The

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 ...

Stockton Formation is a mapped bedrock unit in

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, Ma ...

New Jersey New Jersey is a U.S. state, state in the Mid-Atlantic States, Mid-Atlantic and Northeastern United States, Northeastern regions of the United States. It is bordered on the north and east by the state of New York (state), New York; on the ea ...

, and

New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...

. It is named after

Stockton, New Jersey Stockton is a borough in Hunterdon County, New Jersey, United States. The borough sits on the Delaware River at the western end of Amwell Valley. As of the 2010 United States Census, the borough's population was 538,< ...

, where it was first described. It is laterally equivalent to the New Oxford Formation in the Gettysburg Basin of Pennsylvania and

Maryland Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), 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; ...

.Faill, R.T., (2004). The Birdsboro Basin. ''Pennsylvania Geology'' V. 34 n. 4.

Description

The Stockton is defined as a light-gray to light brown and yellowish medium to coarse grained

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 reddish to purplish-brown

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, ...

and mudstone with shale interbeds; and interbedded

argillite :''"Argillite" may also refer to Argillite, Kentucky.'' Argillite () is a fine-grained sedimentary rock composed predominantly of indurated clay particles. Argillaceous rocks are basically lithified muds and oozes. They contain variable amo ...

. In New Jersey,

feldspar Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feld ...

pebbly sandstone and conglomerate, and

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

pebble A pebble is a clast of rock with a particle size of based on the Udden-Wentworth scale of sedimentology. Pebbles are generally considered larger than granules ( in diameter) and smaller than cobbles ( in diameter). A rock made predomina ...

conglomerate are also mapped.

Depositional environment

The Stockton is described as a bajada. The sediments were a result of the rifting of

Pangea 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 million ...

. The sediments came from the southeast from a largely

granitic A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quart ...

terrane and spread across an even plain. Interfingered with the Stockton, the Lockatong Formation are lake sediments, which grew during wetter climatic cycles during 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 ...

Fossils

Some fossils found within the Stockton Formation are fossil ferns including '' Sphenopteris sitholeyi''. (''Virginia Museum of Natural History Guidebook, no 1, p83.'')

Age

Relative age dating of the Stockton places it in the Upper

System, i.e., deposition between 237 and 207 (±5) million years ago. It rests unconformably a top many different formations of the Appalachian

Piedmont it, Piemontese , population_note = , population_blank1_title = , population_blank1 = , demographics_type1 = , demographics1_footnotes = , demographics1_title1 = , demographics1_info1 = , demographics1_title2 ...

. It interfingers with the Lockatong Formation and also rests conformably below the Passaic Formation. There are numerous

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-gra ...

intrusions into the Stockton with local contact metamorphic rocks.Berg, T.M., et al., (1983). Stratigraphic Correlation Chart of Pennsylvania: G75, Pennsylvania Geological Survey, Harrisburg, Pennsylvania.

Description

Depositional environment

Fossils

Age

References

See also