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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 renowned for its dramatic cliffs, drawing tourists to the region. It is often likened to a maze due to its inverted S-shape, where both the entrance and exits feature sharp bends, creating a challenging and scenic navigational experience. Geology The Neumayer Channel Tectonic block, 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 ... [...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. The term ''granodiorite'' was first used by George F. Becker, G. F. Becker (1893) to describe granitic rocks in the Sierra Nevada, United States. 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 composition, intermediate in composition. It is the Intrusive rock, 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 miner ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Straits Of The Palmer Archipelago
A strait is a water body connecting two seas or water basins. The surface water is, for the most part, at the same elevation on both sides and flows through the strait in both directions, even though the topography generally constricts the flow somewhat. In some straits there is a dominant directional current. Most commonly, the strait is a narrowing channel that lies between two land masses. Straits are loci for sediment accumulation, with sand-size deposits usually occurring on the two strait exits, forming subaqueous fans or deltas. Some straits are not navigable because, for example, they are too narrow or too shallow, or because of an unnavigable reef or archipelago. 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. ... [...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 Palmer Archipelago, also known as Antarctic Archipelago, Archipiélago Palmer, Antarktiske Arkipel or Palmer Inseln, is a group of islands off the northwestern coast of the Antarctic Peninsula. It extends from Tower Island in the north to Anvers ..., Antarctica. It was charted from 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 (1900) formally named ''Belgica antarctica'' by the Belgian Entomology, entomologist Jean-Charles Jacobs. The Gerlache Strait has spiky blue icebergs, and is frequented by whales. It can be viewed from Spigot Peak. Geology Four tectonic blocks are identifiable in the Gerlache Strait area, bounded by two systems of Tertiary period, Tertiary strike-slip faults. The longitudinal faults include the SW-NE trending Neumayer Fault that extends fr ... [...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''). A pyroclastic rock containing 25–75% volcanic bombs or volcanic blocks is called tuff breccia. 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 t ... [...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 Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fracture in the Crust (geology), crust, on land or underwater, usually at temperatures from . The volcanic rock resulting from subsequent cooling is often also 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. Etymology The word ''lava'' comes from Ital ... [...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 (VEI-4), which disrupted European and transatlantic air travel from 15-20 April 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 diagram. ... [...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 s ... [...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)
In geology, a dike or dyke is a sheet of rock that is formed in a fracture of a pre-existing rock body. Dikes can be either magmatic or 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) reaches the surface. They are studied by geologists for the clues they ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Tertiary
The Neogene ( ,) is a Geologic time scale#Terminology, geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago (Year#Abbreviations yr and ya, Mya) to the beginning of the present Quaternary Period million years ago. It is the second period of the Cenozoic and the eleventh period of the Phanerozoic. The Neogene is sub-divided into two Epoch (geology), 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 Hoernes, Moritz Hörnes (1815–1868). The earlier term Tertiary (period), Tertiary Period was used to define the span of time now covered by Paleogene and Neogene and, despite no longer being recognized as a formal stratigraphy, stratigraphic term, "Tertiary" still sometimes remains in informal use. During this period, mammals an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
