Newark Supergroup
The Newark Supergroup, also known as the Newark Group, is an assemblage of Upper Triassic and Lower Jurassic sedimentary rocks which outcrop intermittently along the United States East Coast. They were deposited in a series of Triassic basins app ...
's
Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
rift basins
In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics.
Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-grabe ...
. It lies east of the
Appalachian Mountains
The Appalachian Mountains, often called the Appalachians, (french: Appalaches), are a system of mountains in eastern to northeastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. They ...
Orange County
Orange County most commonly refers to:
*Orange County, California, part of the Los Angeles metropolitan area
Orange County may also refer to:
U.S. counties
*Orange County, Florida, containing Orlando
*Orange County, Indiana
*Orange County, New ...
line in
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 ar ...
to
Frederick Frederick may refer to:
People
* Frederick (given name), the name
Nobility
Anhalt-Harzgerode
*Frederick, Prince of Anhalt-Harzgerode (1613–1670)
Austria
* Frederick I, Duke of Austria (Babenberg), Duke of Austria from 1195 to 1198
* Frederick ...
,
Maryland
Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to ...
siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...
,
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates) ...
, and congolmerate within the basin were intruded by igneous rocks (primarily
diabase
Diabase (), also called dolerite () or microgabbro,
is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-graine ...
), which caused thermal
metamorphism
Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chem ...
at the contact with sedimentary rock.''Geologic history and stratigraphy of the Triassic-Jurassic Culpeper Basin, Virginia'', R. C. Lindholm. GSA Bulletin (1979) 90 (11_Part_II): 1702–1736. https://doi.org/10.1130/GSAB-P2-90-1702
The Culpeper Basin is nearly continuous with the
Gettysburg Basin Gettysburg may refer to:
Events
* Gettysburg Campaign, a series of American Civil War military engagements in the Main Eastern Theater.
** Battle of Gettysburg, July 1–3 military engagements during the 1863 Gettysburg Campaign
** Retreat from G ...
to the north and with the
Barboursville Basin Barboursville is the name of several places in the United States of America:
* Barboursville, Virginia
* Barboursville, West Virginia
* Barboursville (James Barbour) the Virginia home of James Barbour
* Barboursville Vineyards
Barboursville Vine ...
to the south.
The
Groveton Member Groveton may refer to a community in the United States:
* Groveton, New Hampshire
* Groveton, Texas
* Groveton, Virginia
Groveton is a census-designated place (CDP) in Fairfax County, Virginia, United States. The population was 14,598 at the 2010 ...
of the
Bull Run Formation
The Bull Run Formation is a Late Triassic ( Norian) stratigraphic unit in the eastern United States. The formation has produced disarticulated fish remains including isolated bones and scales.
The large body of diabase in central Montgomery County, Maryland, is known as the Boyds Sill,Fisher, G. W., 1964, The Triassic rocks of Montgomery County. ''In'' Geology of Howard and Montgomery Counties, Maryland Geological Survey, Baltimore, Maryland, 1964.) named after the town of Boyds.
File:Diabase boulders 20210302.jpg, Jurassic
diabase
Diabase (), also called dolerite () or microgabbro,
is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-graine ...
boulders in the Culpeper Basin northeast of
Dulles Airport
Washington Dulles International Airport , typically referred to as Dulles International Airport, Dulles Airport, Washington Dulles, or simply Dulles ( ), is an international airport in the Eastern United States, located in Loudoun County and Fai ...
File:Balls Bluff Siltstone with Diabase Intrusion (4802113326).jpg, Balls Bluff Siltstone with diabase intrusion, northern face of Luck Stone Quarry, Manassas
File:Leesburg Member, Balls Bluff Siltstone (4802116200).jpg, Limestone conglomerate of Leesburg Member
File:Limestone conglomerate Leesburg VA Lb1.jpg, Another sample of limestone conglomerate
File:Sandstone Culpepper Basin Maryland.jpg, Sandstone from southwest the Boyds Sill in Montgomery County, Maryland
File:Diabase of Boyds Sill Hoyles Mill Trail 2021.jpg, Unnamed stream exposing diabase of Boyds Sill, Hoyles Mill Trail, Montgomery County, Maryland
Footnotes
References
* Hunt, ReBecca K., Vincent L. Santucci and Jason Kenworthy. 2006. "A preliminary inventory of fossil fish from National Park Service units." in S.G. Lucas, J.A. Spielmann, P.M. Hester, J.P. Kenworthy, and V.L. Santucci (ed.s), Fossils from Federal Lands. New Mexico Museum of Natural History and Science Bulletin 34, pp. 63–69.
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Geology of Maryland