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List Of Mapped Rock Formations In Pennsylvania
The following is a list of the mapped bedrock units in Pennsylvania. The rocks are listed in stratigraphic order.Berg, T.M., et al., (1983). Stratigraphic Correlation Chart of Pennsylvania: G75, Pennsylvania Geologic Survey, Harrisburg, Pennsylvania. Note: Some of the Formations are laterally equivalent in age. They are listed in order from West to East in this case. References {{reflist See also * Geology of Pennsylvania * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pennsylvania
Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, Maryland to its south, West Virginia to its southwest, Ohio to its west, Lake Erie and the Canadian province of Ontario to its northwest, New York to its north, and the Delaware River and New Jersey to its east. Pennsylvania is the fifth-most populous state in the nation with over 13 million residents as of 2020. It is the 33rd-largest state by area and ranks ninth among all states in population density. The southeastern Delaware Valley metropolitan area comprises and surrounds Philadelphia, the state's largest and nation's sixth most populous city. Another 2.37 million reside in Greater Pittsburgh in the southwest, centered around Pittsburgh, the state's second-largest and Western Pennsylvania's largest city. The state's su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Onondaga Formation
The Onondaga Limestone is a group of hard limestones and dolomites of Devonian age that form an important geographic feature in some areas in which it outcrops; in others, especially its Southern Ontario portion, the formation can be less prominent as a local surface feature. In upstate New York and southern Ontario the sedimentary rocks tend to slope slightly southward, and the Onondaga outcrops in a line that usually forms an escarpment (the steep face of a cuesta), because of its resistance to erosion. The outcrop can be traced from the Hudson River valley westward along the southern rim of the Mohawk River valley, passing just south of Syracuse, and along the northern heads of the major Finger Lakes to Buffalo, New York. From Fort Erie, Ontario it runs to Windsor just north of the Lake Erie shoreline, becoming less prominent as one travels westward. It is not distinct west of Windsor, but begins to become noticeable as a steep hill just northwest of Leamington, as it forms a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marcellus Formation
The Marcellus Formation or the Marcellus Shale is a Middle Devonian age unit of sedimentary rock found in eastern North America. Named for a distinctive outcrop near the village of Marcellus, New York, in the United States, it extends throughout much of the Appalachian Basin. The unit name usage by the U.S. Geological Survey (USGS) includes ''Marcellus Shale'' and ''Marcellus Formation''.See unit names marked by an asterisk aGeolex/ref> The term "Marcellus Shale" is the preferred name throughout most of the Appalachian region, although the term "Marcellus Formation" is also acceptable within the State of Pennsylvania. The unit was first described and named as the "Marcellus shales" by J. Hall in 1839. Description The Marcellus consists predominantly of black shale and a few limestone beds and concentrations of iron pyrite ( Fe S2) and siderite (Fe CO3). Like most shales, it tends to split easily along the bedding plane, a property known as fissility. Lighter colored ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mahantango Formation
The Devonian Mahantango Formation is a mapped bedrock unit in Pennsylvania, West Virginia, and Maryland. It is named for the North branch of the Mahantango Creek in Perry and Juniata counties in Pennsylvania. It is a member of the Hamilton Group, along with the underlying the Marcellus Formation Shale. South of Tuscarora Mountain in south central Pennsylvania, the lower members of this unit were also mapped as the Montebello Formation. Details of the type section and of stratigraphic nomenclature for this unit as used by the U.S. Geological Survey are available on-line at the National Geologic Map Database. Description The Mahantango Formation is a gray, brown, and olive siltstone and shale, characterized by coarsening-upward cycles. Stratigraphic Setting The Mahantango Formation is typically found conformally overlying the Marcellus Formation, and underlying the Tully Limestone (where present). The Mahantango has been divided into four members: *Tully Limestone: a fossili ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hamilton Group
The Hamilton Group is a Devonian-age geological group in the Appalachian region of the United States. It is present in New York, Pennsylvania, Maryland, Ohio, West Virginia, northwestern Virginia and Ontario, Canada. It is mainly composed of marine shale with some sandstone. There are two main formations encompassed by the group: the Mahantango Formation and the Marcellus Shale. In southwestern Virginia, where the two sub-units are not easily distinguishable, the Hamilton Group is broadly equivalent to the Millboro Shale or Millboro Formation. The group is named for the village of Hamilton, New York. These rocks are the oldest strata of the Devonian gas shale sequence. Stratigraphic Setting The Hamilton Group consists of the Mahantango Formation, a gray, dark gray, brown, and olive laminated shale; siltstone; and very fine-grained sandstone or claystone containing marine fossils. The uppermost clay layers of the Mahantango Formation are particularly rich in fossils. It overlies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harrell Formation
The Devonian Harrell Formation is a mapped bedrock unit in Pennsylvania, Maryland, West Virginia, and Virginia. Description The Harrell Formation was first described by Charles Butts in 1918. Hasson and Dennison (1978) state "The Harrell Shale consists of very dark gray, thinly laminated, platy- to sheety-weathering shale underlain in certain areas by the grayish black shale of the Burket Member." Fossils Hasson and Dennison reported the following fossils from several outcrops of the Harrell:Hasson, Kenneth O., and Dennison, John M., 1978, STRATIGRAPHY OF THE DEVONIAN HARRELL AND MILLBORO SHALES IN PARTS OF PENNSYLVANIA, MARYLAND, WEST VIRGINIA, AND VIRGINIA, Project Final Report for Energy Research and Development Administration Contract #EY-77-C-21-8153, May 197/ref> *Bivalvia: ''Buchiola livonae'' (?), ''B. retrostriata'', ''Paracardium doris'', ''Pterochaenia fragilis'', ''Lunlulicardium'' (?) *Cephalopoda: ''Bactrites aciculum'', ''Probeloceras lutheri'' *Cricoconarida (cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brallier Formation
The Devonian Brallier Formation is a mapped bedrock unit in Pennsylvania, Maryland, West Virginia, and Virginia. Description The Brallier Formation was described by Charles Butts in 1918 as a fine-grained, siliceous shale with few fine-grained sandstone layers, from outcrops in central Pennsylvania. Others expanded usage of the term to rocks in other states. Stratigraphy The Brallier is roughly equivalent to the Scherr Formation. The contact with the underlying Harrell Formation is generally gradational. Fossils Hasson and Dennison reported the following fossils from outcrops of the lower Brallier at Keyser, West Virginia, Ridgeville, West Virginia, and McCoole, Maryland:Hasson, Kenneth O., and Dennison, John M., 1978, STRATIGRAPHY OF THE DEVONIAN HARRELL AND MILLBORO SHALES IN PARTS OF PENNSYLVANIA, MARYLAND, WEST VIRGINIA, AND VIRGINIA, Project Final Report for Energy Research and Development Administration Contract #EY-77-C-21-8153, May 197/ref> *Bivalvia: ''Buchiola retro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catskill Formation
The Devonian Catskill Formation or the Catskill Clastic wedge is a unit of mostly terrestrial sedimentary rock found in Pennsylvania and New York. Minor marine layers exist in this thick rock unit (up to ). It is equivalent to the Hampshire Formation of Maryland, West Virginia, and Virginia. The Catskill is the largest bedrock unit of the Upper Devonian in northeast Pennsylvania and the Catskill region of New York, from which its name is derived. The Pocono Mountains of Pennsylvania are largely underlain by this unit as well. The rocks of the Catskill are predominantly red sandstone indicating a large scale terrestrial deposition during the Acadian orogeny. Many beds are cyclical in nature, preserving the record of a dynamic environment during its approximately 20 million years of deposition. Depositional environment During the Devonian period, the Catskill Delta was formed by a series of river deltas and otherwise marshy terrain. This terrain was sandwiched between the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Huntley Mountain Formation
The Huntley Mountain Formation is a late Devonian and early Mississippian mapped bedrock unit in Pennsylvania, in the United States. Description The formation is composed of relatively soft grayish-red 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, especial ... and olive-gray sandstone. It is located in north central Pennsylvania. Haystacks The Haystacks are enigmatic mounds of sandstone that outcrop in Loyalsock Creek south of Dushore in Sullivan County. They are a single bed of quartz sandstone with an undulating upper surface with up to one meter relief. The origin of the mounds is debatable. Notable Exposures * The type section of the formation is at Huntley Mountain in Lycoming County, Pennsylvania, on the mountainside just north of the village of Waterville. * Base ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rockwell Formation
The Rockwell Formation is a late Devonian and early Mississippian mapped bedrock unit in West Virginia, Maryland, and Pennsylvania, in the United States. Description The Rockwell Formation was described at its type section at Rockwell Run in West Virginia as soft arkosic sandstone, fine hard conglomerate, and buff hackly shale. The formation was originally described in West Virginia by Stose and Swartz (1912). It was first described in Maryland by H. E. Vokes (1957),Vokes, H.E., 1957, Geography and geology of Maryland: Maryland Geological Survey Bulletin, no. 19, p. 243. and later described in central Pennsylvania by C. R. Wood (1980).Wood, C.R., 1980, Summary groundwater resources of Centre County, Pennsylvania: Pennsylvania Geological Survey Water Resource Report, 4th series, no. 48, p. 60. Stratigraphy The Rockwell is generally considered a Formation. At Formation rank, it has several members, including the Patton and Riddlesburg Shale Members,Kammer, T.W., and Bjerstedt, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
