| Arundel Formation | |
|---|---|
| Stratigraphic range: | |
 Outdoor excavation on an exposed portion of the Arundel clays at Dinosaur Park at Laurel, Maryland, USA | |
| Type | Geological Formation |
| Unit of | Potomac Group |
| Underlies | Patapsco Formation (Unconformity) |
| Overlies | Patuxent Formation |
| Thickness | up to 125 feet (40 m)[1] |
| Lithology | |
| Primary | Clay |
| Other | Siderite nodules |
| Location | |
| Region |  Maryland, Washington D. C. |
| Country | United States |
| Type section | |
| Named for | Anne Arundel County, Maryland |
| Named by | W. B. Clark, 1897[1] |
The Arundel Formation, also known as the Arundel Clay, is a clay-rich sedimentary rock formation, within the Potomac Group, found in Maryland[2] of the United States of America. It is of Aptian age (Lower Cretaceous). This rock unit had been economically important as a source of iron ore, but is now more notable for its dinosaur fossils. It consists of clay lenses within depressions in the upper part of the Patuxent Formation that may represent oxbow swamp facies.[3] It is named for Anne Arundel County, Maryland.[4]
- ^ a b Clark, W.B., 1897, Outline of present knowledge of the physical features of Maryland: Maryland Geological Survey Volume Series, v. 1, pt. 3, p. 172-188. [1]
- ^ "Geologic Map Legends". Coastal Plain Rocks and Sediments. Maryland Geological Survey. Archived from the original on 26 May 2011. Retrieved 27 June 2011.
- ^ Kranz, Peter M. (1998). "Mostly dinosaurs: a review of the vertebrates of the Potomac Group (Aptian Arundel Formation), USA". In Lucas, Spencer G.; Kirkland, James I.; Estep, J.W. (eds.). Lower and Middle Cretaceous Terrestrial Ecosystems. New Mexico Museum of Natural History and Science Bulletin 14. pp. 235–238.
- ^ "Geologic Unit: Arundel". National Geologic Map Database. USGS.