . The largest area, Polynesia , stretching from Hawaii in

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4576-423: The east coast of Russia contrasting with the milder weather off British Columbia during the winter months due to the preferred flow of ocean currents . In the tropical and subtropical Pacific, the El Niño Southern Oscillation (ENSO) affects weather conditions. To determine the phase of ENSO, the most recent three-month sea surface temperature average for the area approximately 3,000 km (1,900 mi) to

4664-403: The eastern edge of the Kamchatka Peninsula , the Kuril Islands , Japan, the Mariana Islands , the Solomon Islands , and New Zealand's North Island . The dissimilarity continues northeastward along the western edge of the Andes Cordillera along South America to Mexico, returning then to the islands off California. Indonesia, the Philippines, Japan, New Guinea, and New Zealand lie outside

4752-410: The eighteenth century. Magellan stopped at one uninhabited Pacific island before stopping at Guam in March 1521. Although Magellan himself died in the Philippines in 1521, Spanish navigator Juan Sebastián Elcano led the remains of the expedition back to Spain across the Indian Ocean and round the Cape of Good Hope , completing the first world circumnavigation in 1522. Sailing around and east of

4840-487: The equator into northern (North Pacific) and southern (South Pacific) portions. It extends from the Antarctic region in the South to the Arctic in the north. The Pacific Ocean encompasses approximately one-third of the Earth's surface, having an area of 165,200,000 km (63,800,000 sq mi) – larger than Earth's entire landmass combined, 150,000,000 km (58,000,000 sq mi). Extending approximately 15,500 km (9,600 mi) from

4928-469: The equator, which can have a salinity as low as 34 parts per thousand, is less salty than that found in the mid-latitudes because of abundant equatorial precipitation throughout the year. The lowest counts of less than 32 parts per thousand are found in the far north as less evaporation of seawater takes place in these frigid areas. The motion of Pacific waters is generally clockwise in the Northern Hemisphere (the North Pacific gyre ) and counter-clockwise in

5016-420: The first completely documented European landing in Australia (1606), in Cape York Peninsula , and Abel Janszoon Tasman circumnavigated and landed on parts of the Australian continental coast and arrived at Tasmania and New Zealand in 1642. In the 16th and 17th centuries, Spain considered the Pacific Ocean a mare clausum  – a sea closed to other naval powers. As the only known entrance from

5104-420: The first humans to reach Remote Oceania , and the first to cross vast distances of open water. They also continued spreading southwards and settling the rest of Maritime Southeast Asia , reaching Indonesia and Malaysia by 1500 BCE, and further west to Madagascar and the Comoros in the Indian Ocean by around 500 CE. More recently, it is suggested that Austronesians expanded already earlier, arriving in

5192-423: The great "Southern Sea" which he named Mar del Sur (in Spanish). Afterwards, the ocean's current name was coined by Portuguese explorer Ferdinand Magellan during the Spanish circumnavigation of the world in 1521, as he encountered favorable winds on reaching the ocean. He called it Mar Pacífico , which in Portuguese means 'peaceful sea'. Top large seas: Across the continents of Asia, Australia and

5280-463: The headlands. Hawks avoid flight over water since warm thermals that provide lift are rare. Abundant populations of small mammals protected by the park are one resource that helps maintain the large number of visiting raptors in the Headlands during the fall, but the strong onshore winds hitting the hills of the Headlands provide cold updrafts and hot late-summer days provide warm thermals that allow these birds to fly more efficiently. Volunteers with

5368-418: The high-caliber shells that would be fired by Axis battleships . The emplacements at the top of Hawk Hill were used for a radio station. During the Cold War , the gun batteries were decommissioned, but antiaircraft missile sites were built on the northern and southern sides of Rodeo Lagoon. Radar sites were placed atop Hawk Hill and Hill 88. At several locations, shelters were built into the hillsides to protect

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5456-405: The hills increase the wind speed and periodically, during powerful winter storms, these winds can reach hurricane force. In summer, breezes can still be very gusty, when the oceanic air and fog crosses the hills. The weather from November through February in the Headlands is dominated by periodic rainstorms that blow in from the Pacific, often originating in the Gulf of Alaska , and give the area

5544-464: The hillsides and construction activities during the military era have exposed some dramatic examples of these rock types for easy viewing, and the folding caused by tectonic action is visually evident in many places throughout the Headlands. The Marin Headlands are one of the featured field trips found in the Streetcar 2 Subduction online field trip guide series released in December 2019 by the American Geophysical Union . The Marin Headlands are home to

5632-439: The incorporation of the island into Chile with native Rapanui in 1888. By occupying Easter Island, Chile joined the imperial nations. By 1900 nearly all Pacific islands were in control of Britain, France, United States, Germany, Japan, and Chile. Although the United States gained control of Guam and the Philippines from Spain in 1898, Japan controlled most of the western Pacific by 1914 and occupied many other islands during

5720-417: The islands in the world. There are about 25,000 islands in the Pacific Ocean. The islands entirely within the Pacific Ocean can be divided into three main groups known as Micronesia , Melanesia and Polynesia . Micronesia, which lies north of the equator and west of the International Date Line , includes the Mariana Islands in the northwest, the Caroline Islands in the center, the Marshall Islands to

5808-519: The islands of eastern Micronesia (including the Carolines , the Marshall Islands , and Kiribati ), mixing with earlier Austronesian migrations in the region. This remained the furthest extent of the Austronesian expansion into Polynesia until around 700 CE when there was another surge of island exploration. They reached the Cook Islands , Tahiti , and the Marquesas by 700 CE; Hawaiʻi by 900 CE; Rapa Nui by 1000 CE; and finally New Zealand by 1200 CE. Austronesians may have also reached as far as

5896-418: The majority of its rainfall for the year. These cloudy, gray, and rainy days often are interspersed with cool but extremely clear ones. As winter turns to spring, the April-to-June weather tends to be dominated by powerful winds, less rain, and clearer skies. Summer days alternate between clear and warm intervals, giving way to foggy and cool periods. September and October bring the highest average temperatures of

5984-663: The military personnel from the use of nuclear, biological, or chemical weapons. Observation posts known as base end stations can also be found in the Headlands. A well-preserved example can be seen near the northern end of Rodeo Beach, and others are located near the Point Bonita Lighthouse and on Wolf Ridge as it slopes down to the sea. All military sites in the Headlands are now decommissioned and returned to civilian use. Some military facilities, such as SF-88, have been preserved as historical sites. Many historical buildings are now used by non-profit organizations, but maintained in their historical condition. Other historic landmarks in

6072-468: The north to New Zealand in the south, also encompasses Tuvalu , Tokelau , Samoa , Tonga and the Kermadec Islands to the west, the Cook Islands , Society Islands and Austral Islands in the center, and the Marquesas Islands , Tuamotu , Mangareva Islands , and Easter Island to the east. Islands in the Pacific Ocean are of four basic types: continental islands, high islands, coral reefs and uplifted coral platforms. Continental islands lie outside

6160-485: The northern Philippines , but also earlier groups associated with Austroasiatic-speakers , resulting in the modern peoples of Island Southeast Asia and Oceania. A later seaborne migration is the Neolithic Austronesian expansion of the Austronesian peoples . Austronesians originated from the island of Taiwan c.  3000 –1500 BCE. They are associated with distinctive maritime sailing technologies (notably outrigger boats , catamarans , lashed-lug boats, and

6248-433: The northwestern Pacific and the eastern Pacific. Pacific hurricanes form south of Mexico, sometimes striking the western Mexican coast and occasionally the Southwestern United States between June and October, while typhoons forming in the northwestern Pacific moving into southeast and east Asia from May to December. Tropical cyclones also form in the South Pacific basin , where they occasionally impact island nations. In

6336-451: The ocean was encountered by Spanish explorer Vasco Núñez de Balboa in 1513 after his expedition crossed the Isthmus of Panama and reached a new ocean. He named it Mar del Sur ("Sea of the South" or "South Sea" ) because the ocean was to the south of the coast of the isthmus where he first observed the Pacific. In 1520, navigator Ferdinand Magellan and his crew were the first to cross

6424-562: The ocean's surface. One of the most dramatic is the Great Barrier Reef off northeastern Australia with chains of reef patches. A second island type formed of coral is the uplifted coral platform, which is usually slightly larger than the low coral islands. Examples include Banaba (formerly Ocean Island) and Makatea in the Tuamotu group of French Polynesia . The volume of the Pacific Ocean, representing about 50.1 percent of

6512-432: The oceanic crust, and are therefore not easily subducted along with the oceanic crust that surrounds them. Instead, these less-dense bits of crust will collide with existing continental crust on the upper plate once the oceanic crust separating them is completely subducted. Most continents are composed of multiple accreted " terranes ", pieces of low-density continental crust with different origins. For example, North America

6600-439: The others require hikes of varying length and difficulty. There are many hiking and biking trails in the Headlands, several of which pass through coastal sage scrub , chaparral, and riparian areas. The raptor migration attracts birdwatchers to Hawk Hill, and waterfowl and seabirds can sometimes be seen on Rodeo Lagoon. The National Park Service maintains a visitor center near the intersection of Field Road and Bunker Road about

6688-581: The quest for Terra Australis ("the [great] Southern Land"), Spanish explorations in the 17th century, such as the expedition led by the Portuguese navigator Pedro Fernandes de Queirós , arrived at the Pitcairn and Vanuatu archipelagos, and sailed the Torres Strait between Australia and New Guinea, named after navigator Luís Vaz de Torres . Dutch explorers, sailing around southern Africa, also engaged in exploration and trade; Willem Janszoon , made

6776-466: The right, in a grove of Monterey pines , is a bench from which it is possible to view the Golden Gate, ship traffic passing beneath the bridge, and the city just beyond. The Headlands offers a number of beaches including Rodeo Beach (a pebble-covered, dark sand beach), Kirby Cove , Pirates' Cove, Black Sands Beach, Tennessee Beach, Muir Beach . Rodeo and Muir Beaches are accessible by car, while

6864-505: The settlement of Buka by 32,000 B.P. and Manus by 25,000 B.P. Journeys of 180 kilometres (110 mi) and 230 kilometres (140 mi) are involved, respectively. The descendants of these migrations today are the Negritos , Melanesians , and Indigenous Australians . Their populations in maritime Southeast Asia , coastal New Guinea , and Island Melanesia later intermarried with the incoming Austronesian settlers from Taiwan and

6952-504: The southeast of Hawaii is computed, and if the region is more than 0.5 °C (0.9 °F) above or below normal for that period, then an El Niño or La Niña is considered in progress. In the tropical western Pacific, the monsoon and the related wet season during the summer months contrast with dry winds in the winter which blow over the ocean from the Asian landmass. Worldwide, tropical cyclone activity peaks in late summer, when

7040-515: The spring, summer, and fall. The Headlands' status as a park protects the habitat and populations of these animals within just a few miles of San Francisco and its suburbs. In the waters surrounding the Headlands, harbor seals can be found year-round, gray whales can be seen in the spring and fall, and seabirds such as common murres and surf scoters swim within sight of shore. When Richard Henry Dana Jr. visited San Francisco Bay in 1835 he wrote about vast elk ( Cervus canadensis ) herds on

7128-409: The subducting plate may be amalgamated onto existing continental crust on the upper plate, increasing the continental landmass. Continental crust differs significantly from oceanic crust. Oceanic crust is primarily composed of basaltic rocks, which have a higher density than the rocks making up the majority of continental crust. Island arcs and other volcanic rocks are also lower in density than

7216-758: The towers of the Golden Gate Bridge just reaching out of the fog. On clear days, the site offers views of the bay, including the Farallon Islands , Angel Island , Alcatraz , the San Francisco–Oakland Bay Bridge , the Golden Gate Bridge and the East Bay. Where Conzelman Road runs along the southern shore of the Headlands and becomes one-way, a pedestrian path leads upwards to Hawk Hill. A short distance further on

7304-804: The tropics and Antarctica, which records the coldest temperature readings on the planet. In the Southern hemisphere, because of the stormy and cloudy conditions associated with extratropical cyclones riding the jet stream, it is usual to refer to the Westerlies as the Roaring Forties, Furious Fifties and Shrieking Sixties according to the varying degrees of latitude. The ocean was first mapped by Abraham Ortelius ; he called it Maris Pacifici following Ferdinand Magellan 's description of it as "a pacific sea" during his circumnavigation from 1519 to 1522. To Magellan, it seemed much more calm (pacific) than

7392-586: The west, and Drake Passage and the Strait of Magellan link the Pacific with the Atlantic Ocean on the east. To the north, the Bering Strait connects the Pacific with the Arctic Ocean . As the Pacific straddles the 180th meridian , the West Pacific (or western Pacific , near Asia) is in the Eastern Hemisphere , while the East Pacific (or eastern Pacific , near the Americas) is in

7480-534: The width of the Pacific with precision for the first time in history. One of the earliest voyages of scientific exploration was organized by Spain in the Malaspina Expedition of 1789–1794. It sailed vast areas of the Pacific, from Cape Horn to Alaska, Guam and the Philippines, New Zealand, Australia, and the South Pacific. Growing imperialism during the 19th century resulted in the occupation of much of Oceania by European powers, and later Japan and

7568-434: The world's oceanic water, has been estimated at some 714 million cubic kilometers (171 million cubic miles). Surface water temperatures in the Pacific can vary from −1.4 °C (29.5 °F), the freezing point of seawater, in the poleward areas to about 30 °C (86 °F) near the equator. Salinity also varies latitudinally, reaching a maximum of 37 parts per thousand in the southeastern area. The water near

7656-480: The year and the longest stretches of clear skies. The centerpoint of the Marin Headlands skyline is the 920-foot (280 m) Hawk Hill, the lookout point for the largest known flight of diurnal raptors in the Pacific states. Each autumn, from August into December, tens of thousands of hawks , kites , falcons , eagles , vultures , osprey , and harriers are funneled by the peninsular shape of Marin County into

7744-583: Was the first to show the Americas separating two distinct oceans. Later, the Diogo Ribeiro map of 1529 was the first to show the Pacific at about its proper size. (Inhabited dependent territories are denoted by the asterisk (*), with names of the corresponding sovereign states in round brackets. Associated states in the Realm of New Zealand are denoted by the hash sign (#).) Territories with no permanent civilian population. The Pacific Ocean has most of

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