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Hellhole
Hellhole is a large and deep pit cave in Germany Valley, eastern West Virginia. It is the 7th longest cave in the United States and is home to almost half of the world's population of Virginia big-eared bats. At 518 feet (158 meters), Hellhole is the deepest of several caves in the Valley. Hellhole has had a long and storied association with the National Speleological Society dating back to the creation of that organization in the early 1940s. Many basic caving techniques (e.g., the single rope technique) were developed in Hellhole's 154-foot (47 meter) entrance drop.
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  • 02 Nov 2022
Topic Review
Polar Forests of the Cretaceous
Cretaceous polar forests were temperate forests that grew at polar latitudes during the final period of the Mesozoic Era, known as the Cretaceous Period 145–66 Ma. During this period, global average temperature was about 10 °C (18 °F) higher and carbon dioxide (CO2) levels were approximately 1000 parts per million (ppm), 2.5 times the current concentration in Earth's atmosphere. The abundance of atmospheric carbon dioxide had a very significant impact on global climate and Earth's natural systems as its concentration is considered one of the main factors in the development of a pronounced greenhouse Earth during the Cretaceous with a very low average global temperature gradient. As a consequence, high paleolatitudes in both hemispheres were much warmer than at present. This temperature gradient was partly responsible for the lack of continental ice sheets in polar regions. As a response to elevated global temperatures, the Earth's hydrologic cycle was significantly enhanced due to greater volume of moisture evaporation from the surface of the ocean. In turn, the absolute sea level during this time period stood at elevations much higher than the present level. Continental encroachment of seawater formed widespread shallow seas, including expanses of epeiric seas. An increase in surface area between shallow, warm epeiric seawater and the atmosphere permits higher evaporation rates and more precipitation at various latitudes, producing a more temperate global climate. A widespread temperate climate also had significant effects on high latitude ecosystems.
  • 635
  • 02 Nov 2022
Topic Review
Weddell Island
Weddell Island (Spanish: Isla San José) is one of the Falkland Islands in the South Atlantic, lying off the southwest extremity of West Falkland. It is situated 1,545 km (960 mi) west-northwest of South Georgia Island, 1,165 km (724 mi) north of Livingston Island, 606 km (377 mi) northeast of Cape Horn, 358 km (222 mi) northeast of Isla de los Estados, and 510 km (320 mi) east of the Atlantic entrance to Magellan Strait. With an area of 265.8 km2 (102.6 sq mi) Weddell is the third largest island in the archipelago after East Falkland and West Falkland, and one of the largest private islands in the world. It has only one inhabited location, Weddell Settlement, with a single digit population engaged in sheep farming and tourism services. The island offers walks to wildlife watching sites and scenery destinations including some spectacular landscapes featuring the famous Falklands stone runs. Weddell is both an Important Plant Area and a priority Key Biodiversity Area. It is a remote place, infrequently visited by a resupply ship and occasionally by private yachts, accessible by air with a short (some 200 km (120 mi)) if expensive flight from the Falklands capital, Stanley.
  • 1.2K
  • 02 Nov 2022
Topic Review
Club of Rome
Founded in 1968 at Accademia dei Lincei in Rome, Italy, the Club of Rome consists of current and former heads of state, UN bureaucrats, high-level politicians and government officials, diplomats, scientists, economists, and business leaders from around the globe. It stimulated considerable public attention in 1972 with the first report to the Club of Rome, The Limits to Growth. Since 1 July 2008 the organization has been based in Winterthur, Switzerland.
  • 4.5K
  • 02 Nov 2022
Topic Review
Bauxite Tailings
Bauxite tailings, also known as bauxite residue, red mud, red sludge, or alumina refinery residues (ARR), is a highly alkaline waste product composed mainly of iron oxide that is generated in the industrial production of alumina (aluminium oxide, the principal raw material used in the manufacture of aluminium metal and also widely used in the manufacture of ceramics, abrasives and refractories). It is important to differentiate between the alkaline waste generated in the Bayer process and the tailings generated during the mining of bauxite. This article specifically covers the alkaline waste generated when operating the Bayer process. The scale of production makes the waste product an important one, and issues with its storage are reviewed and every opportunity is explored to find uses for it. Over 95% of the alumina produced globally is through the Bayer process; for every tonne of alumina produced, approximately 1 to 1.5 tonnes of bauxite tailings/residue are also produced. Annual production of alumina in 2018 was approximately 126 million tonnes resulting in the generation of over 160 million tonnes of bauxite tailings/residue.
  • 1.7K
  • 02 Nov 2022
Topic Review
Sirente Crater
The Sirente crater (Italian: Cratere del Sirente) is a small shallow seasonal lake in Abruzzo, central Italy. The depression, which is located at the center of the Prati del Sirente, a mountainous highland north of the Sirente massif in the Apennines, is 13 km (8.1 mi) from the village of Secinaro. Its formation has prompted a number of theories in recent years. Although in the absence of shock-metamorphic and / or geochemical evidence it is not yet possible to confirm the meteoritic impact theory, no other theories for the origin of this geological structure have been proven yet. Interest in the Sirente crater began in the late 1990s after Swedish geologist Jens Ormö, an impact crater specialist, noticed ridges near the site that indicated a bolide collision. A research team named "The Sirente Crater Group" along with two scientists from the International Research School of Planetary Science of Pescara (IRSPS) began a detailed examination of the area. The team concluded the meteorite struck the Earth with the force of a small nuclear bomb; approximately one kiloton in yield. The blast would have created a mushroom cloud and shockwaves similar to a nuclear explosion.
  • 610
  • 02 Nov 2022
Topic Review
Travertine
Travertine (/ˈtrævərˌtiːn/ TRA-vər-teen) is a form of limestone deposited by mineral springs, especially hot springs. Travertine often has a fibrous or concentric appearance and exists in white, tan, cream-colored, and even rusty varieties. It is formed by a process of rapid precipitation of calcium carbonate, often at the mouth of a hot spring or in a limestone cave. In the latter, it can form stalactites, stalagmites, and other speleothems. It is frequently used in Italy and elsewhere as a building material. Travertine is a terrestrial sedimentary rock, formed by the precipitation of carbonate minerals from solution in ground and surface waters, or geothermally heated hot-springs. Similar (but softer and extremely porous) deposits formed from ambient-temperature water are known as tufa.
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  • 02 Nov 2022
Topic Review
NOAAS Murre II
NOAAS Murre II (R 663), previously NOAAS Murre II (FRV 63), was an American research vessel in commission in the National Oceanic and Atmospheric Administration (NOAA) fleet from 1970 to 1989. Prior to her NOAA career, she operated under the United States Department of the Interior′s Fish and Wildlife Service from 1949 to 1956 and under the United States Fish and Wildlife Service′s Bureau of Commercial Fisheries from 1956 to 1970 as Murre II. The ship originally operated as a self-propelled barge, first as BSP-1915 for the United States Army during World War II and then for the Fish and Wildlife Service before undergoing conversion into a research ship in 1963.
  • 240
  • 02 Nov 2022
Topic Review
Level Mountain
Level Mountain is a large volcanic complex in the Northern Interior of British Columbia, Canada. It is located 50 kilometres (31 miles) north-northwest of Telegraph Creek and 60 kilometres (37 miles) west of Dease Lake on the Nahlin Plateau. With a maximum elevation of 2,164 metres (7,100 feet), it is the second-highest of four large complexes in an extensive north–south trending volcanic region. Much of the mountain is gently-sloping; when measured from its base, Level Mountain is about 1,100 metres (3,600 feet) tall, slightly taller than its neighbour to the northwest, Heart Peaks. The lower, broader half of Level Mountain consists of a shield-like structure while its upper half has a more steep, jagged profile. Its broad summit is dominated by the Level Mountain Range, a small mountain range with prominent peaks cut by deep valleys. These valleys serve as a radial drainage for several small streams that flow from the mountain. Meszah Peak is the only named peak in the Level Mountain Range. The mountain began forming about 15 million years ago, with volcanism having continued up until geologically recent times. There have been four stages of activity throughout the long volcanic history of Level Mountain. The first stage commenced 14.9 million years ago with the eruption of voluminous lava flows; these created a large shield volcano. The second stage began 7.1 million years ago to form a structurally complicated stratovolcano located centrally atop the shield. A series of lava domes was established during the third stage, which began 4.5 million years ago. This was followed by the fourth and final stage with the eruption of lava flows and small volcanic cones in the last 2.5 million years. A wide range of rock types were produced during these stages, namely ankaramites, alkali basalts, trachybasalts, mugearites, hawaiites, phonolites, trachytes and rhyolites. Alkali basalts and ankaramites are the most voluminous and comprise much of Level Mountain. The remaining rock types are less extensive and are largely restricted to the central region of the volcanic complex. Several types of volcanic eruptions produced these rocks. Level Mountain lies in one of many ecoregions encompassing British Columbia. It can be ecologically divided into three sections: lodgepole pine and white spruce forests at its base, bog birch and subalpine fir forests on its flanks, and an alpine climate at its summit. The extent and flatness of the alpine on Level Mountain have produced many Arctic affinities that are particularly noticeable in the local biota. Several animal species thrive in the area of Level Mountain, with caribou being the most abundant. A trading post was established at Level Mountain in the 1890s, followed by geological studies of the mountain from the 1920s onwards. This remote area of Cassiar Land District has a relatively dry environment compared to the Coast Mountains in the west. Due to its remoteness, Level Mountain can only be accessed by air or by trekking great distances on foot. The closest communities are more than 30 kilometres (19 miles) away from the mountain.
  • 549
  • 02 Nov 2022
Topic Review
Propagating Rifts
Propagating rifts are seafloor features associated with spreading centers at mid-ocean ridges and back-arc basins. They are more commonly observed on faster rate spreading centers (50 mm/year or more). These features are formed by the lengthening of one spreading segment at the expense of an offset neighboring spreading segment. Hence, these are remnant features produced by migration of the tip of a spreading center. In other words, as the tip of a spreading center migrates or grows, the plate itself grows at the expense of the shrinking plate, transferring lithosphere from the shrinking plate to the growing plate.
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  • 02 Nov 2022
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