North American Plate
The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, parts of Iceland and the Azores. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia; the plate includes both oceanic crust. The interior of the main continental landmass includes. Along most of the edges of this craton are fragments of crustal material called terranes, accreted to the craton by tectonic actions over a long span of time, it is thought. The southerly boundary with the Cocos Plate to the west and the Caribbean Plate to the east is a transform fault, represented by the Swan Islands Transform Fault under the Caribbean Sea and the Motagua Fault through Guatemala; the parallel Septentrional and Enriquillo–Plantain Garden faults, which run through the island of Hispaniola and bound the Gonâve Microplate, are a part of the boundary. The rest of the southerly margin which extends east to the Mid Atlantic Ridge and marks the boundary between the North American Plate and the South American Plate is vague but located near the Fifteen-Twenty Fracture Zone around 16°N.
On the northerly boundary is a continuation of the Mid-Atlantic ridge called the Gakkel Ridge. The rest of the boundary in the far northwestern part of the plate extends into Siberia; this boundary continues from the end of the Gakkel Ridge as the Laptev Sea Rift, on to a transitional deformation zone in the Chersky Range the Ulakhan Fault between it and the Okhotsk Plate, the Aleutian Trench to the end of the Queen Charlotte Fault system. The westerly boundary is the Queen Charlotte Fault running offshore along the coast of Alaska and the Cascadia subduction zone to the north, the San Andreas Fault through California, the East Pacific Rise in the Gulf of California, the Middle America Trench to the south. On its western edge, the Farallon Plate has been subducting under the North American Plate since the Jurassic Period; the Farallon Plate has completely subducted beneath the western portion of the North American Plate leaving that part of the North American Plate in contact with the Pacific Plate as the San Andreas Fault.
The Juan de Fuca, Gorda, Rivera and Nazca plates are remnants of the Farallon Plate. The boundary along the Gulf of California is complex; the Gulf is underlain by the Gulf of California Rift Zone, a series of rift basins and transform fault segments between the northern end of the East Pacific Rise in the mouth of the gulf to the San Andreas Fault system in the vicinity of the Salton Trough rift/Brawley seismic zone. It is accepted that a piece of the North American Plate was broken off and transported north as the East Pacific Rise propagated northward, creating the Gulf of California. However, it is as yet unclear whether the oceanic crust east of the Rise and west of the mainland coast of Mexico is a new plate beginning to converge with the North American Plate, consistent with the standard model of rift zone spreading centers generally. A few hotspots are thought to exist below the North American Plate; the most notable hotspots are the Yellowstone, Jemez Lineament, Anahim hotspots. These are thought to be caused by a narrow stream of hot mantle convecting up from the Earth's core–mantle boundary called a mantle plume, although some geologists think that upper-mantle convection is a more cause.
The Yellowstone and Anahim hotspots are thought to have first arrived during the Miocene period and are still geologically active, creating earthquakes and volcanoes. The Yellowstone hotspot is most notable for the Yellowstone Caldera and the many calderas that lie in the Snake River Plain while the Anahim hotspot is most notable for the Anahim Volcanic Belt found in the Nazko Cone area. For the most part, the North American Plate moves in a southwest direction away from the Mid-Atlantic Ridge; the motion of the plate cannot be driven by subduction as no part of the North American Plate is being subducted, except for a small section comprising part of the Puerto Rico Trench. One recent study suggests. Geologic timeline of Western North America New Madrid Seismic Zone, an ancient intraplate fault zone within the North American Plate, notable as early as 1699 Notes
Geographic Names Information System
The Geographic Names Information System is a database that contains name and locative information about more than two million physical and cultural features located throughout the United States of America and its territories. It is a type of gazetteer. GNIS was developed by the United States Geological Survey in cooperation with the United States Board on Geographic Names to promote the standardization of feature names; the database is part of a system that includes bibliographic references. The names of books and historic maps that confirm the feature or place name are cited. Variant names, alternatives to official federal names for a feature, are recorded; each feature receives a permanent, unique feature record identifier, sometimes called the GNIS identifier. The database never removes an entry, "except in cases of obvious duplication." The GNIS accepts proposals for new or changed names for U. S. geographical features. The general public can make proposals at the GNIS web site and can review the justifications and supporters of the proposals.
The Bureau of the Census defines Census Designated Places as a subset of locations in the National Geographic Names Database. U. S. Postal Service Publication 28 gives standards for addressing mail. In this publication, the postal service defines two-letter state abbreviations, street identifiers such as boulevard and street, secondary identifiers such as suite. Canadian Geographical Names Data Base, a similar, but non-public-domain, database for locations within Canada only GEOnet Names Server, a similar database for locations outside the United States United Nations Conference on the Standardization of Geographical Names U. S. Department of the Interior, U. S. Geological Survey, National Mapping Division, Digital Gazeteer: Users Manual. Least Heat Moon, Blue Highways: A Journey Into America. ISBN 0-316-35329-9 Jouris, All Over The Map, ISBN 0-89815-649-1 Report: "Countries, Areas of Special Sovereignty, Their Principal Administrative Divisions," Federal Information Processing Standards, FIPS 10-4.
Standard was withdrawn in September 2008, See Federal Register Notice: Vol. 73, No. 170, page 51276 Report: "Principles and Procedures: Domestic Geographic Names," U. S. Board on Geographic Names, 1997. U. S. Postal Service Publication 28. U. S. Board on Geographic Names website Geographic Names Information System Proposals from the general public Meeting minutes
Geological Society of America
The Geological Society of America is a nonprofit organization dedicated to the advancement of the geosciences. The society was founded in Ithaca, New York, in 1888 by Alexander Winchell, John J. Stevenson, Charles H. Hitchcock, John R. Procter and Edward Orton and has been headquartered at 3300 Penrose Place, Colorado, USA, since 1967. GSA began with 100 members under James Hall. In 1889 Mary Emilie Holmes became its first female member, it grew but to 600 members until 1931, when a nearly $4 million endowment from 1930 president R. A. F. Penrose Jr. jumpstarted GSA's growth. As of December 2017, GSA had more than 25,000 members in over 100 countries; the society has six regional sections in North America, three interdisciplinary interest groups, eighteen specialty divisions. The stated mission of GSA is "to advance geoscience research and discovery, service to society, stewardship of Earth, the geosciences profession." Its main activities are sponsoring scientific meetings and publishing scientific literature the peer-reviewed journals Geological Society of America Bulletin, published continuously since 1889, Geology, published since 1973.
In 2005, GSA introduced its online-only journal Geosphere, in February 2009, GSA began publishing Lithosphere. Both Geosphere and Lithosphere are open access as of 2018. GSA's monthly news and science magazine, GSA Today, is open access online. GSA publishes two books series, field guides, maps and charts. A third major activity is awarding research grants to graduate students. GSA issues Position Statements "in support of and consistent with the GSA's Vision and Mission to develop consensus on significant professional and societal issues of relevance to the geosciences community. Position Statements and adopted through a well-defined process, provide the basis for statements made on behalf of the GSA before government bodies and agencies and communicated to the media and the general public."For example, in 2006, the GSA adopted a Position Statement on Global Climate Change: The Geological Society of America supports the scientific conclusions that Earth’s climate is changing. Furthermore, the potential implications of global climate change and the time scale over which such changes will occur require active, long-term planning.
Current predictions of the consequences of global climate change include: rising sea level, significant alteration of global and regional climatic patterns with an impact on water availability, fundamental changes in global temperature distribution, melting of polar ice, major changes in the distribution of plant and animal species. While the precise magnitude and rate of climate change cannot be predicted with absolute certainty, significant change will affect the planet and stress its inhabitants. Past presidents of the Geological Society of America: Penrose Medal Arthur L. Day Medal Meinzer Award Kirk Bryan Award G K Gilbert Award Florence Bascom Mary C. Rabbitt Doris M. Curtis Outstanding Woman in Science Award GSA Official Website
San Bernardino County, California
San Bernardino County the County of San Bernardino, is a county located in the southern portion of the U. S. state of California, is located within the Greater Los Angeles area. As of the 2010 U. S. Census, the population was 2,035,210, making it the fifth-most populous county in California, the 12th-most populous in the United States; the county seat is San Bernardino. While included within the Greater Los Angeles area, San Bernardino County is included in the Riverside–San Bernardino–Ontario metropolitan statistical area, as well as the Los Angeles–Long Beach combined statistical area. With an area of 20,105 square miles, San Bernardino County is the largest county in the United States by area, although some of Alaska's boroughs and census areas are larger; the county is close to the size of West Virginia. It is larger than each of the nine smallest states, larger than the four smallest states combined, larger than 70 sovereign nations; this vast county stretches from where the bulk of the county population resides (in two Census County Divisions, holding 1,422,745 people as of the 2010 Census, covering the 450 square miles, across the thinly populated deserts and mountains.
It spans an area from south of the San Bernardino Mountains in San Bernardino Valley, to the Nevada border and the Colorado River. Spanish Missionaries from Mission San Gabriel Arcángel established a church at the village of Politania in 1810. Father Francisco Dumetz named the church San Bernardino on May 20, 1810, after the feast day of St. Bernardino of Siena; the Franciscans gave the name San Bernardino to the snowcapped peak in Southern California, in honor of the saint and it is from him that the county derives its name. In 1819, they established the San Bernardino de Sena Estancia, a mission farm in what is now Redlands. Following Mexican independence from Spain in 1821, Mexican citizens were granted land grants to establish ranchos in the area of the county. Rancho Jurupa in 1838, Rancho Cucamonga and El Rincon in 1839, Rancho Santa Ana del Chino in 1841, Rancho San Bernardino in 1842 and Rancho Muscupiabe in 1844. Agua Mansa was the first town in what became San Bernardino County, settled by immigrants from New Mexico on land donated from the Rancho Jurupa in 1841.
Following the purchase of Rancho San Bernardino, the establishment of the town of San Bernardino in 1851 by Mormon colonists, San Bernardino County was formed in 1853 from parts of Los Angeles County. Some of the southern parts of the county's territory were given to Riverside County in 1893. According to the U. S. Census Bureau, the county has a total area of 20,105 square miles, of which 20,057 square miles is land and 48 square miles is water, it is the largest county by the largest in the United States. It is larger than the states of New Jersey, Connecticut and Rhode Island combined, it borders both Arizona. The bulk of the population two million, live in the 480 square miles south of the San Bernardino Mountains adjacent to Riverside and in the San Bernardino Valley. Over 300,000 others live just north of the San Bernardino Mountains, agglomerating around Victorville covering 280 square miles in Victor Valley, adjacent to Los Angeles County. Another 100,000 people live scattered across the rest of the sprawling county.
The Mojave National Preserve covers some of the eastern desert between Interstate 15 and Interstate 40. The desert portion includes the cities of Needles next to the Colorado River and Barstow at the junction in Interstate 15 and Interstate 40. Trona is at the northwestern part of the county west of Death Valley; this national park within Inyo County has a small portion of land within the San Bernardino County. The largest metropolitan area in the Mojave Desert part of the county is Victor Valley, with the incorporated localities of Adelanto, Apple Valley and Victorville. Further south, a portion of Joshua Tree National Park overlaps the county near the High Desert area, in the vicinity of Twentynine Palms; the remaining towns make up the remainder of the High Desert: Pioneertown, Yucca Valley, Joshua Tree and Morongo Valley. The mountains are home to the San Bernardino National Forest, include the communities of Crestline, Lake Arrowhead, Running Springs, Big Bear City, Forest Falls, Big Bear Lake.
The San Bernardino Valley is at the eastern end of the San Gabriel Valley. The San Bernardino Valley includes the cities of Ontario, Chino Hills, Fontana, Colton, Grand Terrace, Rancho Cucamonga, San Bernardino, Loma Linda, Highland and Yucaipa. Angeles National Forest Death Valley National Park Havasu National Wildlife Refuge Joshua Tree National Park Mojave National Preserve San Bernardino National Forest There are at least 35 official wilderness areas in the county that are part of the National Wilderness Preservation System; this is the largest number of any county in the United States. The majority are managed by the Bureau of Land Management, but some are integral components of the above listed national protected areas. Most of these wilderness areas lie within the county, but a few are shared with neighboring counties. Except as noted, these wilderness areas are managed by the Bureau of Land Management and lie within San Bernardino County: The 2010 United States Census reported that San Bernardino County had a population of 2,035,210.
The racial makeup of San Bernardino County was 1,153,16
Geologic time scale
The geologic time scale is a system of chronological dating that relates geological strata to time. It is used by geologists and other Earth scientists to describe the timing and relationships of events that have occurred during Earth's history; the table of geologic time spans, presented here, agree with the nomenclature and standard color codes set forth by the International Commission on Stratigraphy. The primary defined divisions of time are eons, in sequence the Hadean, the Archean, the Proterozoic and the Phanerozoic; the first three of these can be referred to collectively as the Precambrian supereon. Eons are divided into eras, which are in turn divided into periods and ages; the following four timelines show the geologic time scale. The first shows the entire time from the formation of the Earth to the present, but this gives little space for the most recent eon. Therefore, the second timeline shows an expanded view of the most recent eon. In a similar way, the most recent era is expanded in the third timeline, the most recent period is expanded in the fourth timeline.
Corresponding to eons, periods and ages, the terms "eonothem", "erathem", "system", "series", "stage" are used to refer to the layers of rock that belong to these stretches of geologic time in Earth's history. Geologists qualify these units as "early", "mid", "late" when referring to time, "lower", "middle", "upper" when referring to the corresponding rocks. For example, the lower Jurassic Series in chronostratigraphy corresponds to the early Jurassic Epoch in geochronology; the adjectives are capitalized when the subdivision is formally recognized, lower case when not. Evidence from radiometric dating indicates; the geology or deep time of Earth's past has been organized into various units according to events which took place. Different spans of time on the GTS are marked by corresponding changes in the composition of strata which indicate major geological or paleontological events, such as mass extinctions. For example, the boundary between the Cretaceous period and the Paleogene period is defined by the Cretaceous–Paleogene extinction event, which marked the demise of the non-avian dinosaurs and many other groups of life.
Older time spans, which predate the reliable fossil record, are defined by their absolute age. Geologic units from the same time but different parts of the world look different and contain different fossils, so the same time-span was given different names in different locales. For example, in North America, the Lower Cambrian is called the Waucoban series, subdivided into zones based on succession of trilobites. In East Asia and Siberia, the same unit is split into Alexian and Botomian stages. A key aspect of the work of the International Commission on Stratigraphy is to reconcile this conflicting terminology and define universal horizons that can be used around the world; some other planets and moons in the Solar System have sufficiently rigid structures to have preserved records of their own histories, for example, Venus and the Earth's Moon. Dominantly fluid planets, such as the gas giants, do not preserve their history in a comparable manner. Apart from the Late Heavy Bombardment, events on other planets had little direct influence on the Earth, events on Earth had correspondingly little effect on those planets.
Construction of a time scale that links the planets is, therefore, of only limited relevance to the Earth's time scale, except in a Solar System context. The existence and terrestrial effects of the Late Heavy Bombardment are still debated. In Ancient Greece, Aristotle observed that fossils of seashells in rocks resembled those found on beaches – he inferred that the fossils in rocks were formed by organisms, he reasoned that the positions of land and sea had changed over long periods of time. Leonardo da Vinci concurred with Aristotle's interpretation that fossils represented the remains of ancient life; the 11th-century Persian geologist Avicenna and the 13th-century Dominican bishop Albertus Magnus extended Aristotle's explanation into a theory of a petrifying fluid. Avicenna first proposed one of the principles underlying geologic time scales, the law of superposition of strata, while discussing the origins of mountains in The Book of Healing; the Chinese naturalist Shen Kuo recognized the concept of "deep time".
In the late 17th century Nicholas Steno pronounced the principles underlying geologic time scales. Steno argued that rock layers were laid down in succession, that each represents a "slice" of time, he formulated the law of superposition, which states that any given stratum is older than those above it and younger than those below it. While Steno's principles were simple, applying them proved challenging. Steno's ideas lead to other important concepts geologists use today, such as relative dating. Over the course of the 18th century geologists realized that: Sequences of strata become eroded, tilted, or inverted after deposition Strata laid down at the same time in different areas could have different appearances The strata of any given area represented only part of Earth's long historyThe Neptunist theories popular at this time proposed that all rocks had precipitated out of a single enormous flood. A major shift in thinking came.
Cima volcanic field
Cima volcanic field is a volcanic field in San Bernardino County, close to the border with Nevada. The volcanic field covers a surface area of 600 square kilometres within the Mojave National Preserve west of the Cima Dome and consists of about 40 volcanic cones with about 60 lava flows; the volcanic cones range from simple cones over multi-cratered mountains to eroded hills, lava flows are up to 9.1 kilometres long. At least one lava tube can be visited. Volcanic activity in the field commenced in the Late Miocene and after a pause between 3 and 1 million years ago continued into the latest Pleistocene; the youngest cone is known as the Black Tank cone and formed about 15,000 years before present, although it is possible that it was formed through two separate eruption events. The Cima volcanic field lies in the eastern Mojave Desert of California, between the Shadow Valley in the northeast, the Cima Dome in the east and the Soda Lake Valley in the southwest. Southwest of the field is the Kelbaker Road which crosses some lava flows, dirt roads such as the Indian Springs Trail and the Aiken Mine Road crisscross between the volcanoes.
Interstate 15 passes north of the field and just south of older volcanic units, while California State Route 127 runs west and southwest of the field, The city of Las Vegas is 120 kilometres northeast of the area. The Cima volcanoes are part of the Mojave National Preserve and since 1973 they make up the Cinder Cones National Natural Landmark. During the Holocene and until recent times, humans engraved petroglyphs into the lava flows. One cinder cone was quarried to obtain materials for road construction; the volcanic field has been the subject of landscape development research. Volcanism occurs in various forms at various places. Among the better known are the Cascade volcanoes created by subduction off the western coast of North America, which include the caldera of Mount Mazama as well as stratovolcanoes such as Mount St. Helens and mafic volcanic fields. Other volcanic centres in the United States are those associated with Yellowstone Caldera and Snake River Plain, those along the margins of the Colorado Plateau, volcanoes linked to the Rio Grande Rift and Jemez lineament, volcanoes in the western Basin and Range Province such as the Cima volcanic field.
Volcanic activity was widespread in the dry regions of the western United States during the Tertiary and Quaternary, forming several volcanic fields. An earlier phase of felsic volcanism during the Tertiary was followed during the Quaternary by more basaltic volcanism in the form of short-lived volcanic vents. Examples of this kind of volcanism are the Cima volcanic field, the San Francisco volcanic field, the Southwest Nevada volcanic field and the Zuni-Bandera volcanic field; the Cima volcanic field is part of the Mojave Desert, which in turn belongs to the Basin and Range Province and features both mountains exceeding 2,000 metres height which trend in southeast-northwest direction, with broad valleys between the mountains. There are about 40 cones in the Cima volcanic field; the cones are as much as 890 metres wide and 170 metres high, they are concentrated between elevations of 1,400–790 metres on a south-southwest tilting slope. Some cones are well preserved with intact craters, while others have been reduced to hills by erosion.
Some cones have more than one crater. North of the main field lie two outcrops of older volcanic rocks. Several washes such as Willow Wash, Black Tank Wash and Indian Creek cross through the field and have eroded lava flows; the youngest cone in the southwestern part of the field is called Black Tank cone. The Black Tank cone is the source of a 2-kilometre long lava flow, which at first forms a levee-bound channel and narrows out into a lobate shape, it shows traces of a lava tube and has a volume of 0.015 cubic kilometres. This flow may have been preceded by a previous lava flow, buried by the main flow. An older vent lies just south-southwest of the Black Tank Cone; the field presents black and red volcanic rocks in the form of cinders, exposed feeder dykes and lava bombs, as well as agglutinates which are exposed in gullies and eroded vents. Bombs and cinders cover the less eroded cones, which are sometimes surrounded by base surge deposits. At some vents, tuff rings formed through phreatomagmatic activity.
Erosion has dug gullies and larger valleys in the older cones, including one 150-metre deep gorge. Volcanic material covers a surface area of about 150 square kilometres within an area of c. 600 square kilometres. The volcanic field was emplaced on a basement of Tertiary age, which comprises both crystalline bedrock and thick gravel deposits. Other rock formations in the area are of Proterozoic–Paleozoic to Mesozoic age, the region is considered to be part of the Ivanpah uplift; the cones have given rise to about 60 lava flows. Lava flows reach lengths of 9.1 kilometres, thicknesses of 2.5–4 metres and have surface features similar to pahoehoe or aa lava lava depending on how steep the slopes they flowed down were. The lava flows display structures like levees, finger-like and lobe-like edges at the lava flow margins and spires and material from the cones, rafted away by the lavas. One can distinguish betwee