Trinidad Sandstone

The Trinidad Sandstone is a geologic formation in northeastern New Mexico and southeastern Colorado.^[1] It was formed during the Campanian Age of the Cretaceous Period and contains fossils.^[2]

Trinidad Sandstone
Stratigraphic range: Campanian PreꞒ Ꞓ O S D C P T J K Pg N
The Trinidad Sandstone forms a prominent band in the cliffs north of Raton, New Mexico, USA
Type	Formation
Underlies	Vermejo Formation
Overlies	Pierre Shale
Thickness	70–300 ft (21–91 m)
Lithology
Primary	Sandstone
Location
Coordinates	37.17°N 104.51°W / 37.17; -104.51
Region	New Mexico Colorado
Country	United States
Type section
Named for	Trinidad, Colorado
Named by	R.C. Hills
Year defined	1899
Trinidad Sandstone (the United States) Show map of the United States Trinidad Sandstone (Colorado) Show map of Colorado

Description

The Trinidad Formation consists of a massive fine- to very fine-grained arkosic sandstone some 70–300 feet (21–91 m) in thickness.^[1][3] It rests conformably on the Pierre Shale and is in turn conformably overlain by the Vermejo Formation.^[4][2]

The formation is interpreted as shore deposits marking the final regression of the Western Interior Seaway from northeastern New Mexico. It is correlative with the Fox Hills Sandstone and the Pictured Cliffs Sandstone.^[5]

Fossils

The formation contains trace fossils of Ophiomorpha and, in a few locations, Diplocraterion. "Ladders" of Diplocraterion are over 1 meter (3.3 ft) long in the lower part of the formation at Cerrososo Canyon.^[3]

Economic geology

There is potential for natural gas extraction from the Trinidad Sandstone. The gas originates in interbedded coal formations.^[6]

History of investigation

The beds making up this unit were originally included in Hayden's Raton Hills group in 1869. The name, Trinidad, was first applied by R.C. Hills in 1899, and W.T. Lee (1917) further refined the definition to include only Hills' "Upper Trinidad".^[1]