Kentland Crater
The Kentland structure, also known as the Kentland crater or the Kentland disturbed area, is an impact structure located near the town of Kentland in Newton County, Indiana, United States. It was discovered about 1880 when two farmers began to quarry crushed rock there. The presence of shatter cones and deformed bedrock led geologists to conclude by the late 1960s that the Kentland structure is a deeply eroded impact structure, rather than volcanic in origin. Deformation at the site is so great that vertical contacts between normally horizontal rock formations of different ages are common. The structure itself is a circular dome, about in diameter, deeply eroded and buried in glacial debris. Its age is estimated to be less than 97 million years (Cretaceous or younger). The Shakopee dolomite at the center of the structure is about 450 million years old (Ordovician period) and is uplifted about 2,000 feet higher than the level of the same rock in the surrounding area. The entire ...
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Kentland IN Rock Deformation
Kentland may refer to a location in the United States: *Kentland, Indiana, in Newton County **Kentland crater ** Kentland Municipal Airport *Kentland, Maryland, in Prince George's County * Kentland Farm Historic and Archeological District near Blacksburg, Virginia ;See also * Kent Land District, Tasmania * Kent Land District, Western Australia *Kentlands, a neighborhood of Gaithersburg, Maryland Gaithersburg ( ), officially the City of Gaithersburg, is a city in Montgomery County, Maryland, United States. At the time of the 2020 U.S. Census, Gaithersburg had a population of 69,657, making it the ninth-largest location in the state. Gai ...

Apatite
Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH−, F− and Cl− ions, respectively, in the crystal. The formula of the admixture of the three most common endmembers is written as Ca10( PO4)6(OH,F,Cl)2, and the crystal unit cell formulae of the individual minerals are written as Ca10(PO4)6(OH)2, Ca10(PO4)6F2 and Ca10(PO4)6Cl2. The mineral was named apatite by the German geologist Abraham Gottlob Werner in 1786, although the specific mineral he had described was reclassified as fluorapatite in 1860 by the German mineralogist Karl Friedrich August Rammelsberg. Apatite is often mistaken for other minerals. This tendency is reflected in the mineral's name, which is derived from the Greek word ἀπατάω (apatáō), which means ''to deceive''. Geology Apatite is very common as an accessory mineral in igneous and metamorphic rocks, where it is the most common phosphate mineral. However, occu ...
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Shale
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite.Blatt, Harvey and Robert J. Tracy (1996) ''Petrology: Igneous, Sedimentary and Metamorphic'', 2nd ed., Freeman, pp. 281–292 Shale is characterized by its tendency to split into thin layers ( laminae) less than one centimeter in thickness. This property is called '' fissility''. Shale is the most common sedimentary rock. The term ''shale'' is sometimes applied more broadly, as essentially a synonym for mudrock, rather than in the more narrow sense of clay-rich fissile mudrock. Texture Shale typically exhibits varying degrees of fissility. Because of the parallel orientation of clay mineral flakes in shale, it breaks into thin layers, often splintery and usually parallel to the otherwise indistinguishable beddin ...
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Limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. About 20% to 25% of sedimentary rock is carbonate rock, and most of this is limestone. The remaining carbonate rock is mostly dolomite, a closely related rock, which contains a high percentage of the mineral dolomite, . ''Magnesian limestone'' is an obsolete and poorly-defined term used variously for dolomite, for limes ...
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Dolomite (rock)
Dolomite (also known as dolomite rock, dolostone or dolomitic rock) is a sedimentary carbonate rock that contains a high percentage of the mineral dolomite, CaMg(CO3)2. It occurs widely, often in association with limestone and evaporites, though it is less abundant than limestone and rare in Cenozoic rock beds (beds less than about 66 million years in age). The first geologist to distinguish dolomite rock from limestone was Belsazar Hacquet in 1778. Most dolomite was formed as a magnesium replacement of limestone or of lime mud before lithification. The geological process of conversion of calcite to dolomite is known as dolomitization and any intermediate product is known as dolomitic limestone. The "dolomite problem" refers to the vast worldwide depositions of dolomite in the past geologic record in contrast to the limited amounts of dolomite formed in modern times. Recent research has revealed sulfate-reducing bacteria living in anoxic conditions precipitate dolomite which ind ...
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Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozoic Era. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out. One important event in this period was the initial establishment of terrestrial life in what is known as the Silurian-Devonian Terrestrial Revolution: vascular plants emerged from more primitive land plants, dikaryan fungi started expanding and diversifying along with glomeromycotan fungi, and three groups of arthropods (myriapods, arachnids and hexapods) became fully terrestrialized. A significant evolutionary milestone during ...
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Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, where rocks from this period were first studied. The first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. The arthropod groups of myriapods, arachnids and hexapods also became well-established early in this period, after starting their expansion to land at least from the Ordovician period. Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the Age of Fishes. The placoderms began dominating ...
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Mississippian Age
The Mississippian ( , also known as Lower Carboniferous or Early Carboniferous) is a subperiod in the geologic timescale or a subsystem of the geologic record. It is the earlier of two subperiods of the Carboniferous period lasting from roughly 358.9 to 323.2 million years ago. As with most other geochronologic units, the rock beds that define the Mississippian are well identified, but the exact start and end dates are uncertain by a few million years. The Mississippian is so named because rocks with this age are exposed in the Mississippi Valley. The Mississippian was a period of marine transgression in the Northern Hemisphere: the sea level was so high that only the Fennoscandian Shield and the Laurentian Shield were dry land. The cratons were surrounded by extensive delta systems and lagoons, and carbonate sedimentation on the surrounding continental platforms, covered by shallow seas. In North America, where the interval consists primarily of marine limestones, it is treate ...
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Illinois Basin
The Illinois Basin is a Paleozoic depositional and structural basin in the United States, centered in and underlying most of the state of Illinois, and extending into southwestern Indiana and western Kentucky. The basin is elongate, extending approximately northwest-southeast, and southwest-northeast. Boundaries and sedimentary rocks The basin is bordered on the northeast by the Kankakee Arch, on the southeast by the Cincinnati Arch, on the south by the Pascola Arch, on the southwest by the Ozark Dome, on the northwest by the Mississippi River Arch, and on the north by the Wisconsin Arch. The New Madrid Seismic Zone and the Wabash Valley Seismic Zone intersect the southern portion of the basin. The major structural features within the basin include the La Salle anticlinal belt, the DuQuoin monocline, the Cottage Grove fault system, and the Fairfield Basin. At its center beneath southern Illinois, the basin contains a thickness of about 15,000 feet of Cambrian throug ...
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Indiana
Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th state on December 11, 1816. It is bordered by Lake Michigan to the northwest, Michigan to the north, Ohio to the east, the Ohio River and Kentucky to the south and southeast, and the Wabash River and Illinois to the west. Various indigenous peoples inhabited what would become Indiana for thousands of years, some of whom the U.S. government expelled between 1800 and 1836. Indiana received its name because the state was largely possessed by native tribes even after it was granted statehood. Since then, settlement patterns in Indiana have reflected regional cultural segmentation present in the Eastern United States; the state's northernmost tier was settled primarily by people from New England and New York, Central Indiana by migrants fro ...
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Kentland Structure - Laney - Schmus Fig 2b (large)
Kentland may refer to a location in the United States: *Kentland, Indiana, in Newton County **Kentland crater ** Kentland Municipal Airport *Kentland, Maryland, in Prince George's County * Kentland Farm Historic and Archeological District near Blacksburg, Virginia ;See also * Kent Land District, Tasmania * Kent Land District, Western Australia *Kentlands, a neighborhood of Gaithersburg, Maryland Gaithersburg ( ), officially the City of Gaithersburg, is a city in Montgomery County, Maryland, United States. At the time of the 2020 U.S. Census, Gaithersburg had a population of 69,657, making it the ninth-largest location in the state. Gai ...