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The Geology of Bangladesh is affected by the country's location, as Bangladesh is mainly a riverine country. It is the eastern two-thirds of the Ganges and Brahmaputra river delta plain stretching to the north from the Bay of Bengal. There are two small areas of slightly higher land in the north-centre and north-west composed of old alluvium called the Madhupur Tract and the Barind Tract, and steep, folded, hill ranges of older (Tertiary) rocks along the eastern border.
The geology of Tasmania is complex, with the world's biggest exposure of diabase, or dolerite. The rock record contains representatives of each period of the Neoproterozoic, Paleozoic, Mesozoic and Cenozoic eras. It is one of the few southern hemisphere areas that were glaciated during the Pleistocene with glacial landforms in the higher parts. The west coast region hosts significant mineralisation and numerous active and historic mines.
Simi Valley is a synclinal valley in Southern California in the United States. It is an enclosed or hidden valley surrounded by mountains and hills. It is connected to the San Fernando Valley to the east by the Santa Susana Pass and the 118 freeway, and in the west the narrows of the Arroyo Simi and the Reagan Freeway connection to Moorpark. The relatively flat bottom of the valley contains soils formed from shales, sandstones, and conglomerates eroded from the surrounding hills of the Santa Susana Mountains to the north, which separate Simi Valley from the Santa Clara River Valley, and the Simi Hills.
The Caballo Mountains, are a mountain range located in Sierra and Doña Ana Counties, New Mexico, United States. The range is located east of the Rio Grande and Caballo Lake, and west of the Jornada del Muerto; the south of the range extends into northwest Doña Ana County. The nearest towns are Truth or Consequences and Hatch.
The island of Taiwan was formed approximately 4 to 5 million years ago at a convergent boundary between the Philippine Sea Plate and the Eurasian Plate. In a boundary running the length of the island and continuing southwards, the Eurasian Plate is sliding under the Philippine Sea Plate. In the northeast of the island, the Philippine Sea Plate slides under the Eurasian Plate. Most of the island comprises a huge fault block tilted to the west.
The Semilir eruption was a major volcanic event which took place in Indonesia during the Early Miocene. This eruption formed the Semilir Formation and Nglanngran Formation. These two geological formations are in the Southern Mountains of East Java. The eruption created two formations which consist of mostly pyroclastic rock. It has incredible thickness. In contrast, The Toba supereruption only formed 600 m (2,000 ft) ignimbrite. The estimated Semilir eruption age date by isotope method is 21 million years ago.
The island of Bonaire began to form as part of the Lesser Antilles island arc in the past 145 million years, beginning in the Cretaceous. The island has been submerged or partially submerged for much of its existence, forming large limestone and sedimentary rock formations, atop a thick basement of volcanic rocks.
The island of Curaçao began to form within the past 145 million years, beginning in the Cretaceous, as part of the Lesser Antilles island arc. Because the island was submerged for large parts of its history, reef environments formed atop thick layers of mafic volcanic rock, producing carbonate sedimentary rocks.
The geology of Guam formed as a result of mafic, felsic and intermediate composition volcanic rocks erupting below the ocean, building up the base of the island in the Eocene, between 33.9 and 56 million years ago. The island emerged above the water in the Eocene, although the volcanic crater collapsed. A second volcanic crater formed on the south of the island in the Oligocene and Miocene. In the shallow water, numerous limestone formations took shape, with thick alternating layers of volcanic material. The second crater collapsed and Guam went through a period in which it was almost entirely submerged, resembling a swampy atoll, until structural deformation slowly uplifted different parts of the island to their present topography. The process of uplift led to widespread erosion and clay formation, as well as the deposition of different types of limestone, reflecting different water depths.
The geology of Georgia is the study of rocks, minerals, water, landforms and geologic history in Georgia. The country is dominated by the Caucasus Mountains at the junction of the Eurasian Plate and the Afro-Arabian Plate, and rock units from the Mesozoic and Cenozoic are particularly prevalent. For much of its geologic history, until the uplift of the Caucasus, Georgia was submerged by marine transgression events. Geologic research for 150 years by Georgian and Russian geologists has shed significant light on the region and since the 1970s has been augmented with the understanding of plate tectonics.
The geology of Bosnia & Herzegovina is the study of rocks, minerals, water, landforms and geologic history in the country. The oldest rocks exposed at or near the surface date to the Paleozoic and the Precambrian geologic history of the region remains poorly understood. Complex assemblages of flysch, ophiolite, mélange and igneous plutons together with thick sedimentary units are a defining characteristic of the Dinaric Alps, also known as the Dinaride Mountains, which dominate much of the country's landscape.
The geology of the U.S. Virgin Islands includes mafic volcanic rocks, with complex mineralogy that first began to erupt in the Mesozoic overlain and interspersed with carbonate and conglomerate units.
The geology of Alaska includes Precambrian igneous and metamorphic rocks formed in offshore terranes and added to the western margin of North America from the Paleozoic through modern times. The region was submerged for much of the Paleozoic and Mesozoic and formed extensive oil and gas reserves due to tectonic activity in the Arctic Ocean. Alaska was largely ice free during the Pleistocene, allowing humans to migrate into the Americas.
The geology of Uzbekistan consists of two microcontinents and the remnants of oceanic crust, which fused together into a tectonically complex but resource rich land mass during the Paleozoic, before becoming draped in thick, primarily marine sedimentary units.
The geology of Greece is highly structurally complex due to its position at the junction between the European and African tectonic plates.
The geology of Trinidad and Tobago includes two different islands with different geological histories.
The geology of Yukon includes sections of ancient Precambrian Proterozoic rock from the western edge of the proto-North American continent Laurentia, with several different island arc terranes added through the Paleozoic, Mesozoic and Cenozoic, driving volcanism, pluton formation and sedimentation.
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.
The Vasquez Formation (Tvz) is a geologic formation cropping out at the eponymous Vasquez Rocks in southern California. The formation dates to the Late Oligocene to Early Miocene.
The Ryukyu Arc is an island arc which extends from the south of Kyushu along the Ryukyu Islands to the northeast of Taiwan, spanning about 1,200 kilometres (750 mi). It is located along a section of the convergent plate boundary where the Philippine Sea Plate is subducting northwestward beneath the Eurasian Plate along the Ryukyu Trench. The arc has an overall northeast to southwest trend and is located northwest of the Pacific Ocean and southeast of the East China Sea. It runs parallel to the Okinawa Trough, an active volcanic arc, and the Ryukyu Trench. The Ryukyu Arc, based on its geomorphology, can be segmented from north to south into Northern Ryukyu, Central Ryukyu, and Southern Ryukyu; the Tokara Strait separates Northern Ryukyu and Central Ryukyu at about 130˚E while the Kerama Gap separates Central Ryukyu and Southern Ryukyu at about 127 ˚E. The geological units of the arc include igneous, sedimentary, and metamorphic rocks, ranging from the Paleozoic to Cenozoic in age.
References
- ↑ Weary, David J.; Burton, William C. (2011). "Preliminary geologic map of the island of Saipan, Commonwealth of the Northern Mariana Islands". Open-File Report. doi:10.3133/ofr20111234.