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Wills Creek Formation
Wills Creek Formation is a mapped Silurian bedrock unit in Pennsylvania, Maryland, Virginia, and West Virginia. Description The Wills Creek is defined as a moderately well bedded greenish-gray shale containing local limestone and sandstone zones, or more specifically as an olive to yellowish-gray, thin-bedded sandstone, calcareous shale, dolomite, argillaceous limestone, and sandstone. Red shale and siltstone occur in the lower part of the formation. The formation has a thickness between 450 feet and 600 feet in Maryland and 445 to 620 feet in Pennsylvania. The Wills Creek forms the bedrock of the valley around and to the east of Lewistown, Pennsylvania. Fossils The Wills Creek Limestone contain fossils from the Pridoli to the Ludlow epoch, or 422.9 to 418.1 Ma. Dean et al. (1985) describe the Wills Creek as sparsely fossiliferous. Conodonts have been identified in the Wills Creek in Virginia ('' Ozarkodina snajdri crispa'' Zone).Harris, A.G., Stamm, N.R., Weary, D.J., R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anticline
In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the location where the curvature is greatest, and the limbs are the sides of the fold that dip away from the hinge. Anticlines can be recognized and differentiated from antiforms by a sequence of rock layers that become progressively older toward the center of the fold. Therefore, if age relationships between various rock strata are unknown, the term antiform should be used. The progressing age of the rock strata towards the core and uplifted center, are the trademark indications for evidence of anticlines on a geologic map. These formations occur because anticlinal ridges typically develop above thrust faults during crustal deformations. The uplifted core of the fold causes compression of strata that preferentially erodes to a deeper st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virginia
Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth are shaped by the Blue Ridge Mountains and the Chesapeake Bay, which provide habitat for much of its flora and fauna. The capital of the Commonwealth is Richmond; Virginia Beach is the most-populous city, and Fairfax County is the most-populous political subdivision. The Commonwealth's population was over 8.65million, with 36% of them living in the Baltimore–Washington metropolitan area. The area's history begins with several indigenous groups, including the Powhatan. In 1607, the London Company established the Colony of Virginia as the first permanent English colony in the New World. Virginia's state nickname, the Old Dominion, is a reference to this status. Slave labor and land acquired from displaced native tribes fueled the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of Pennsylvania
The Geology of Pennsylvania consists of six distinct physiographic provinces, three of which are subdivided into different sections. Each province has its own economic advantages and geologic hazards and plays an important role in shaping everyday life in the state. They are: (listed from the southeast corner to the northwest corner) the Atlantic Coastal Plain Province, the Piedmont Province, the New England Province, the Ridge and Valley Province, the Appalachian Plateau Province, and the Central Lowlands Province. A majority of the rocks in Pennsylvania exposed at the surface are sedimentary and were deposited during the Paleozoic Era. Almost all of the metamorphic and igneous rocks are confined to the southeast portion of the state. A total of four orogenies have affected the rocks of the Commonwealth including the Grenville orogeny, the Taconic orogeny, the Acadian orogeny, and the Appalachian orogeny. The Appalachian event has left the most evidence and has continued to sh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unconformity
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger layer, but the term is used to describe any break in the sedimentary geologic record. The significance of angular unconformity (see below) was shown by James Hutton, who found examples of Hutton's Unconformity at Jedburgh in 1787 and at Siccar Point in 1788. The rocks above an unconformity are younger than the rocks beneath (unless the sequence has been overturned). An unconformity represents time during which no sediments were preserved in a region or were subsequently eroded before the next deposition. The local record for that time interval is missing and geologists must use other clues to discover that part of the geologic history of that area. The interval of geologic time not represented is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roundtop Hill (Maryland)
Roundtop Hill is a mountain in Washington County, Maryland, southwest of the town of Hancock. The elevation at the summit is . Geography Unlike surrounding mountains, Roundtop Hill is not part of an extended ridge system, and is only about in length. It is located just under from the crest of Tonoloway Ridge, about southwest of Hancock. Its presence causes a large bend in the Potomac River, which curves around its eastern slope. Much of the eastern face is part of the Chesapeake and Ohio Canal National Historical Park and the canal bed and tow path pass along the narrow bank at its base. Geology Outstanding outcrops of the Silurian Wills Creek Formation and underlying Bloomsburg Formation are exposed along the old railroad grade at Roundtop Hill. Examples of folding, formation of cleavage, thrust faulting In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass move ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ozarkodina Snajdri Crispa
''Ozarkodina'' is an extinct genus of conodonts in the family Spathognathodontidae. Use in stratigraphy ''Ozarkodina snajdri'' forms a subdivision of the '' Pseudomonoclimacis'' latilobus graptolite zone in the Burgsvik beds Silurian formation in Sweden. An ''Ozarkodina snajdri crispa'' zone has also been identified in the Wills Creek in Virginia. ''Ozarkodina derenjalensis'' is found in the Silurian of the Niur Formation in Iran.A new early Silurian prioniodontid conodont with three P elements from Iran and associated species. Peep Männik, C. Giles Miller and Vachik Hairapetian, Acta Palaeontologica Polonica, 2015, volume 60, issue 3, pages 733–746, The Kellwasser event in the Devonian which saw the extinction of all ''Ozarkodina'' species is reported in the list of Global Boundary Stratotype Sections and Points. References External links ''Ozarkodina''at fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megaannum
A year or annus is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the planet, four seasons are generally recognized: spring, summer, autumn and winter. In tropical and subtropical regions, several geographical sectors do not present defined seasons; but in the seasonal tropics, the annual wet and dry seasons are recognized and tracked. A calendar year is an approximation of the number of days of the Earth's orbital period, as counted in a given calendar. The Gregorian calendar, or modern calendar, presents its calendar year to be either a common year of 365 days or a leap year of 366 days, as do the Julian calendars. For the Gregorian calendar, the average length of the calendar year (the mean yea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ludlow Epoch
In the geological timescale, the Ludlow Epoch (from 427.4 ± 0.5 million years ago to 423.0 ± 2.3 million years ago) occurred during the Silurian Period, after the end of the Homerian Age. It is named for the town of Ludlow in Shropshire, England. The Ludlow Epoch is subdivided into two stages: Gorstian and Ludfordian. Paleontology Arthropods See also *Ludlow Group References Ludlow epoch, Silurian geochronology, *03 Geological epochs Ludlow first appearances, {{geochronology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lewistown, Pennsylvania
Lewistown is a borough in and the county seat of Mifflin County, Pennsylvania, United States. It is the principal city of the '' Lewistown, PA Micropolitan Statistical Area'', which encompasses all of Mifflin County. It lies along the Juniata River, northwest of Harrisburg. The number of people living in the borough in 1900 was 4,451; in 1910, 8,166; in 1940, 13,017; and in 2000, 8,998. The population was 8,561 at the 2020 census. Of the four communities in the United States named "Lewistown", this borough is the largest. History Early history The borough was incorporated in 1795 and was named for William "Bill" Lewis, a Quaker and a member of the legislature, who was responsible for the designation of the borough, which was then known as the Village of Ohesson, as the county seat of Mifflin County. During the late 19th century Mifflin County became the crossroads of the Commonwealth. Located near the geographic center of the state, the area became a hub for traffic m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pennsylvania State University
The Pennsylvania State University (Penn State or PSU) is a Public university, public Commonwealth System of Higher Education, state-related Land-grant university, land-grant research university with campuses and facilities throughout Pennsylvania. Founded in 1855 as the Farmers' High School of Pennsylvania, Penn State became the state's only Land-grant university, land-grant university in 1863. Today, Penn State is a major research university which conducts teaching, research, and public service. Its instructional mission includes undergraduate, graduate, professional and continuing education offered through resident instruction and online delivery. The University Park campus has been labeled one of the "Public Ivy, Public Ivies", a publicly funded university considered as providing a quality of education comparable to those of the Ivy League. In addition to its land-grant designation, it also participates in the sea-grant, space-grant, and sun-grant research consortia; it is on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argillaceous
Clay minerals are hydrous aluminium phyllosilicates (e.g. kaolin, Al2 Si2 O5( OH)4), sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces. Clay minerals form in the presence of water and have been important to life, and many theories of abiogenesis involve them. They are important constituents of soils, and have been useful to humans since ancient times in agriculture and manufacturing. Properties Clay is a very fine-grained geologic material that develops plasticity when wet, but becomes hard, brittle and non–plastic upon drying or firing. It is a very common material, and is the oldest known ceramic. Prehistoric humans discovered the useful properties of clay and used it for making pottery. The chemistry of clay, including its capacity to retain nutrient cations such as potassium and ammonium, is important to soil fertility. Because the individual particles in clay are less than ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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