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Gettysburg Formation
The Gettysburg Formation is a mapped bedrock unit consisting primarily of sandstones, conglomerates, and shales. The Gettysburg Formation was first described in the Gettysburg area of Adams County, Pennsylvania in 1929, and over the following decade was mapped in adjacent York County, PennsylvaniaStose, G.W., and Jonas, A.I., 1939, Geology and mineral resources of York County, Pennsylvania: Pennsylvania Geological Survey County Report, 4th series, no. 67, 199 p. and Frederick County, Maryland. It was then typically called the "Gettysburg shale," and was described as "thick red shales and soft red sandstones." The majority of this early mapping was done by G. W. Stose, A. I. Jonas, and Florence Bascom. Later workers described it as "Red, medium- to fine-grained sandstone and shale." The rock unit was formalized into a Formation in 1963 by J. D. Glaeser. Glaeser re-mapped some areas previously mapped as the Gettysburg Formation to the Hammer Creek Formation. A major groundwate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
York County, Pennsylvania
York County ( Pennsylvania Dutch: Yarrick Kaundi) is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population was 456,438. Its county seat is York. The county was created on August 19, 1749, from part of Lancaster County and named either after the Duke of York, an early patron of the Penn family, or for the city and county of York in England. York County comprises the York-Hanover, Pennsylvania Metropolitan Statistical Area, which is also included in the Harrisburg-York-Lebanon, Pennsylvania Combined Statistical Area. It is in the Susquehanna Valley, a large fertile agricultural region in South Central Pennsylvania. Based on the Articles of Confederation having been adopted in York by the Second Continental Congress on November 15, 1777, the local government and business community began referring to York in the 1960s as the first capital of the United States of America. The designation has been debated by historians ever since. Congress cons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precambrian
The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic Eon, which is named after Cambria, the Latinised name for Wales, where rocks from this age were first studied. The Precambrian accounts for 88% of the Earth's geologic time. The Precambrian is an informal unit of geologic time, subdivided into three eons ( Hadean, Archean, Proterozoic) of the geologic time scale. It spans from the formation of Earth about 4.6 billion years ago ( Ga) to the beginning of the Cambrian Period, about million years ago ( Ma), when hard-shelled creatures first appeared in abundance. Overview Relatively little is known about the Precambrian, despite it making up roughly seven-eighths of the Earth's history, and what is known has largely been discovered from the 1960s onwards. The Precambrian fossil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theropod
Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally carnivorous, although a number of theropod groups evolved to become herbivores and omnivores. Theropods first appeared during the Carnian age of the late Triassic period 231.4 million years ago ( Ma) and included all the large terrestrial carnivores from the Early Jurassic until at least the close of the Cretaceous, about 66 Ma. In the Jurassic, birds evolved from small specialized coelurosaurian theropods, and are today represented by about 10,500 living species. Biology Diet and teeth Theropods exhibit a wide range of diets, from insectivores to herbivores and carnivores. Strict carnivory has always been considered the ancestral diet for theropods as a group, and a wider variety of diets was historically considered a characteri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palynomorph
Palynology is the "study of dust" (from grc-gre, παλύνω, palynō, "strew, sprinkle" and '' -logy'') or of "particles that are strewn". A classic palynologist analyses particulate samples collected from the air, from water, or from deposits including sediments of any age. The condition and identification of those particles, organic and inorganic, give the palynologist clues to the life, environment, and energetic conditions that produced them. The term is commonly used to refer to a subset of the discipline, which is defined as "the study of microscopic objects of macromolecular organic composition (i.e., compounds of carbon, hydrogen, nitrogen and oxygen), not capable of dissolution in hydrochloric or hydrofluoric acids". It is the science that studies contemporary and fossil palynomorphs (paleopalynology), including pollen, spores, orbicules, dinocysts, acritarchs, chitinozoans and scolecodonts, together with particulate organic matter (POM) and kerogen found in sedime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conewago Mountains
The Conewago Mountains or Conewago Hills are a low range of mountains in northern York County, Pennsylvania. They run northeasterly across the county. They form the backdrop to Gifford Pinchot State Park and parallel Conewago Creek. The Conewago Mountains played a role in the early colonization and settling of the region, with settlers north of the mountains being predominantly Scotch-Irish and those south of the range being mostly Germans from the Palatinate region. The mountains provided a source of timber and firewood, and small iron foundries dotted the valley below to smelt iron ore taken from the Conewagos. During the American Civil War, Confederate cavalry under J.E.B. Stuart crossed over the mountains at the hamlet of Mount Royal in Dover Township en route from the Battle of Hanover to Carlisle. Scores of farms in the region were raided for horses, and many farmers hid their livestock in the Conewago Mountains to secret them from the passing Confederates. Today, the mou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conglomerate (geology)
Conglomerate () is a clastic sedimentary rock that is composed of a substantial fraction of rounded to subangular gravel-size clasts. A conglomerate typically contains a matrix of finer-grained sediments, such as sand, silt, or clay, which fills the interstices between the clasts. The clasts and matrix are typically cemented by calcium carbonate, iron oxide, silica, or hardened clay. Conglomerates form by the consolidation and lithification of gravel. They can be found in sedimentary rock sequences of all ages but probably make up less than 1 percent by weight of all sedimentary rocks. In terms of origin and depositional mechanisms, they are closely related to sandstones and exhibit many of the same types of sedimentary structures, e.g., tabular and trough cross-bedding and graded bedding.Boggs, S. (2006) ''Principles of Sedimentology and Stratigraphy.'', 2nd ed. Prentice Hall, New York. 662 pp. Friedman, G.M. (2003) ''Classification of sediments and sedimentary rocks.'' In G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
York Haven Diabase
The York Haven Diabase is a rock formation in Pennsylvania, United States. It underlies the Rossville Diabase and is Jurassic in age. The formation is volcanic to subvolcanic, with a mafic composition and is categorized as a basalt. The York Haven Diabase is a member of the larger Gettysburg Basin. It plays an important role in United States history as the diabase outcrops were useful barriers in the union's strategy against the confederates at the Battle of Gettysburg. Formation The York Haven Diabase began as one of many trough-like basins, which stretched from what is today northern New Jersey towards the northernmost tip of Virginia. These basins opened during the Mesozoic Era along the eastern continental margin of North America and created areas for sediments and lava flows to settle. These are inundated with intrusions, with all of them being primarily tholeiitic. The York Haven Diabase is considered to have a high titanium oxide (TiO2) content and darker color, which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lebanon County, Pennsylvania
Lebanon County ( Pennsylvania Dutch: Lebanon Kaundi) is a county in the Commonwealth of Pennsylvania. As of the 2010 census, the population was 133,568. Its county seat is the city of Lebanon. The county was formed from portions of Dauphin and Lancaster counties in 1813, with minor boundary revisions in 1814 and 1821. Lebanon County comprises the Lebanon, Pennsylvania, metropolitan statistical, which is part of the Harrisburg–York–Lebanon combined statistical area. Lebanon is 72 miles northwest of Philadelphia, which is the nearest major city. Geography According to the U.S. Census Bureau, the county has a total area of , of which is land and (0.2%) is water. Most of it is drained by the Swatara Creek into the Susquehanna River while some eastern portions are drained by the Tulpehocken Creek (which originates in the county near Myerstown) eastward into the Schuylkill River. It consists in large part of a valley. Climate The county has a hot-summer humid contine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dauphin County, Pennsylvania
Dauphin County (; Pennsylvania Dutch: Daffin Kaundi) is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population was 286,401. The county seat and the largest city is Harrisburg, Pennsylvania's state capital and ninth largest city. The county was created ("erected") on March 4, 1785, from part of Lancaster County and was named after Louis Joseph, Dauphin of France, the first son of King Louis XVI. Dauphin County is included in the Harrisburg–Carlisle Metropolitan Statistical Area. Located within the county is Three Mile Island Nuclear Generating Station, site of the 1979 nuclear core meltdown. The nuclear power plant closed in 2019. Geography According to the U.S. Census Bureau, the county has a total area of , of which is land and (5.9%) is water. The county is bound to its western border by the Susquehanna River (with the exception of a small peninsula next to Duncannon). The area code is 717 with an overlay of 223. Adjacent counties * N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lancaster County, Pennsylvania
Lancaster County (; Pennsylvania Dutch: Lengeschder Kaundi), sometimes nicknamed the Garden Spot of America or Pennsylvania Dutch Country, is a county in the Commonwealth of Pennsylvania. It is located in the south central part of Pennsylvania. As of the 2020 census, the population was 552,984. Its county seat is Lancaster. Lancaster County comprises the Lancaster, Pennsylvania metropolitan statistical area. Lancaster County is a tourist destination with its Amish community a major attraction. Contrary to popular belief, the word "Dutch" in "Pennsylvania Dutch" is not a mistranslation, but rather a corruption of the Pennsylvania German endonym ''Deitsch'', which means "Pennsylvania Dutch / German" or "German". Ultimately, the terms Deitsch, Dutch, Diets, and Deutsch are all cognates of the Proto-Germanic word meaning "popular" or "of the people". The continued use of "Dutch" instead of "German" was strengthened by the Pennsylvania Dutch in the 19th century as a way of distin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cumberland County, Pennsylvania
Cumberland County is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population was 259,469. Its county seat is Carlisle. Cumberland County is included in the Harrisburg–Carlisle metropolitan statistical area. History Cumberland County was first settled by a majority of Scots-Irish immigrants who arrived in this area about 1730. English and German settlers constituted about ten percent of the early population. The settlers originally mostly devoted the area to farming and later developed other trades. These settlers built the Middle Spring Presbyterian Church, among the oldest houses of worship in central Pennsylvania, in 1738 near present-day Shippensburg, Pennsylvania. The General Assembly (legislature) of the Pennsylvania colony on January 27, 1750, created Cumberland County from Lancaster County, Pennsylvania, naming it for Cumberland, England. Its county seat is Carlisle. The county also lies within the Cumberland Valley adjoining the Susq ... [...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] |
