The New Oxford Formation is a mapped bedrock unit consisting primarily of sandstones, conglomerates, and shales. The New Oxford Formation was first described in

Adams County, Pennsylvania Adams County is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population was 103,852. Its county seat is Gettysburg. The county was created on January 22, 1800, from part of York County, and was named for the second ...

in 1929, and over the following decade was mapped in adjacent

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 C ...

Stose, 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 Frederick County is located in the northern part of the U.S. state of Maryland. At the 2020 U.S. Census, the population was 271,717. The county seat is Frederick. Frederick County is included in the Washington-Arlington-Alexandria, DC-VA-MD ...

.Jonas, A.I., and Stose, G.W., 1938, Geologic map of Frederick County and adjacent parts of Washington and Carroll Counties (Maryland): Maryland Geological Survey County Geologic Map, 1 sheet, scale 1:62,500 It was described as "red shale and sandstone with beds of micaceous sandstone, arkose, and conglomerate." The majority of this early mapping was done by George Willis Stose, Anna Isabel Jonas, and Florence Bascom.

Depositional Environment

The New Oxford Formation and other formations of the

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 ...

were deposited in the Gettysburg Basin, just one of many Triassic rift basins existing on the east coast of North and South America, which formed as

plate tectonics Plate tectonics (from the la, label= Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large t ...

pulled apart

Pangaea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 millio ...

into the

continent A continent is any of several large landmasses. Generally identified by convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continents. Ordered from largest in area to smallest, these seven ...

s we see today.

Stratigraphy

The New Oxford Formation is overlain by the

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 dec ...

and in

Adams Adams may refer to: * For persons, see Adams (surname) Places United States *Adams, California *Adams, California, former name of Corte Madera, California *Adams, Decatur County, Indiana *Adams, Kentucky *Adams, Massachusetts, a New England town ...

, Cumberland,

Lancaster Lancaster may refer to: Lands and titles *The County Palatine of Lancaster, a synonym for Lancashire *Duchy of Lancaster, one of only two British royal duchies *Duke of Lancaster *Earl of Lancaster *House of Lancaster, a British royal dynasty ...

, and

York York is a cathedral city with Roman Britain, Roman origins, sited at the confluence of the rivers River Ouse, Yorkshire, Ouse and River Foss, Foss in North Yorkshire, England. It is the historic county town of Yorkshire. The city has many hist ...

Counties in Pennsylvania. In all other areas to the northeast in Pennsylvania the New Oxford Formation is overlain by the

Hammer Creek Formation The Hammer Creek Formation is a mapped bedrock unit consisting primarily of conglomerate, coarse sandstone, and shale. The Hammer Creek Formation was originally mapped as part of the Gettysburg Formation in Adams County, Pennsylvania in 1929. ...

.Wood, C. R., 1980, Groundwater resources of the Gettysburg and Hammer Creek Formations, southeastern Pennsylvania: Pennsylvania Geological Survey, 4th ser., Water Resource Report 49, 87 p. (se
W 49
. The New Oxford Formation overlies

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 th ...

and

paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

rocks at the bottom of the Gettysburg Basin. The New Oxford Formation is not divided into members.

Paleofauna

Vertebrate paleofauna

The New Oxford Formation contains mainly

tetrapod Tetrapods (; ) are four-limb (anatomy), limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant taxon, extant and extinct amphibians, sauropsids (reptiles, including dinosaurs and therefore birds) and synapsids (p ...

fossils, including

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

remains.Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Triassic, North America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 518–521. .

Paleoflora

* '' Acrostichites linnaeaefolius'' * '' Acrostichites microphyllus'' * '' Anomozamites princeps'' * '' Araucarites? pennsylvaninicus'' * '' Araucarites yorkensis'' * '' Asterocarpus falcatus'' * '' Baiera muensteriana'' * '' Brachyphyllum yorkense'' *

cf. The abbreviation ''cf.'' (short for the la, confer/conferatur, both meaning "compare") is used in writing to refer the reader to other material to make a comparison with the topic being discussed. Style guides recommend that ''cf.'' be used onl ...

Brachyphyllum ''Brachyphyllum'' (meaning "short leaf") is a form genus of fossil coniferous plant foliage. Plants of the genus have been variously assigned to several different conifer groups including Araucariaceae and Cheirolepidiaceae. They are known from ...

'' cf. ''yorkense'' * '' Cheirolepis muensteri'' * '' Cladophlebis reticulata'' * '' Conewagia longiloba'' * '' Ctenophyllum grandifolium'' * '' Ctenophyllum wannerianum'' * '' Cycademyelon yorkense'' * '' Cycadeospermum wanneri'' * '' Dioonites carnallianus'' * '' Equisetum rogersii'' * '' Lonchopteris oblonga'' * '' Macrotaeniopteris magnifolia'' * '' Palissya diffusa'' * '' Palissya sphenolepis'' * '' Podozamites distans'' * '' Pseudoddanaeopis plana'' * '' Pterophyllum inaequale'' * ''

Sagenopteris ''Sagenopteris'' is a genus of extinct seed ferns from the Triassic to late Early Cretaceous.

'' sp. * '' Schizolepis liaso-kueperinus'' * '' Sphenozamites rogersianus'' * '' Taeniopteris? yorkensis'' * '' Thinnfeldia? reticulata'' * '' Yorkia gramineoides'' * '' Zamites pennsylvanicus'' * '' Zamites yorkensis''

Age

Relative age dating of the New Oxford Formation places it in the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ...

period, around ~221.5–205.6 Ma (

Norian The Norian is a division of the Triassic Period. It has the rank of an age ( geochronology) or stage (chronostratigraphy). It lasted from ~227 to million years ago. It was preceded by the Carnian and succeeded by the Rhaetian. Stratigraphic ...

Rhaetian The Rhaetian is the latest age of the Triassic Period (in geochronology) or the uppermost stage of the Triassic System (in chronostratigraphy). It was preceded by the Norian and succeeded by the Hettangian (the lowermost stage or earliest ...

), possibly reaching as old as 230 Ma (

Carnian The Carnian (less commonly, Karnian) is the lowermost stage of the Upper Triassic Series (or earliest age of the Late Triassic Epoch). It lasted from 237 to 227 million years ago (Ma). The Carnian is preceded by the Ladinian and is followe ...

) in some places.

References

Triassic geology of Pennsylvania Carnian Stage {{Pennsylvania-geologic-formation-stub