The Williamsport Sandstone is a sandstone geologic formation in West Virginia, Virginia, Pennsylvania, and Maryland. the formation includes the Cedar Creek Limestone member. Near Cumberland, Maryland it includes the Cedar Creek Limestone member. It preserves fossils dating back to the Silurian period.
The Greene Formation is a geologic formation in West Virginia, Ohio, Maryland, Virginia and Pennsylvania. It preserves fossils dating back to the Permian period.
The Chesapeake Group is a geologic group in Maryland, Virginia, Delaware, and North Carolina. It preserves mainly marine fossils dating back to the Miocene and Pliocene epochs of the Neogene period. This group contains one of the best studied fossil record of Neogene oceans in the world. Professional Paleontologists and amateur fossil hunters alike collect from this group intensely. The Calvert Cliffs stretch the length of Calvert County, Maryland and provide the best continuous stretch of the Calvert, Choptank, and St. Marys Formations. Ward (1985) recommended including the Old Church Formation in this group.
The Potomac Group is a geologic group in Delaware, Maryland, New Jersey, and Virginia. It preserves fossils dating back to the Cretaceous period. An indeterminate tyrannosauroid and Priconodon crassus, a nodosaurid, are known from indeterminate sediments belonging to the Potomac Group. The Potomac Group was initially believed to have been Late Jurassic in age by Othniel Charles Marsh but later studies, such as Clark (1897), have found that the Potomac Group is in fact Early-Late Cretaceous (Aptian-Turonian) in age.
The Frederick Limestone is a geologic formation in Maryland and Virginia. It preserves fossils dating back to the Cambrian period.
The Oranda Formation is a geologic formation in Virginia. It preserves fossils dating back to the Ordovician period.
The Rockdale Run Formation is a geologic formation in Maryland, Pennsylvania, Virginia and West Virginia. It preserves fossils dating back to the Ordovician period.
The Patapsco Formation is a geologic formation of varigated clays, sandy clays, and sand in Virginia, the District of Columbia, Maryland, Delaware, Pennsylvania, and in the subsurface of New Jersey. It preserves fossils such as plants and molluscs dating back to the Cretaceous period.
The St. Marys Formation is a geologic formation in Maryland and Virginia, United States. It preserves fossils dating back to the Miocene Epoch of the Neogene period. It is the youngest Miocene formation present in the Calvert Cliffs and is part of the Chesapeake Group.
The Choptank Formation is a geologic formation in Virginia and Maryland. It preserves fossils dating from the Miocene epoch of the Neogene period.
The Jennings Formation is a geologic formation in Maryland. It preserves fossils dating back to the Devonian period.
The Matawan Formation is a geologic formation in Maryland and New Jersey. It preserves fossils dating back to the Cretaceous period.
The Monmouth Formation is a geologic formation in Prince George's County, Maryland. It preserves fossils dating back to the Cretaceous period.
The Java Formation is a geologic formation in Kentucky, New York, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia. It preserves fossils dating back to the Devonian period. The formation comprises the Pipe Creek Shale, Wiscoy Sandstone Member in New York, and Hanover Shale Member except in Tennessee.
The Tomstown Dolomite or Tomstown Formation is a geologic formation in Maryland, Pennsylvania, Virginia and West Virginia. It preserves fossils dating to the Cambrian Period.
The Viola Formation is a geologic formation in Oklahoma. It preserves fossils dating back to the Ordovician period.
The Ouray Formation is a geologic formation in Colorado. It preserves fossils dating back to the Devonian period.
The Farisita Formation is a geologic formation in Colorado. It preserves fossils dating back to the Paleogene period.
The Maroon Formation is a geologic formation in Colorado. It preserves fossils dating back to the Permian period. It is the primary formation of sandstone that lends the vivid red color to the hills around Glenwood Springs, Colorado.
The Stockdale Shales is a geologic formation in England. It preserves fossils dating back to the Silurian period.
Maryland 
United States 
