![[photo, Maryland Geological Survey, Kenneth N. Weaver Building, 2300 St. Paul St., Baltimore, Maryland]](/msa/mdmanual/21dnr/images/1198-1-1777b.jpg)
Maryland is made up of six physiographic provinces, or regions where the geology and climate make the land different from adjacent areas. These provinces include the Appalachian Plateaus; Ridge and Valley; Blue Ridge; Piedmont; Atlantic Coastal Plain; and the Atlantic Continental Shelf.
Appalachian Plateaus Province. The Appalachian Plateau lies in Western Maryland, stretching across Garrett County and western Allegany County. It holds siltstone, shale and sandstone, as well as some areas of coal.
Maryland Geological Survey, Kenneth N. Weaver Building, 2300 St. Paul St., Baltimore, Maryland, April 2007. Photo by Diane F. Evartt.
Blue Ridge Province. The Blue Ridge Province, mainly in western Frederick County, is made up of quartzite, gneiss, and volcanic rock.
Piedmont Province. The Piedmont Province covers central Maryland counties including Frederick, Carroll, Montgomery, Howard, Baltimore, and Harford counties, and extends into Baltimore City and Cecil County. It includes gneiss, schist, quartzite, marble, slate, limestone, dolomite, shale, gold, siltstone, and volcanic rock.
Atlantic Coastal Plain. The Atlantic Coastal Plain is the largest physiographic province in Maryland. It encompasses the whole Eastern Shore, all counties bordering the Chesapeake Bay, and Southern Maryland, including Prince George's, Calvert, Charles and St. Mary's counties. It is made up of gravel, clay, silt, sand, and some iron ore.
Atlantic Continental Shelf. The Atlantic Continental Shelf, which lies offshore, contains sand, silts, clay, and gravel.
![[photo, Cavern, Boonsboro, Maryland]](/msa/mdmanual/37mun/boonsboro/images/1198-1-09958c.jpg)
![[photo, Cavern, Boonsboro, Maryland]](/msa/mdmanual/37mun/boonsboro/images/1198-1-09960c.jpg)
At least 53 caves are found in Maryland. Most are in the western region of the State. They hold high concentrations of limestone and marble.
Many of the rocks in Maryland contain fossils, or the preserved remains of animals or plants. These include shark's teeth, shells, arthropods, and even dinosaurs. The Astrodon johnstoni is Maryland's State Dinosaur.
In Maryland, the formal study of geology originated with the first State Geological Survey, which began work in 1834. Its historical evolution led to the Maryland Geological Survey, which functions today within the Department of Natural Resources.
Caverns, Boonsboro, Maryland, August 2019. Photos by Diane F. Evartt.
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