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The Santa Cruz Mountains, part of the Pacific Coast Ranges, are a mountain range in central and northern California, United States. They form a ridge down the San Francisco Peninsula, south of San Francisco. They separate the Pacific Ocean from the San Francisco Bay and the Santa Clara Valley, and continue south to the Central Coast, bordering Monterey Bay and ending at the Salinas Valley. The range passes through the counties of San Mateo, Santa Clara, Santa Cruz, San Benito and Monterey, with the Pajaro River forming the southern boundary.
The San Lorenzo River is a 29.3 miles (47.2 km) long river whose headwaters originate in Castle Rock State Park in the Santa Cruz Mountains and flow south by southeast through the San Lorenzo Valley before passing through Santa Cruz and emptying into Monterey Bay and the Pacific Ocean.
The Santa Ana River is the largest river entirely within Southern California in the United States. It rises in the San Bernardino Mountains and flows for most of its length through San Bernardino and Riverside Counties, before cutting through the northern Santa Ana Mountains via Santa Ana Canyon and flowing southwest through urban Orange County to drain into the Pacific Ocean. The Santa Ana River is 96 miles (154 km) long, and its drainage basin is 2,650 square miles (6,900 km2) in size.
The Los Angeles Basin is a sedimentary basin located in southern California, in a region known as the Peninsular Ranges. The basin is also connected to an anomalous group of east-west trending chains of mountains collectively known as the Transverse Ranges. The present basin is a coastal lowland area, whose floor is marked by elongate low ridges and groups of hills that is located on the edge of the Pacific Plate. The Los Angeles Basin, along with the Santa Barbara Channel, the Ventura Basin, the San Fernando Valley, and the San Gabriel Basin, lies within the greater southern California region. On the north, northeast, and east, the lowland basin is bound by the Santa Monica Mountains and Puente, Elysian, and Repetto hills. To the southeast, the basin is bordered by the Santa Ana Mountains and the San Joaquin Hills. The western boundary of the basin is marked by the Continental Borderland and is part of the onshore portion. The California borderland is characterized by northwest trending offshore ridges and basins. The Los Angeles Basin is notable for its great structural relief and complexity in relation to its geologic youth and small size for its prolific oil production. Yerkes et al. identify five major stages of the basin's evolution, which began in the Upper Cretaceous and ended in the Pleistocene. This basin can be classified as an irregular pull-apart basin accompanied by rotational tectonics during the post-early Miocene.
The Salinas Valley is one of the major valleys and most productive agricultural regions in California. It is located west of the San Joaquin Valley and south of San Francisco Bay and the Santa Clara Valley.
Mount Hamilton is a mountain in the Diablo Range in Santa Clara County, California. The mountain's peak, at 4,265 feet (1,300 m), overlooks the heavily urbanized Santa Clara Valley and is the site of Lick Observatory, the world's first permanently occupied mountain-top observatory. The asteroid 452 Hamiltonia, discovered in 1899, is named after the mountain. Golden eagle nesting sites are found on the slopes of Mount Hamilton. On clear days, Mount Tamalpais, the Santa Cruz Mountains, Monterey Bay, the Monterey Peninsula, and even Yosemite National Park are visible from the summit of the mountain.
Almaden Quicksilver County Park is a 4,163 acres (17 km²) park that includes the grounds of former mercury ("quicksilver") mines adjacent to south San Jose, California, USA. The park's elevation varies greatly: the most used entrances are less than 600 feet above sea level, while the highest point in the park is over 1,700 feet above sea level.
The Pajaro River, is a U.S. river in the Central Coast region of California, forming part of the border between San Benito and Santa Clara Counties, the entire border between San Benito and Santa Cruz County, and the entire border between Santa Cruz and Monterey County. Flowing roughly east to west, the river empties into Monterey Bay, west of Watsonville, California.
Carbonera Creek is a 10.2-mile-long (16.4 km) watercourse in Santa Cruz County, California, that eventually flows to the San Lorenzo River.
Branciforte Creek is a 5.8-mile (9.3 km) long watercourse in Santa Cruz County, California, United States. Branciforte Creek rises on the western slopes of the Santa Cruz Mountains and discharges to the San Lorenzo River, which in turn empties into the Pacific Ocean. Within the State of California Branciforte Creek is classified within the Central Coast Basin. As of the year 2002, the State of California has designated Branciforte Creek as impaired with respect to turbidity and pathogens. The Branciforte watershed consists of 6,231 acres (25.22 km2), approximately 70 percent of which is covered with mixed evergreen forest, conifer forest and other undisturbed habitats.
Zayante Creek is a 10.3-mile-long (16.6 km) stream within the San Lorenzo River watershed in Santa Cruz County, California, United States. The U.S. government has designated Zayante Creek as impaired with respect to sediment. Lompico Creek, a tributary of Zayante Creek, is listed for impairment by pathogens. In the period 1998 to 2000 a restoration project was conducted for this stream to improve anadromous fish passage, rearing and spawning. There has been a permanent U.S. Geological Survey gauging station on Zayante Creek which has operated since the year 1959; the mean altitude of the Zayante Basin, carved within the western slopes of the Santa Cruz Mountains, is 1,000 feet (300 m). Significant tributaries to Zayante Creek are Lompico Creek and Bean Creek.
Bean Creek is a 9.1-mile-long (14.6 km) stream that rises on the western slopes of the Santa Cruz Mountains and discharges to Zayante Creek. This stream traverses relatively rugged, forested lands and is the locus of an important fossil bearing formation. These fossils are embedded in the Lower Santa Margarita Formation and include Astrodapsis spatiosus;also rare species of gastropod Thais cf. lapillis, and shark teeth The watershed area is 8.81 square miles (22.8 km2) and the peak flow of Bean Creek has been measured at 1,380 cubic feet (39 m3) per second. Since 2001 the Scotts Valley Water District has monitored regularly at three stations within Bean Creek for heavy metals and nitrates. Significant groundwater recharge occurs in the streambed of Bean Creek.
The Monterey Formation is an extensive Miocene oil-rich geological sedimentary formation in California, with outcrops of the formation in parts of the California Coast Ranges, Peninsular Ranges, and on some of California's off-shore islands. The type locality is near the city of Monterey, California. The Monterey Formation is the major source-rock for 37 to 38 billion barrels of oil in conventional traps such as sandstones. This is most of California's known oil resources. The Monterey has been extensively investigated and mapped for petroleum potential, and is of major importance for understanding the complex geological history of California. Its rocks are mostly highly siliceous strata that vary greatly in composition, stratigraphy, and tectono-stratigraphic history.
Bell Canyon is a major drainage of the Santa Ana Mountains in Orange County, California in the United States. Bell Creek flows about 14.4 miles (23.2 km) in a southerly direction to its confluence with San Juan Creek. The Bell Canyon drainage is located to the east and parallel to Cañada Gobernadora, and to the south of Trabuco Creek. After Trabuco Creek, it is the second largest tributary of San Juan Creek in terms of length and its watershed area of 26 square miles (67 km2).
The Vaqueros Formation is a sedimentary geologic unit primarily of Upper Oligocene and Lower Miocene age, which is widespread on the California coast and coastal ranges in approximately the southern half of the state. It is predominantly a medium-grained sandstone unit, deposited in a shallow marine environment. Because of its high porosity and nearness to petroleum source rocks, in many places it is an oil-bearing unit, wherever it has been configured into structural or stratigraphic traps by folding and faulting. Being resistant to erosion, it forms dramatic outcrops in the coastal mountains. Its color ranges from grayish-green to light gray when freshly broken, and it weathers to a light brown or buff color.
Lompico Creek is a tributary of Zayante Creek in Santa Cruz County, California, United States. The placename of Meehan is associated with a location near the mouth of Lompico Creek as it discharges to Zayante Creek. The geology of this watershed including the mainstem watershed of Zayante Creek is characterized by strata that include Vaqueros Sandstone and Lompico Sandstone.
The Sisquoc Formation is a sedimentary geologic unit widespread in Southern California, both on the coast and in mountains near the coast. Overlying the Monterey Formation, it is of upper Miocene and lower Pliocene age. The formation consists of claystone, mudstone, siltstone, shale, diatomite, and conglomerates, with considerable regional variation, and was deposited in a moderately deep marine environment at a depth of approximately 500–5,000 feet (150–1,520 m). Since some of its diatomites, along with those of the underlying Monterey Formation, are of unusual purity and extent, they can be mined as diatomaceous earth. France-based Imerys operates a mine in the Sisquoc and Monterey Formations in the hills south of Lompoc, California, the largest such operation in the world.
The Santa Cruz Mudstone is a geologic formation in California. The siliceous organic mudstones of the formation were deposited in deep water and fluvial environments. The formation overlies the Santa Margarita Sandstone and is overlain by the Purisima Formation. The Santa Cruz Mudstone was formerly considered part of the Monterey Formation. The formation preserves bivalve and echinoid fossils as well as vertebrates of Parabalaenoptera baulinensis and Otodus megalodon. The formation dates back to the Late Miocene period.
The geology of Arizona began to form in the Precambrian. Igneous and metamorphic crystalline basement rock may have been much older, but was overwritten during the Yavapai and Mazatzal orogenies in the Proterozoic. The Grenville orogeny to the east caused Arizona to fill with sediments, shedding into a shallow sea. Limestone formed in the sea was metamorphosed by mafic intrusions. The Great Unconformity is a famous gap in the stratigraphic record, as Arizona experienced 900 million years of terrestrial conditions, except in isolated basins. The region oscillated between terrestrial and shallow ocean conditions during the Paleozoic as multi-cellular life became common and three major orogenies to the east shed sediments before North America became part of the supercontinent Pangaea. The breakup of Pangaea was accompanied by the subduction of the Farallon Plate, which drove volcanism during the Nevadan orogeny and the Sevier orogeny in the Mesozoic, which covered much of Arizona in volcanic debris and sediments. The Mid-Tertiary ignimbrite flare-up created smaller mountain ranges with extensive ash and lava in the Cenozoic, followed by the sinking of the Farallon slab in the mantle throughout the past 14 million years, which has created the Basin and Range Province. Arizona has extensive mineralization in veins, due to hydrothermal fluids and is notable for copper-gold porphyry, lead, zinc, rare minerals formed from copper enrichment and evaporites among other resources.
The geology of California is highly complex, with numerous mountain ranges, substantial faulting and tectonic activity, rich natural resources and a history of both ancient and comparatively recent intense geological activity. The area formed as a series of small island arcs, deep-ocean sediments and mafic oceanic crust accreted to the western edge of North America, producing a series of deep basins and high mountain ranges.
References
- C. Michael Hogan, Leda Patmore, David Crimp et al., San Lorenzo Basin Groundwater Recharge and Water Quality Study, Earth Metrics Incorporated, Association of Monterey Bay Area Governments, July 7, 1978
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