The Vermejo Formation is a geologic formation of Upper Cretaceous age which outcrops in the Raton Basin of northeastern New Mexico and southeastern Colorado.
The Vermejo Formation was originally named by W. T. Lee in 1913 in the American Journal of Science. In 1917, Lee described the formation more completely in USGS Professional Paper 101 (pages 51–55). The formation was described as a light gray, soft, friable sandstone and shale, which is carbonaceous in part, and may have coal seams or thin coal beds. The Vermejo Formation was about 375 feet (116m) thick at the type locality which is Vermejo Park in Colfax County, New Mexico.
The Vermejo Formation unconformably overlies the Trinidad Formation, and unconformably underlies the Raton Formation.