The Triassic

Triassic

The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

 Stockton Formation is a mapped bedrock unit in Pennsylvania

Pennsylvania

The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...

, New Jersey

New Jersey

New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...

, and New York

New York

New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

. It is named after Stockton, New Jersey

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...

, where it was first described. It is laterally equivalent to the New Oxford Formation

New Oxford Formation

-Vertebrate fauna:...

 in the Gettysburg Basin of Pennsylvania and Maryland

Maryland

Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...

.

Description

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

Sandstone

Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...

 and reddish to purplish-brown siltstone

Siltstone

Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystones.- Description :As its name implies, it is primarily composed of silt sized particles, defined as grains 1/16 - 1/256 mm or 4 to 8 on the Krumbein phi scale...

 and mudstone

Mudstone

Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...

 with shale interbeds; and interbedded argillite. In New Jersey, feldspar pebbly sandstone and conglomerate

Conglomerate (geology)

A conglomerate is a rock consisting of individual clasts within a finer-grained matrix that have become cemented together. Conglomerates are sedimentary rocks consisting of rounded fragments and are thus differentiated from breccias, which consist of angular clasts...

, and quartz

Quartz

Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...

-pebble

Pebble

A pebble is a clast of rock with a particle size of 4 to 64 millimetres based on the Krumbein phi scale of sedimentology. Pebbles are generally considered to be larger than granules and smaller than cobbles . A rock made predominantly of pebbles is termed a conglomerate...

 conglomerate are also mapped.

Depositional Environment

The Stockton is described as a bajada

Bajada

Bajada may refer to:*Bajada a festival common to the Canary islands* Bajada, a compound Alluvial fan* La Bajada, an escarpment of the Caja del Rio, New Mexico, USA* Clint Bajada , Maltese TV and radio personality...

. The sediments were a result of the rifting of Pangea. The sediments came from the southeast from a largely granitic

Granite

Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...

 terrane and spread across an even plain. Interfingered with the Stockton, the Lockatong Formation

Lockatong Formation

The Triassic Lockatong Formation is a mapped bedrock unit in Pennsylvania, New Jersey, and New York. It is named after the Lockatong Creek in Hunterdon County, New Jersey.-Description:...

 are lake sediments, which grew during wetter climatic cycles during the late Triassic.

Age

Relative age dating of the Stockton places it in the Upper Triassic

Triassic

The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

 period, being deposited between 237 to 207 (±5) million years ago. It rests unconformably

Unconformity

An unconformity is a buried erosion 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, but the term is used to describe...

 a top many different formations of the Appalachian Piedmont

Piedmont (United States)

The Piedmont is a plateau region located in the eastern United States between the Atlantic Coastal Plain and the main Appalachian Mountains, stretching from New Jersey in the north to central Alabama in the south. The Piedmont province is a physiographic province of the larger Appalachian division...

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

Passaic Formation

The Passaic Formation is a mapped bedrock unit in Pennsylvania, New Jersey, and New York. It was previously known as the Brunswick Formation since it was first described in the vicinity of New Brunswick, New Jersey. It is now named for the city of Passaic, New Jersey, which is near where its type...

. There are numerous diabase

Diabase

Diabase or dolerite is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. In North American usage, the term diabase refers to the fresh rock, whilst elsewhere the term dolerite is used for the fresh rock and diabase refers to altered material...

 intrusions into the Stockton with local contact metamorphic

Metamorphic rock

Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...

 rocks.

See also

• Geology of Pennsylvania
  Geology of Pennsylvania
  The Geology of Pennsylvania consists of six distinct physiographic provinces, three of which are subdivided into different sections. Each province has its own economic advantages and geologic hazards and play an important role in shaping everyday life in the state...
  
  
• Geology of New Jersey
  Geology of New Jersey
  The Geology of New Jersey consists of four distinct physiographic provinces. They are: the Atlantic Coastal Plain Province, the Piedmont Province, the Highlands Province, and the Ridge and Valley Province.-Coastal Plain:...