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Hope Basin
The Hope Basin is a geological feature of the Chukchi Sea Shelf. It lies off the Chukchi Sea coast of Alaska. Its area extends from the outer continental shelf of the Seward Peninsula for about westwards off the coast of Chukotka towards Wrangel Island. The Hope Basin is limited on its northeastern side by the Herald Arch (Herald Thrust), a basement uplift cored by Cretaceous thrust faults. The Herald Arch is named after Herald Island. Type: Early Tertiary extensional In any of several fields of study that treat the use of signs — for example, in linguistics Linguistics is the science, scientific study of human language. It is called a scientific study because it entails a comprehensive, systematic, obj ... basin (mainly). References * * Marine geology Landforms of the Chukchi Sea {{regional-geology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chukchi Sea Shelf
The Chukchi Sea Shelf or Chukchi Shelf is the westernmost part of the continental shelf of the United States and the easternmost part of the continental shelf of Russia. Within this shelf, the 50-mile Chukchi Corridor acts as a passageway for one of the largest marine mammal migrations in the world. The main geological features of the Chukchi Shelf are the Hope Basin and the Herald Thrust, a basement uplift cored by Cretaceous thrust faults. The latter is named after Herald Island (Arctic), Herald Island. Off the northwestern Alaskan coast there is a Jurassic rift basin, the Hannah Trough. To the north of Alaska the Chukchi Shelf extends to form the Chukchi Plateau which protrudes into the Arctic Ocean geological zone. The Chukchi Shelf is shared between Russia and the United States according to the 1990 USSR–USA Maritime Boundary Agreement. 50-Mile Chukchi Corridor The Chukchi Corridor is a 50-mile wide strip of ocean offshore of Northwest Alaska that acts as a passageway for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chukchi Sea
Chukchi Sea ( rus, Чуко́тское мо́ре, r=Chukotskoye more, p=tɕʊˈkotskəjə ˈmorʲɪ), sometimes referred to as the Chuuk Sea, Chukotsk Sea or the Sea of Chukotsk, is a marginal sea of the Arctic Ocean. It is bounded on the west by the Long Strait, off Wrangel Island, and in the east by Point Barrow, Alaska, beyond which lies the Beaufort Sea. The Bering Strait forms its southernmost limit and connects it to the Bering Sea and the Pacific Ocean. The principal port on the Chukchi Sea is Uelen in Russia. The International Date Line crosses the Chukchi Sea from northwest to southeast. It is displaced eastwards to avoid Wrangel Island as well as the Chukotka Autonomous Okrug on the Russian mainland. Geography The sea has an approximate area of and is only navigable about four months of the year. The main geological feature of the Chukchi Sea bottom is the Hope Basin, which is bound to the northeast by the Herald Arch. Depths less than occupy 56% of the total ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alaska
Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., it borders the Canadian province of British Columbia and the Yukon territory to the east; it also shares a maritime border with the Russian Federation's Chukotka Autonomous Okrug to the west, just across the Bering Strait. To the north are the Chukchi and Beaufort Seas of the Arctic Ocean, while the Pacific Ocean lies to the south and southwest. Alaska is by far the largest U.S. state by area, comprising more total area than the next three largest states (Texas, California, and Montana) combined. It represents the seventh-largest subnational division in the world. It is the third-least populous and the most sparsely populated state, but by far the continent's most populous territory located mostly north of the 60th parallel, with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Continental Shelf
A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island is known as an ''insular shelf''. The continental margin, between the continental shelf and the abyssal plain, comprises a steep continental slope, surrounded by the flatter continental rise, in which sediment from the continent above cascades down the slope and accumulates as a pile of sediment at the base of the slope. Extending as far as 500 km (310 mi) from the slope, it consists of thick sediments deposited by turbidity currents from the shelf and slope. The continental rise's gradient is intermediate between the gradients of the slope and the shelf. Under the United Nations Convention on the Law of the Sea, the name continental shelf was given a legal definition as the stretch of the seabed adjacent to the shores of a par ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seward Peninsula
The Seward Peninsula is a large peninsula on the western coast of the U.S. state of Alaska whose westernmost point is Cape Prince of Wales. The peninsula projects about into the Bering Sea between Norton Sound, the Bering Strait, the Chukchi Sea, and Kotzebue Sound, just below the Arctic Circle. The entire peninsula is about long and wide. Like Seward, Alaska, it was named after William H. Seward, the United States Secretary of State who fought for the U.S. purchase of Alaska. The Seward Peninsula is a remnant of the Bering land bridge, a roughly thousand mile wide swath of land connecting Siberia with mainland Alaska during the Pleistocene Ice Age. This land bridge aided in the migration of humans, as well as plant and animal species, from Asia to North America. Excavations at sites such as the Trail Creek Caves and Cape Espenberg in the Bering Land Bridge National Preserve as well as Cape Denbigh to the south have provided insight into the timeline of prehistorical migrat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chukotka Autonomous Okrug
Chukotka (russian: Чуко́тка), officially the Chukotka Autonomous Okrug,, ''Čukotkakèn avtonomnykèn okrug'', is the easternmost federal subjects of Russia, federal subject of Russia. It is an autonomous okrug situated in the Russian Far East, and shares a border with the Sakha, Sakha Republic to the west, Magadan Oblast to the south-west, and Kamchatka Krai to the south. Anadyr (town), Anadyr is the largest types of inhabited localities in Russia, town and the administrative center, capital, and the easternmost settlement to have town status in Russia. Chukotka is primarily populated by ethnic Russians, Chukchi people, Chukchi, and other Indigenous peoples of Siberia, indigenous peoples. It is the only autonomous okrug in Russia that is not included in, or subordinate to, another federal subject, having separated from Magadan Oblast in 1992. It is home to Lake Elgygytgyn, an impact crater lake, and Anyuyskiy, an extinct volcano. The village of Uelen is the easternmos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wrangel Island
Wrangel Island ( rus, О́стров Вра́нгеля, r=Ostrov Vrangelya, p=ˈostrəf ˈvrangʲɪlʲə; ckt, Умӄиԓир, translit=Umqiḷir) is an island of the Chukotka Autonomous Okrug, Russia. It is the 91st largest island in the world and roughly the size of Crete. Located in the Arctic Ocean between the Chukchi Sea and East Siberian Sea, the island lies astride the 180th meridian. The International Date Line is therefore displaced eastwards at this latitude to avoid the island as well as the Chukchi Peninsula on the Russian mainland, to keep the island on the same day as the rest of Russia. The closest land to Wrangel Island is the tiny and rocky Herald Island located to the east.Kosko, M.K., M.P. Cecile, J.C. Harrison, V.G. Ganelin, N.V., Khandoshko, and B.G. Lopatin, 1993Geology of Wrangel Island, Between Chukchi and East Siberian Seas, Northeastern Russia.Bulletin 461, Geological Survey of Canada, Ottawa Ontario, 101 pp. Wrangel Island is the last known pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin ''creta'', "chalk", which is abundant in the latter half of the period. It is usually abbreviated K, for its German translation ''Kreide''. The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now- extinct marine reptiles, ammonites, and rudists, while dinosaurs continued to dominate on land. The world was ice free, and forests extended to the poles. During this time, new groups of mammals and birds appeared. During the Early Cretaceous, flowering plants appeared and began to rapidly diversify, becoming the dominant group of plants across the Earth b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thrust Fault
A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If the angle of the fault plane is lower (often less than 15 degrees from the horizontal) and the displacement of the overlying block is large (often in the kilometer range) the fault is called an ''overthrust'' or ''overthrust fault''. Erosion can remove part of the overlying block, creating a ''fenster'' (or ''window'') – when the underlying block is exposed only in a relatively small area. When erosion removes most of the overlying block, leaving island-like remnants resting on the lower block, the remnants are called ''klippen'' (singular ''klippe''). Blind thrust faults If the fault plane terminates before it reaches the Earth's surface, it is referred to as a ''blind thrust'' fault. Because of the lack of surface evidence, blind thr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herald Island (Arctic)
Herald Island (russian: Остров Геральд, ''Ostrov Gerald'') is a small, isolated Russian island in the Chukchi Sea, east of Waring Point, Wrangel Island. It rises in sheer cliffs, making it quite inaccessible, either by ship or by plane. The only bit of accessible shoreline is at its northwestern point, where the cliffs have crumbled into piles of loose rocks and gravel. Its area is and the maximum height above sea level is . The island is unglaciated and uninhabited. Herald Island belongs administratively to the Chukotka Autonomous Okrug of the Russian Federation. Along with Wrangel Island, Herald Island is part of the Wrangel Island Wildlife Preserve, a Russian National Park, since 1976. Cape Dmitrieva on Herald Island, marks the easternmost limits of the nature reserve. Herald Island is named after survey vessel HMS ''Herald'', from which the island was discovered in 1849. Geology Herald Island is composed of sedimentary, metamorphic, and igneous rocks. The no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tertiary
Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start of the Cenozoic Era, and extended to the beginning of the Quaternary glaciation at the end of the Pliocene Epoch. The time span covered by the Tertiary has no exact equivalent in the current geologic time system, but it is essentially the merged Paleogene and Neogene periods, which are informally called the Early Tertiary and the Late Tertiary, respectively. The Tertiary established the Antarctic as an icy island continent. Historical use of the term The term Tertiary was first used by Giovanni Arduino during the mid-18th century. He classified geologic time into primitive (or primary), secondary, and tertiary periods based on observations of geology in Northern Italy. Later a fourth period, the Quaternary, was applied. In the early d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extensional Tectonics
Extensional tectonics is concerned with the structures formed by, and the tectonic processes associated with, the stretching of a planetary body's crust or lithosphere. Deformation styles The types of structure and the geometries formed depend on the amount of stretching involved. Stretching is generally measured using the parameter ''β'', known as the ''beta factor'', where : \beta = \frac \,, ''t''0 is the initial crustal thickness and ''t''1 is the final crustal thickness. It is also the equivalent of the strain parameter ''stretch''. Low beta factor In areas of relatively low crustal stretching, the dominant structures are high to moderate angle normal faults, with associated half grabens and tilted fault blocks. High beta factor In areas of high crustal stretching, individual extensional faults may become rotated to too low a dip to remain active and a new set of faults may be generated. Large displacements may juxtapose syntectonic sediments against metamorphic roc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
