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Neumayer Channel
Neumayer Channel () is a channel 16 miles (26 km) long in a NE-SW direction and about 1.5 miles (2.4 km) wide, separating Anvers Island from Wiencke Island and Doumer Island, in the Palmer Archipelago. The southwest entrance to this channel was seen by Eduard Dallmann, leader of the German 1873-74 expedition, who named it Roosen Channel. The Belgian Antarctic Expedition, 1897–99, under Gerlache, sailed through the channel and named it for Georg von Neumayer. The second name has been approved because of more general usage. Neumayer Channel is known for its majestic cliffs, an attraction for tourists who come to the region. It is said to be like a maze with no visible exits because of its inverted S-shape. Its entrance and exits both have sharp bends. Geology The Neumayer Channel Tectonic Block is bounded by the Neumayer Fault and the Fournier Fault, which are parallel SW-NE trending strike-slip faults. The block consists of an Early Tertiary granite- granodior ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neumayer Channel
Neumayer Channel () is a channel 16 miles (26 km) long in a NE-SW direction and about 1.5 miles (2.4 km) wide, separating Anvers Island from Wiencke Island and Doumer Island, in the Palmer Archipelago. The southwest entrance to this channel was seen by Eduard Dallmann, leader of the German 1873-74 expedition, who named it Roosen Channel. The Belgian Antarctic Expedition, 1897–99, under Gerlache, sailed through the channel and named it for Georg von Neumayer. The second name has been approved because of more general usage. Neumayer Channel is known for its majestic cliffs, an attraction for tourists who come to the region. It is said to be like a maze with no visible exits because of its inverted S-shape. Its entrance and exits both have sharp bends. Geology The Neumayer Channel Tectonic Block is bounded by the Neumayer Fault and the Fournier Fault, which are parallel SW-NE trending strike-slip faults. The block consists of an Early Tertiary granite- granodior ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Granodiorite
Granodiorite () is a coarse-grained (phaneritic) intrusive igneous rock similar to granite, but containing more plagioclase feldspar than orthoclase feldspar. The term banatite is sometimes used informally for various rocks ranging from granite to diorite, including granodiorite. Composition According to the QAPF diagram, granodiorite has a greater than 20% quartz by volume, and between 65% and 90% of the feldspar is plagioclase. A greater amount of plagioclase would designate the rock as tonalite. Granodiorite is felsic to intermediate in composition. It is the intrusive igneous equivalent of the extrusive igneous dacite. It contains a large amount of sodium (Na) and calcium (Ca) rich plagioclase, potassium feldspar, quartz, and minor amounts of muscovite mica as the lighter colored mineral components. Biotite and amphiboles often in the form of hornblende are more abundant in granodiorite than in granite, giving it a more distinct two-toned or overall darker appearan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Straits Of The Palmer Archipelago
A strait is an oceanic landform connecting two seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either direction. Most commonly, it is a narrow ocean channel that lies between two land masses. Some straits are not navigable, for example because they are either too narrow or too shallow, or because of an unnavigable reef or archipelago. Straits are also known to be loci for sediment accumulation. Usually, sand-size deposits occur on both the two opposite strait exits, forming subaqueous fans or deltas. Terminology The terms ''channel'', ''pass'', or ''passage'' can be synonymous and used interchangeably with ''strait'', although each is sometimes differentiated with varying senses. In Scotland, ''firth'' or ''Kyle'' are also sometimes used as synonyms for strait. Many straits are economically important. Straits can be important shipping routes and wars have been fought for control of them. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Green Reef
Green Reef () is a group of low rocks in Neumayer Channel, lying close east of Green Spur, Anvers Island, in the Palmer Archipelago, Antarctica. It was charted from HMS Snipe (U20), HMS ''Snipe'' in January 1948 and so named because of its proximity to Green Spur. References Reefs of Graham Land Landforms of the Palmer Archipelago {{PalmerArchipelago-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gerlache Strait
Gerlache Strait or de Gerlache Strait or Détroit de la Belgica is a Channel (geography), channel/strait separating the Palmer Archipelago from the Antarctic Peninsula. The Belgian Antarctic Expedition, under Lt. Adrien de Gerlache, explored the strait in January and February 1898, naming it for the expedition ship ''RV Belgica (1884), Belgica''. The name was later changed to honor the commander himself. On the expedition in the Gerlache Strait, biologist Emil Racoviță made several discoveries, including a flightless midge fly that was later formally named ''Belgica antarctica'' by the Belgian Entomology, entomologist Jean-Charles Jacobs. Geology Four tectonic blocks are identifiable in the Gerlache Strait area, bounded by two systems of Tertiary strike-slip faults. The longitudinal faults include the SW-NE trending Neumayer Fault that extends from Peltier Channel across Wiencke Island, and then onwards most likely as the Gerlache Fault. The SW-NE trending Fournier Fault paral ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuff
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock containing 25% to 75% ash is described as tuffaceous (for example, ''tuffaceous sandstone''). Tuff composed of sandy volcanic material can be referred to as volcanic sandstone. Tuff is a relatively soft rock, so it has been used for construction since ancient times. Because it is common in Italy, the Romans used it often for construction. The Rapa Nui people used it to make most of the ''moai'' statues on Easter Island. Tuff can be classified as either igneous or sedimentary rock. It is usually studied in the context of igneous petrology, although it is sometimes described using sedimentological terms. Tuff is often erroneously called tufa in guidebooks and in television programmes. Volcanic ash The material that is expelled in a volcanic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lava
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or underwater, usually at temperatures from . The volcanic rock resulting from subsequent cooling is also often called ''lava''. A lava flow is an outpouring of lava during an effusive eruption. (An explosive eruption, by contrast, produces a mixture of volcanic ash and other fragments called tephra, not lava flows.) The viscosity of most lava is about that of ketchup, roughly 10,000 to 100,000 times that of water. Even so, lava can flow great distances before cooling causes it to solidify, because lava exposed to air quickly develops a solid crust that insulates the remaining liquid lava, helping to keep it hot and inviscid enough to continue flowing. The word ''lava'' comes from Italian and is probably derived from the Latin word ''labes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trachyandesitic
Trachyandesite is an extrusive igneous rock with a composition between trachyte and andesite. It has little or no free quartz, but is dominated by sodic plagioclase and alkali feldspar. It is formed from the cooling of lava enriched in alkali metals and with an intermediate content of silica. The term ''trachyandesite'' had begun to fall into disfavor by 1985 but was revived to describe extrusive igneous rocks falling into the S3 field of the TAS classification. These are divided into sodium-rich benmoreite and potassium-rich latite. Trachyandesitic magma can produce explosive Plinian eruptions, such as happened at Tambora in 1815. The Eyjafjallajökull 2010 eruption (VEI4), which disrupted European and transatlantic air travel from 14–18 October 2010, for some time was dominated by trachyandesite. Petrology Trachyandesite is characterized by a silica content near 58% and a total alkali oxide content near 9%. This places trachyandesite in the S3 field of the TAS diagr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basaltic
Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example, the bulk of the plains of Venus, which cover ~80% of the surface, are basaltic; the lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars. Molten basalt lava has a low viscosity due to its relatively low silica content (between 45% and 52%), resulting in rapidly moving lava flows that can spread over great areas before cooling and solidifying. Flood basalts are thick sequence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intrusive Rock
Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form ''Igneous intrusion, intrusions'', such as batholiths, dike (geology), dikes, Sill (geology), sills, laccoliths, and volcanic necks.Intrusive RocksIntrusive rocks accessdate: March 27, 2017.Igneous intrusive rocks, accessdate: March 27, 2017.Britannica.comintrusive rock , geology , Britannica.com accessdate: March 27, 2017. Intrusion is one of the two ways igneous rock can form. The other is extrusive rock, extrusion, such as a Types of volcanic eruptions, volcanic eruption or similar event. An intrusion is any body of intrusive igneous rock, formed from magma that cools and solidifies within the crust of the planet. In contrast, an ''extrusion'' consists of extrusive rock, formed above the surface of the crust. Some geologists use the term plutonic rock synonymously with intrusive rock, but other geologists subdivide intrusive rock, by crystal size, into coarse-grai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dike (geology)
A dike or dyke, in Geology, geological usage, is a sheet of rock that is formed in a Fracture (geology), fracture of a pre-existing rock body. Dikes can be either Intrusive rock, magmatic or Sedimentary rock, sedimentary in origin. Magmatic dikes form when magma flows into a crack then solidifies as a sheet intrusion, either cutting across layers of rock or through a contiguous mass of rock. Clastic dikes are formed when sediment fills a pre-existing crack.Essentials of Geology, 3rd Ed, Stephen Marshak Magmatic dikes A magmatic dike is a sheet of igneous rock that cuts across older rock beds. It is formed when magma fills a fracture in the older beds and then cools and solidifies. The dike rock is usually more resistant to weathering than the surrounding rock, so that erosion exposes the dike as a natural wall or ridge. It is from these natural walls that dikes get their name. Dikes preserve a record of the fissures through which most mafic magma (fluid magma low in silica) reac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Tertiary
The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period Mya. The Neogene is sub-divided into two epochs, the earlier Miocene and the later Pliocene. Some geologists assert that the Neogene cannot be clearly delineated from the modern geological period, the Quaternary. The term "Neogene" was coined in 1853 by the Austrian palaeontologist Moritz Hörnes (1815–1868). During this period, mammals and birds continued to evolve into modern forms, while other groups of life remained relatively unchanged. The first humans (''Homo habilis'') appeared in Africa near the end of the period. Some continental movements took place, the most significant event being the connection of North and South America at the Isthmus of Panama, late in the Pliocene. This cut off the warm ocean currents from the Pacific to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
