Monthly Archives: December 2020

08-08/09-20, 09-12-20 – Rainbow Basin Natural Area

Rainbow Basin is a geological formation in the Calico Peaks range, located approximately 8 miles (13 km) north of Barstow in the Mojave Desert in San Bernardino County, California.

The Rainbow Basin has been designated a National Natural Landmark and is in the Bureau of Land Management managed Rainbow Basin Natural Area. Rainbow Basin is a mixture of private and public land, but it is managed by the Bureau of Land Management. It is accessible to the public via Irwin Road from Barstow to an unpaved loop road through the colorful basin.

The basin is notable for: the fantastic and beautiful shapes of its rock formations: its fossil beds, which have provided scientists with valuable information about life during the middle Miocene epoch, between 12 and 16 million years ago; and to the northeast the Calico Early Man Site.

Underneath Rainbow Basin is the massive batholith that lies below much of the western Mojave. Made from a type of rock called quartz monzonite, this batholith dates to either the Cretaceous, or possibly the late Jurassic period. Early in the Cenozoic Era this batholith was exposed in the area surrounding Rainbow Basin and bent downward as it underwent compression, to form a basin. Sediments deposited in this basin became the sedimentary rocks that are most visible in Rainbow Basin today. Further compression, uplift, and finally extension left these sedimentary formations deeply folded, the most prominent fold being the Barstow Syncline. These same stresses also produced several faults in the Rainbow Basin area.

The thick sedimentary layers can be divided into three distinct formations. The lowest is called the Jackhammer Formation, and it is composed of layers of sandstone, siltstone, limestone, and conglomerate, all probably dating to the early Miocene Epoch.

Above this is the Pickhandle Formation. The sediments making up this formation are mostly of volcanic origin – tuff, rhyolite and andesite, indicating that they were laid down during a period of active volcanism. That time was probably during the early Miocene.

The highest of the three formations is the Barstow Formation, which is made up of layers of conglomerate, limestone, sandstone, and shale. This formation dates to the middle to late Miocene and it contains one of the largest Cenozoic fossil assemblages in North America. Most of the sediment that makes up the layers in this formation was stream-laid, but there is a white layer of rhyolitic tuff (sometimes called marker tuff) near the top.

Finally, on top of everything else, is a relatively thin layer of fanglomerate (alluvial fan deposits) laid down during the late Pleistocene. Differential erosion of rocks of different hardness finished the job of sculpting the formations into the fantastic shapes that can be seen in Rainbow Basin today.

Source: Wikipedia
https://en.wikipedia.org/wiki/Rainbow_Basin

07-17-20 – Trona Pinnacles NEOWISE

The Trona Pinnacles are an unusual geological feature in the California Desert National Conservation Area. The landscape consists of more than 500 tufa spires (porous rock formed as a deposit when springs interact with other bodies of water), some as high as 140 feet (43 m), rising from the bed of the Searles Lake (dry) basin. The pinnacles vary in size and shape from short and squat to tall and thin, and are composed primarily of calcium carbonate (tufa). They now sit isolated and slowly crumbling away near the south end of the valley, surrounded by many square miles of flat, dried mud and with stark mountain ranges at either side.

During the Pleistocene, massive runoff spilled from the Sierra Nevada into a chain of inland seas. The system of interconnected lakes stretched from Mono Lake to Death Valley and included Searles Lake. Deep beneath Searles Lake, calcium-rich groundwater and alkaline lake water combined to grow tufa formations. Similar (modern) formations can be found today at Mono Lake to the north. Known as tufa pinnacles, these strange shapes formed underwater 10,000 to 100,000 years ago. The pinnacles did not all form at the same time. They are divided by age and elevation into three groups. The groups are dubbed the northern, middle, and southern groups because they formed during three ice ages.

The northern group is the youngest at 11,000 to 25,000 years old. These are the best examples of what are known as tufa towers. The northern group also include shapes called tombstones, ridges and cones. The small middle group claims only 100 spires, but boasts the tallest “tower”, rising 140 feet (43 m). The southern group, includes 200 tufa formations aged 32,000 to 100,000 years old.

The Pinnacles are recognizable in more than a dozen hit movies. Over thirty film projects a year are shot among the tufa pinnacles, including backdrops for car commercials and sci-fi movies and television series such as Battlestar Galactica, Buck Rogers, Star Trek V: The Final Frontier, Disney’s Dinosaur, The Gate II: Trespassers, Lost in Space, and Planet of the Apes. The music video for Lady Gaga’s 2020 single “Stupid Love” was also filmed here.

Source: Wikipedia
https://en.wikipedia.org/wiki/Trona_Pinnacles

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C/2020 F3 (NEOWISE) or Comet NEOWISE is a long period comet with a near-parabolic orbit discovered on March 27, 2020, by astronomers during the NEOWISE mission of the Wide-field Infrared Survey Explorer (WISE) space telescope. At that time, it was an 18th-magnitude object, located 2 AU (300 million km; 190 million mi) away from the Sun and 1.7 AU (250 million km; 160 million mi) away from Earth.

NEOWISE is known for being the brightest comet in the northern hemisphere since Comet Hale–Bopp in 1997. It was widely photographed by professional and amateur observers and was even spotted by people living near city centers and areas with light pollution. While it was too close to the Sun to be observed at perihelion, it emerged from perihelion around magnitude 0.5 to 1, making it bright enough to be visible to the naked eye. Under dark skies, it could be seen with the naked eye and remained visible to the naked eye throughout July 2020. By July 30, the comet was about magnitude 5, but binoculars were required near urban areas to locate the comet.

Source: Wikipedia
https://en.wikipedia.org/wiki/Comet_NEOWISE

07-16-20 – Mojave NEOWISE

C/2020 F3 (NEOWISE) or Comet NEOWISE is a long period comet with a near-parabolic orbit discovered on March 27, 2020, by astronomers during the NEOWISE mission of the Wide-field Infrared Survey Explorer (WISE) space telescope. At that time, it was an 18th-magnitude object, located 2 AU (300 million km; 190 million mi) away from the Sun and 1.7 AU (250 million km; 160 million mi) away from Earth.

NEOWISE is known for being the brightest comet in the northern hemisphere since Comet Hale–Bopp in 1997. It was widely photographed by professional and amateur observers and was even spotted by people living near city centers and areas with light pollution. While it was too close to the Sun to be observed at perihelion, it emerged from perihelion around magnitude 0.5 to 1, making it bright enough to be visible to the naked eye. Under dark skies, it could be seen with the naked eye and remained visible to the naked eye throughout July 2020. By July 30, the comet was about magnitude 5, but binoculars were required near urban areas to locate the comet.

Source: Wikipedia
https://en.wikipedia.org/wiki/Comet_NEOWISE

06-07-20 – Alabama Hills National Scenic Area

The Alabama Hills are a range of hills and rock formations near the eastern slope of the Sierra Nevada in the Owens Valley, west of Lone Pine in Inyo County, California.

Though geographically separate from the Sierra Nevada, they are part of the same geological formation. The rounded contours of the Alabamas contrast with the sharp ridges of the Sierra Nevada to the west. Though this might suggest that they formed from a different orogeny, the Alabamas are the same age as the Sierra Nevada. The difference in wear can be accounted for by different patterns of erosion.

Dozens of natural arches are among the main attractions at the Alabama Hills. They can be accessed by short hikes from the Whitney Portal Road, the Movie Flat Road and the Horseshoe Meadows Road. Among the notable features of the area are: Mobius Arch, Lathe Arch, the Eye of Alabama and Whitney Portal Arch.

The Alabama Hills were named for the CSS Alabama, a Confederate warship deployed during the American Civil War. When news of the ship’s exploits reached prospectors in California sympathetic to the Confederates, they named many mining claims after the ship, and the name came to be applied to the entire range. When the Alabama was finally sunk off the coast of Normandy by the USS Kearsarge in 1864, prospectors sympathetic to the North named a mining district, a mountain pass, a mountain peak, and a town after the Kearsarge.

The Alabama Hills are a popular filming location for television and movie productions, especially Westerns set in an archetypical “rugged” environment. Since the early 1920s, 150 movies and about a dozen television shows have been filmed here, including Tom Mix films, Hopalong Cassidy films, The Gene Autry Show, The Lone Ranger and Bonanza. Meanwhile, Classics such as Gunga Din, The Walking Hills, Yellow Sky, Springfield Rifle, The Violent Men, Bad Day at Black Rock (1955), the Budd Boetticher/Randolph Scott “Ranown” westerns, part of How the West Was Won, and Joe Kidd. In the late 1940s and early 50s the area was also a popular location for the films of B-western actor Tim Holt.

Source: Wikipedia
https://en.wikipedia.org/wiki/Alabama_Hills