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New Scotland Formation

New Scotland Formation
Stratigraphic range: Devonian
Exposure of New Scotland Formation in John Boyd Thacher State Park, New York
Type	Geologic formation
Unit of	Helderberg Group
Underlies	Becraft Formation
Overlies	Kalcberg Formation
Thickness	60-140 feet
Lithology
Primary	Limestone
Other	Shale
Location
Region	Eastern New York State
Country	United States

The New Scotland Formation is a Lower-Devonian age geologic unit part of the Helderberg Group. The Helderberg Group represents units deposited by shallow marine environment sediments. At the time, what is now North America, as well as Ireland, Greenland, and parts of Russia, were part of the Laurentia supercontinent and New York was largely covered by shallow seas. These seas were warm and tropical since the continent was located near the equator. Laurentia, from 408 – 387 million years ago, collided with the European continent in an event known as the Acadian Orogeny that is partly responsible for the Appalachian Mountains present today. The erosion of sediments from these newly formed mountains were deposited into the shallow sea basin, known as the Appalachian Basin, now represented by the units of the Helderberg Group.

Throughout the time frame represented by the deposition of the Helderberg Group units, this shallow sea was undergoing fluctuations in depth, which affected the marine environment and life that can be found in the various units. The New Scotland Formation paleoenvironment is representative of a sub-tidal zone where, largely protected from the high wave energy of tidal and beach zones, diverse and abundant marine life would have found hospitable living conditions.

Outcrops in the Hudson Region of New York where the unit is best observed include Route 9 in the town of Coxsackie, Route 23 west of Catskill, and Route 199 in Kingston. The bedding thickness ranges from 60 feet thick in Scoharie County, New York, to 140 feet in northwest New Jersey.

Rock Type and Sedimentary Structures

The New Scotland Formation is composed of interbedded calcareous shales, chert, and fine to medium-grained argillaceous limestones.

The New Scotland Formation, as well as the underlying Kalcberg Formation, also contains several beds of clay-rich K-Bentonites designated the "Bald-Hill K-Bentonites." These k-bentonites derived from volcanic tephra that represents explosive volcanic history resulting from the Acadian Orogeny. These beds have been recorded widespread from eastern New York region southward to Virginia.

The New Scotland Formation typically weathers to a gray/brown coloring, in part due to the high pyrite content within the bedding. Because the unit is fissile and clay-rich, it has in some areas eroded and made fertile land suitable for grazing and agriculture.

Paleoenvironment

Brachiopods in the New Scotland, Kingston, NY

The New Scotland Formation contains diverse fauna, including trilobites, brachiopods, crinoids, rugose corals, and other invertebrates, indicating that the ocean environment at the time had normal conditions with regards to salinity, temperature and ph, as paleoenvironment "indicator" organisms such as brachiopods are known to only have been able to survive in non-extreme environments. Over 300 species of invertebrates have been found to date within the New Scotland Formation.

The facies of the Helderberg Group with their corresponding depositional environment. Note the deepening sequence moving from left to right.

The subtidal location of the New Scotland is suggested by the fossils present and presence of interbedded shales, chert, and argillaceous limestone.