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Monday, April 27, 2020

Big Bend National Park

From Wikipedia, the free encyclopedia

Big Bend
IUCN category II (national park)
Canyon, Rio Grande, Texas.jpeg
The Rio Grande runs through Cañón de Santa Elena. Mexico on the left and Big Bend National Park, U.S. on the right.
Map showing the location of Big Bend
Map showing the location of Big Bend
Location in the United States
LocationChihuahuan Desert, Texas, United States
Nearest cityAlpine
Coordinates29°15′0″N 103°15′0″WCoordinates: 29°15′0″N 103°15′0″W
Area801,163 acres (3,242.19 km2)
EstablishedJune 12, 1944
Visitors440,091 (in 2018)
OperatorNational Park Service
WebsiteOfficial website 

Big Bend National Park is an American national park located in West Texas, bordering Mexico. The park has national significance as the largest protected area of Chihuahuan Desert topography and ecology in the United States. The park protects more than 1,200 species of plants, more than 450 species of birds, 56 species of reptiles, and 75 species of mammals.

Geological features in the park include sea fossils and dinosaur bones, as well as volcanic dikes. The area has a rich cultural history, from archeological sites dating back nearly 10,000 years to more recent pioneers, ranchers, and miners.

The park encompasses an area of 801,163 acres (1,251.8 sq mi; 3,242.2 km2). For more than 1,000 miles (1,600 km), the Rio Grande/Río Bravo forms the boundary between Mexico and the United States, and Big Bend National Park administers approximately 118 miles (190 km) along that boundary. The park was named after a large bend in the river, and the Texas—Mexico border.

Because the Rio Grande serves as an international boundary, the park faces unusual constraints while administering and enforcing park rules, regulations, and policies. In accordance with the Treaty of Guadalupe Hidalgo, the park's territory extends only to the center of the deepest river channel as the river flowed in 1848. The rest of the land south of that channel, and the river, lies within Mexican territory. The park is bordered by the protected areas of Parque Nacional Cañon de Santa Elena and Maderas del Carmen in Mexico.

Geography and climate

Park ranger on a horseback patrol near Santa Elena Canyon

According to the Köppen climate classification system, Big Bend National Park has a hot semi-arid climate (Bsh).

The park exhibits dramatic contrasts and its climate may be characterized as one of extremes. Dry and hot late spring and summer days often exceed 100 °F (38 °C) in the lower elevations. Winters are normally mild but subfreezing temperatures occasionally occur. Because of the range in altitude from about 1,800 feet (550 m) along the river to Emory Peak in the Chisos Mountains at 7,832 feet (2,387 m), a wide variation in available moisture and temperature exists throughout the park. These variations contribute to an exceptional diversity in plant and animal habitats. Some species in the park, such as the Chisos oak (Quercus graciliformis), are found nowhere else in the United States.

The 118 mi (190 km) of river that form the southern park boundary include the spectacular canyons of Santa Elena, Mariscal, and Boquillas. The Rio Grande, which meanders through this portion of the Chihuahuan Desert, has cut deep canyons with nearly vertical walls through three uplifts made primarily of limestone. Throughout the open desert areas, the highly productive Rio Grande riparian zone includes numerous plant and animal species and significant cultural resources. The vegetative belt extends into the desert along creeks and arroyos.

South of the border lie the Mexican states of Chihuahua and Coahuila and newly protected areas for flora and fauna, which are regions known as the Maderas del Carmen and the Cañón de Santa Elena.

Geology

Big Bend from space, 2002
 
Aerial view, 3D computer generated image
 
The oldest recorded tectonic activity in the park is related to the Paleozoic Marathon orogeny, although Proterozoic events (over 550 Mya) possibly have some deep control. The Marathon orogeny (part of the Ouachita-Marathon-Sonora orogenic belt) is part of thrusting of rocks from the South American Plate over the North American Plate. This can be best seen in the Persimmon Gap area of the park. This orogenic event is linked to the lack of Triassic- and Jurassic-age rocks in the park.

Between the Triassic and the Cretaceous, the South American Plate rifted from the North American Plate, resulting in the deposition of the Glen Rose Limestone, Del Carmen Limestone, Sue Peaks Formation, Santa Elena Limestone, Del Rio Clay, Buda Limestone, and Boquillas formations (preserved in the Sierra del Carmen–Santiago Mountains, Nine Point Mesa, Mariscal Mountain, and Mesa de Anguila areas). Also during this time, the Chihuahua trough formed as the Gulf of Mexico opened, which resulted in east-west striking normal faulting. As a result of this depositional time, dinosaur, forest and other fossils are preserved in the park.

Following the ending of rifting in the Late Cretaceous to the early Cenozoic, the Big Bend area was subjected to the Laramide orogeny. This period of (now east-west) compression caused the northeast-facing Mesa de Anguila (an uplifted monocline on the park's southwest margin), the southwest-facing Sierra del Carmen–Santiago Mountains (an uplifted and thrust-faulted monocline that forms the park's boundary on the east) and the Tornillo Basin. During the middle Cenozoic, most of the volcanic rocks, including the Chisos group, the Pine Canyon caldera complex, and the Burro Mesa Formation, formed.

The most recent tectonic activity in the park is basin and range faulting from the Neogene to Quaternary. This period of east-west extension has resulted in Estufa and Dehalo bolsons in the Chisos Mountains, as well as the Terlingua and Sierra del Carmen, Chalk Draw, and Burro Mesa faults. The Rio Grande has entered the Big Bend area roughly 2 million years ago, and since then, extensive erosion and downcutting have occurred.

Cultural resources

Cultural resources in the park range from the Paleo-Indian period 10,500 years ago through the historic period represented by Native American groups, such as the Chisos, Mescaleros, and Comanche. More recently, Spanish, Mexican, Anglo, and Irish settlers farmed, ranched, and mined in the area. 

Throughout the prehistoric period, humans found shelter and maintained open campsites throughout the park. The archeological record reveals an Archaic-period desert culture, whose inhabitants developed a nomadic hunting and gathering lifestyle that remained virtually unchanged for several thousand years. 

The historic cultural landscape centers upon various subsistence or commercial land uses. The riparian and tributary environments were used for subsistence and irrigation farming. Transportation networks, irrigation structures, simple domestic residences and outbuildings, and planed and terraced farm land lining the stream banks characterize these landscapes.

Human history

Pine Canyon Falls

During the early historic period (before 1535) several Indian groups were recorded as inhabiting the Big Bend. The Chisos Indians were a loosely organized group of nomadic hunters and gatherers who probably practiced limited agriculture on a seasonal basis. The origin of the Chisos Indians is not known. Linguistically, they were associated with the Conchos Indians of northern Chihuahua and northwestern Coahuila. Their language group spoke a variation of Uto-Aztecan, a language whose speakers ranged from central Mexico to the Great Basin of the U.S.

The Jumano was a nomadic group that traveled and traded throughout West Texas and southeastern New Mexico, but some historic records indicate they were enemies of the Chisos. Around the beginning of the 18th century, the Mescalero Apaches began to invade the Big Bend region and displaced the Chisos Indians. One of the last Native American groups to use the Big Bend was the Comanches, who passed through the park along the Comanche Trail on their way to and from periodic raids into the Mexican interior. These raids continued until the mid-19th century. The last of the great military leaders of the native peoples of the region was an Apache of Spanish ancestry named Alzate, who was active as late as the late 1860s.

The European presence in the region begins circa 1535 AD with the first Spanish explorations into this portion of North America. The expedition of Álvar Núñez Cabeza de Vaca passed near the Big Bend and was followed by other expeditions. Some of these expeditions were searching for gold and silver, or farm and ranch land. Others, such as those by the Franciscan missionaries, were intended to establish centers in which the natives could be evangelized. In an attempt to protect the northern frontier of the New Spain, from which emerged present-day Mexico, a line of presidios, or forts, was established along the Rio Grande in the late 18th century. The Presidio de San Vicente was built near present-day San Vicente, Coahuila, and the Presidio de San Carlos was built near present-day Manuel Benavides, Chihuahua. Some of the presidios were soon abandoned, because of financial difficulties and because they could not effectively stop Indian intrusions into Mexico. The soldiers and settlers of these presidios moved to newer presidios where the interests of the Spanish Empire were more defensible. Such was the case of Santa Rosa Maria del Sacramento, now Muzquiz, Coahuila. 

Very little study has been made of the Spanish occupation of the Big Bend following the abandonment of the presidios. In 1805, a Spanish settlement called Altares existed 30 mi (48 km) south of the Rio Grande. The region became a part of Mexico when it achieved its independence from Spain in 1821. Mexican families lived in the area when English-speaking settlers began arriving following the secession of Texas during the latter half of the 19th century. 

Following the end of the Mexican–American War in 1848, the U.S. Army made military surveys of the uncharted land of the Big Bend. Forts and outposts were established across Trans-Pecos Texas to protect migrating settlers from Indian attacks. A significant proportion of the soldiers in the late 1800s were African American and came to be called the "buffalo soldiers", a name apparently given to them by the Native Americans. Lieutenant Henry Flipper, the first American of African ancestry to graduate from West Point, served in Shafter, Texas, near the end of the 19th century. (Shafter, named for General William R. Shafter, lies west of the Big Bend along the highway from Presidio to Marfa.) Ranchers began to settle in the Big Bend about 1880, and by 1900, sheep, goat, and cattle ranches occupied most of the area. The delicate desert environment was soon overgrazed

In the late 19th and early 20th century, valuable mineral deposits were discovered and brought settlers who worked in the mines or supported the mines by farming or by cutting timber for the mines and smelters. Communities sprang up around the mines. Boquillas and Terlingua both resulted from mining operations. During this period, the Rio Grande flood plain was settled by farmers. Settlements developed with names like Terlingua Abajo, San Vicente, La Coyota, and Castolon. Often, no more than clusters of families were living and farming in the same area, and they were successful only to the degree that the land was able to support them. 

In the 1930s, many people who loved the Big Bend country saw that it was a land of unique contrast and beauty that was worth preserving for future generations. In 1933, the Texas Legislature passed legislation to establish Texas Canyons State Park. Later that year, the park was redesignated Big Bend State Park. In 1935, the United States Congress passed legislation that would enable the acquisition of the land for a national park. The State of Texas deeded the land that it had acquired to the federal government, and on June 12, 1944, Big Bend National Park became a reality. The park opened to visitors on July 1, 1944.

Flora and fauna

Despite its harsh desert environment, Big Bend has more than 1,200 species of plants (including 60 cactus species), over 600 species of vertebrates, and about 3,600 insect species. The variety of life is largely due to the diverse ecology and changes in elevation between the dry, hot desert, the cool mountains, and the fertile river valley. 

Most of the animals are not visible in the day, particularly in the desert. The park comes alive at night, with many of the animals foraging for food. About 150 cougar (Puma concolor) sightings are reported per year, despite the fact that only two dozen cougars live in the park. Other species that inhabit the park include coyote (Canis latrans), kangaroo rat (Dipodomys spp.), greater roadrunner (Geococcyx californianus), golden eagle (Aquila chrysaetos), gray fox (Urycon cinereoargenteus), collared peccary (Pecari tajacu), and black-tailed jackrabbit (Lepus californicus). Mexican black bears (Ursus americanus eremicus) are also present in the mountain areas. 

Pink bluebonnets
 
The variety of cactus and other plant life add color to the Big Bend region. Cactus species in the park include prickly pear (Opuntia spp.), claretcup (Echinocereus coccineus), and pitaya (E. enneacanthus). In the spring, the wildflowers are in full bloom and the yucca flowers display bright colors. Bluebonnets (Lupinus spp.) are prevalent in Big Bend, and white and pink bluebonnets are sometimes visible by the road. Other flowering plants such as the desert marigold (Baileya multiradiata), desert willow (Chilopsis linearis), ocotillo (Fouquieria splendens), rock nettle (Eucnide urens), and lechuguilla (Agave lechuguilla) abound in Big Bend. 

The first U.S. record of the northern tufted flycatcher (Mitrephanes phaeocercus), a Central American species, was from this site in November 1991. Birders also flock to the park, as it is home to the only area in the United States within the breeding range of the Colima warbler (Vermivora crissalis). 

Plans to reintroduce the Mexican wolf to Big Bend National Park were rejected in the late 1980s by the state of Texas. Disagreement over the reintroduction included the question of whether the park contained enough prey animals, such as deer and javelinas, to sustain a wolf population.

Tourism

Big Bend is one of the largest, most remote, and one of the least-visited national parks in the contiguous United States. In the 10 year period from 2007 to 2016, an average of about 352,000 visitors entered the park annually.

Balanced Rock in the Grapevine Hills
 
Big Bend's primary attraction is its hiking and backpacking trails. Particularly notable among these are the Chimneys Trail, which visits a rock formation in the desert; the Marufo Vega trail, a loop trail that passes through scenic canyons on the way to and from the Rio Grande; the South Rim trail which circles the high mountains of the Chisos; and the Outer Mountain Loop trail in the Chisos, which incorporates parts of the South Rim loop, descends into the desert along the Dodson Trail, and then returns to the Chisos Basin, completing a 30-mile loop. Other notable locations include Santa Elena Canyon, Grapevine Hills, and the Mule Ears, two imposing rock towers in the middle of the desert. Professional backpacking guide services provide trips in the park.

The park administers 118 miles (190 km) of the Rio Grande for recreational use. Professional river outfitters provide tours of the river. Use of a personal boat is permitted, but a free river float permit is required. In June 2009, the Department of Homeland Security began treating all float trips as trips that had left the country and required participants to have an acceptable form of identification such as a passport to re-enter the country.

Visitors often cross the Rio Grande to visit the Mexican village of Boquillas. The Department of Homeland Security closed the border crossing in 2002 due to increased security following the September 11 attacks, but in April 2013, the Boquillas crossing reopened as an official Class B Port of Entry between the U.S. and Mexico. It is open Wednesday through Sunday between 9 am and 6 pm.

With more than 450 species of birds recorded in the park, a widely popular activity is birdwatching. Many species stop in the park during their annual migrations.

Five paved roads are in Big Bend. Persimmon Gap to Panther Junction is a 28-mile (45 km) road from the north entrance of the park to park headquarters at Panther Junction. Panther Junction to Rio Grande Village is a 21-mile (34 km) road that descends 2,000 feet (610 m) from the park headquarters to the Rio Grande. Maverick Entrance Station to Panther Junction is a 23-mile (37 km) route from the western entrance of the park to the park headquarters. Chisos Basin Road is 6 miles (10 km) long and climbs to 5,679 feet (1,731 m) above sea level at Panther Pass before descending into the Chisos Basin. The 30-mile (48 km) Ross Maxwell Scenic Drive leads to the Castolon Historic District and Santa Elena Canyon.

Certified dark-sky park

In 2012, the park was designated an international dark-sky park by the International Dark-Sky Association. The association also recognized the park with its Gold Tier designation as "free from all but the most minor impacts of light pollution." Measurements made by the National Park Service show that Big Bend has the darkest skies in the contiguous United States. Thousands of stars, bright planets, and the Milky Way are visible on clear nights.

Gallery

Emory Peak's summit, the highest point in Big Bend National Park

Sunday, April 26, 2020

Channel Islands National Park

From Wikipedia, the free encyclopedia
 
Channel Islands National Park
IUCN category V (protected landscape/seascape)
Channel Islands National Park by Sentinel-2.jpg
Satellite view of Channel Islands National Park
Map showing the location of Channel Islands National Park
Map showing the location of Channel Islands National Park
Location of Channel Islands National Park
LocationSanta Barbara County & Ventura County, California, United States
Nearest citySanta Barbara
Coordinates34°0.5′N 119°25.0′WCoordinates: 34°0.5′N 119°25.0′W
Area249,561 acres (1,009.94 km2)
EstablishedMarch 5, 1980
Visitors366,250 (in 2018)
Governing bodyNational Park Service
WebsiteOfficial website 
Map of Channel Islands
 
A beach in Channel Islands National Park
 
Channel Islands National Park is an American national park that consists of five of the eight Channel Islands off the coast of the U.S. state of California, in the Pacific Ocean. Although the islands are close to the shore of densely populated Southern California, their isolation has left them relatively undeveloped. The park covers 249,561 acres (100,994 ha) of which 79,019 acres (31,978 ha) are owned by the federal government. The Nature Conservancy owns and manages 76% of Santa Cruz Island, the largest island in the park.

Channel Islands National Park is home to a wide variety of significant natural and cultural resources. Anacapa and Santa Barbara islands were designated as a national monument on April 26, 1938. All eight of the Channel Islands were designated as a biosphere reserve by UNESCO in 1976. Five islands, including Anacapa, Santa Barbara, Santa Cruz, San Miguel, and Santa Rosa, were redesignated as a national park on March 5, 1980. Channel Islands National Marine Sanctuary encompasses the waters six nautical miles around Channel Islands National Park.

History

Radiocarbon dating of a fire area near Arlington Canyon on the northwest coast of Santa Rosa Island shows human habitation from at least 37,000 years BP, while a burned mammoth bone was dated at 30,000 years BP. Similar fire areas in the same vicinity were dated at 27,000 years BP and 17,000 years BP, also believed to have been made by man. Additionally, a burned dwarf mammoth in a shell midden was dated to 12,500 years BP. A fire pit in a midden-humus layer was dated at 11,900 years BP, while above this layer was a stone chopper with a butchered and burned mammoth dated 11,800 years BP. Several more fire areas were dated at 11,000 years BP, while human bones, Arlington Springs Man, are dated to 10,000 years BP. A circular fishhook was dated at 4,800 years BP. Huge shell mounds appear at 2,000 years BP, while a camp fire in Skull Gulch was dated at 330 years BP.

Juan Rodríguez Cabrillo first observed the islands in 1542. The three northern channel islands were inhabited by an estimated two to three thousand Chumash, with eleven villages on Santa Cruz, eight on Santa Rosa, and two on San Miguel. In 1938 the Santa Barbara and Anacapa islands were designated a national monument. San Miguel, Santa Rosa and Santa Cruz islands were combined with the monument in 1980 to form modern-day Channel Islands National Park.

Oil spill

On January 28, 1969 an oil rig belonging to Union Oil experienced a blow-out 6 miles (9.7 km) off the coast of California. The resulting spill was, at the time, the largest oil spill to occur in United States territorial waters. Crews took approximately 11 days to seal the rupture using a cement plug, during which approximately 200,000 US gallons (760,000 litres; 170,000 imperial gallons) of crude oil spilled into the Pacific Ocean, creating an oil slick with an area of about 800 square miles (2,100 km2). Following the spill, tides carried the oil onto the beaches of the Anacapa, San Miguel, Santa Rosa and Santa Cruz islands.

This spill had a large impact on native wildlife of the Channel Islands. Much of the islands' seabird population was affected, with over an estimated 3,600 avians killed. Meanwhile, seals, dolphins and other sea life died and washed ashore on both the islands and the mainland.

This spill is the third largest oil spill in the United States, only surpassed by the Deepwater Horizon and the Exxon Valdez oil spills. It resulted in a 34,000 acres (14,000 ha) expansion of the Department of the Interior buffer zone in the channel and contributed to the formation of the Environmental Protection Agency.

The State of California Department of Oil and Gas noted 29 natural oil seeps between Point Conception and Rincon Point. The seeps were first noted by Father Pedro Font in 1776. Additionally, tar mounds are concentrated off the coast at Point Conception, Coal Oil Point, and Carpinteria. A natural oil seep also exists off the west coast of San Miguel Island. Finally, the distinctive odor of the petroliferous Monterey Shale is evident on the eastern end of Santa Cruz Island. The Chumash used the tar and oil from these seeps for caulking and adhesives.

Geography

The islands within the park extend along the Southern California coast from Point Conception near Santa Barbara to San Pedro, a neighborhood of Los Angeles. Park headquarters and the Robert J. Lagomarsino Visitor Center are located in the city of Ventura

The park consists of 249,354 acres (100,910 ha), half of which are under the ocean, and includes the islands of:

Climate

According to the Köppen climate classification system, Anacapa Island has a Warm-summer Mediterranean climate (Csb).

Climate data for Anacapa Island, elevation 36 ft (11 m), 1981-2010 normals, extremes 1981-2019
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Record high °F (°C) 81.5
(27.5)
77.8
(25.4)
83.5
(28.6)
90.8
(32.7)
86.0
(30.0)
97.4
(36.3)
85.1
(29.5)
81.6
(27.6)
90.4
(32.4)
92.6
(33.7)
94.1
(34.5)
77.9
(25.5)
97.4
(36.3)
Average high °F (°C) 62.4
(16.9)
61.4
(16.3)
62.0
(16.7)
63.6
(17.6)
64.9
(18.3)
66.8
(19.3)
68.8
(20.4)
69.7
(20.9)
70.1
(21.2)
69.0
(20.6)
65.9
(18.8)
61.8
(16.6)
65.6
(18.7)
Average low °F (°C) 51.6
(10.9)
52.3
(11.3)
52.4
(11.3)
51.7
(10.9)
54.6
(12.6)
57.3
(14.1)
59.7
(15.4)
60.9
(16.1)
60.7
(15.9)
59.1
(15.1)
55.3
(12.9)
52.0
(11.1)
55.7
(13.2)
Record low °F (°C) 37.0
(2.8)
39.5
(4.2)
40.5
(4.7)
39.7
(4.3)
47.6
(8.7)
49.7
(9.8)
53.7
(12.1)
53.1
(11.7)
53.3
(11.8)
47.5
(8.6)
44.6
(7.0)
36.9
(2.7)
36.9
(2.7)
Average precipitation inches (mm) 2.70
(69)
3.03
(77)
1.87
(47)
0.72
(18)
0.11
(2.8)
0.01
(0.25)
0.02
(0.51)
0.03
(0.76)
0.35
(8.9)
0.54
(14)
0.96
(24)
1.55
(39)
11.89
(302)
Average dew point °F (°C) 45.2
(7.3)
47.0
(8.3)
49.1
(9.5)
49.1
(9.5)
52.9
(11.6)
55.9
(13.3)
58.6
(14.8)
59.6
(15.3)
58.7
(14.8)
55.0
(12.8)
48.4
(9.1)
44.1
(6.7)
52.0
(11.1)

Geology

Weaver describes the geologic province of Anacapa as consisting of the islands of San Miguel, Santa Rosa, Santa Cruz, and Anacapia, plus the western portion of the Santa Monica Mountains. The province is to the south of the Santa Barbara embayment, and north of the Catalinia geologic province. Mesozoic in origin, the Anacapia province consists of Late Cretaceous to Miocene age marine sedimentary up to 23,000 feet thick, including 8,000 feet of volcanic rocks, overlain by Pleistocene terrace formations. Aligned with the Santa Monica mountains, the Northern Channel Islands form a mountain system 130 miles long. This island chain appears to be a faulted east-west trending anticline. Major faults include the Santa Cruz Island Fault and the Santa Rosa Island Fault.

A stratigraphic column would start with the oldest rocks, the Santa Cruz Island schist, forming an elongated core of the island, 10 miles long and 1.5 miles wide. This schist is intruded by the metamorphosed Alamos Tonalite, which has been dated 145 Ma. Just to the south of this schist is the Willows Diorite, also of the same age as the tonalite, or Late Jurassic. The only Cretaceous rocks consist of the Jalama Formation, found on San Miguel Island.

Lower Tertiary sequence of rocks are found within the Christi Anticline on the southwestern part of Santa Cruz Island. The sequence includes the Pozo Formation, Canada Formation, Jolla Vieja Formation, and the Cozy Dell Formation. San Miguel and Santa Rosa islands have the Middle to Late Eocene South Point Formation, while the Cozy Dell Formation is present on Santa Rosa, along with the Sespe Formation.

Middle Tertiary formations found on Santa Rosa and Santa Cruz include the Vaqueros Formation, while those two islands plus San Miguel have exposures of the Rincon Formation, and Monterey Formation. Santa Rosa and San Miguel have exposures of the basaltic and dacitic San Miguel Volcanics, which include pillow structures, while the San Onofre Breccia is found on Santa Rosa, Santa Cruz, and Anacapa. Santa Rosa Island Volcanics consist mainly of basaltic breccia, which erupted about 19 Ma. San Miguel Volcanics consist of basalt and andesite flows, which erupted between 17-18 Ma. Santa Cruz Island (SCI) Volcanics on the north side of the island consist of andesitic flows and volcaniclastics, overlying the San Onofre Breccia, and dated at about 16 Ma. The eruptive center is east of Devils Peak, and juxtaposed against the west-northwest trending strike-slip Santa Cruz Island Fault to the south. These 2400 m of SCI Volcanics have been further subdivide into four members, consisting of the lowermost Griffith Canyon, followed by Stanton Ranch, Devil's Peak, and Prisoner's Harbor, the uppermost. The Griffith Canyon Member consists of basaltic and andesitic epiclastic volcanic breccias. The Stanton Ranch Member consists of andesitic flows, flow breccias, and tuff breccias. The Devil's Peak Member consists of scoriaceous andesitic and dacitic flows. The Prisoner's Harbor Member consists of andesitic and dacitic transitional to rhyolitic flows, flow breccias, and tuffaceous volcaniclastic beds. Middle Miocene Conejo Volcanics correlate with the bulk of Anacapa's lava flows, volcanic and volcaniclastic breccias, which consist of vesicular and porphyritic andesite erupting about 16 Ma. About 1700 m are exposed, with two strata of San Onofre Breccia interbedded at the base. Cores taken from the east end of the island are andesitic in composition. Santa Barbara Island consists of basalt-basaltic andesite and andesite volcanic flows, which erupted 15-17 Ma.

During the Late Pleistocene, all of the islands were connected to the mainland, and between 11,000 and 20,000 years BP, the islands remained connected to each other as Santa Rosae. This allowed the Pleistocene mammoths to reach as far west as San Miguel. However, the pygmy mammoth underwent dwarfing as the Channel Islands became isolated. Another species which became extinct was the "giant" mouse. Mammoth remains include those of Mammuthus columbi, while the remains of Mammuthus exilis have been found on San Miguel, Santa Rosa, and Santa Cruz, ranging in age from 12,840 to >47,000 YBP. The 1994 Mammuthus exilis discovery on Santa Rosa near Carrington Point, was the first example of an in situ, almost complete, articulated skeleton.

Other geologic features of note on the islands include beachrock, eolianite, and caliche pseudomorphs.

Flora and fauna

Dolphins by Anacapa Island.

More than 2,000 species of plants and animals can be found within the park. However, only three mammals are endemic to the islands, one of which is the deer mouse (Peromyscus maniculatus) which is known to carry the sin nombre hantavirus. The spotted skunk and Channel Islands fox also are endemic. The island fence lizard is also endemic to the Channel Islands. Other animals in the park include island scrub jay, harbor seal, California sea lion, island fox, spotted skunk, island night lizard, barn owl, American kestrel, horned lark and meadowlark and California brown pelican. One hundred and forty-five of these species are unique to the islands and found nowhere else in the world. Marine life ranges from microscopic plankton to the endangered blue whale, the largest animal on earth. Archeological and cultural resources span a period of more than 10,000 years.

Tourism

The average annual visitation to the park's mainland visitor center was around 311,000 in the period from 2009 to 2018, with 366,250 visiting in 2018. The visitor center is located in the Ventura Harbor Village. The visitor center contains several exhibits that provide information regarding all five islands, native vegetation, marine life and cultural history. Also, visitors can enjoy a short film, free of charge, that provides an overview of all five islands. The visitor center is open every day, except Thanksgiving and Christmas, from 8:30AM–5:00PM. Visitation to the islands and waters is low, with about 30,000 visitors traveling to the islands, and another 60,000 who go only into park waters. Although most visitation occurs in the summer, migrating gray whales and spectacular wildflower displays attract visitors in the winter and spring. Autumn is an excellent time to travel to the park, as well as for diving, as the days are usually sunny, with minimal winds and clear ocean water. Camping is a popular activity on Santa Cruz Island, with visitors arriving at Prisoners Harbor [28] on the north shore and staying in the valley beyond. A new island visitor center opened at Scorpion Ranch on Santa Cruz Island on April 6, 2009.

Recreation

Channel Islands National Park offers a wide variety of recreation activities, kayaking through the sea caves being one of the most popular. Backpacking, camping, day hiking, scuba diving, and spearfishing are among the activities available to visitors. Channel Islands National Park is renowned for its large number of complex, beautiful sea caves. Based on ocean conditions and ferry availability, Scorpion Anchorage on Santa Cruz Island is the most visited area in the park for day and camping visitors. It is recommended that inexperienced visitors use caution when visiting the national park due to changing ocean conditions in this unique ecosystem. The National Park Service authorizes a small number of guide and outfitter services.

Gallery

Vessels

The CINP unit operates several vessels in the waters of the park, including the following:
  • Surf Ranger LCM-8 landing craft, 74 ft.
  • research diving boat Pacific Ranger 56 ft.
  • Sea Ranger II 58 ft.
  • Ocean Ranger 100 ft.
  • Sea Ranger 41 ft (retired).

Entropy (information theory)

From Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Entropy_(information_theory) In info...