MD 220px-Map of USA MD

Rockhounding Maryland

Maryland is a good state for rockhounding.  Maryland has lots of fossils and is famous for its Miocene shark teeth.  In addition, dinosaurs thrived in what is now Maryland from the Late Triassic period to the Cretaceous, 228 million to 65 million years ago.


State Rocks, Gemstones, Minerals, Fossils, & Dinosaurs

Rockhounding Tip:  Knowing state rocks, gemstones, minerals, fossils, and dinosaurs often can be very useful information for rockhounders.  Ordinarily, states with significant mineral deposits, valuable gemstones, fossils, or unusual or significant rock occurrences will designate an official state mineral, rock/stone, gemstone, fossil, or dinosaur to promote interest in the state’s natural resources, history, tourism, etc.  Accordingly, such state symbols often are a valuable clue as to potential worthwhile rockhounding opportunities.

Maryalnd - Gem Patuxent River stone

Patuxent River Stone

State Gemstone:  Patuxent River Stone (2004)

Maryland designated the Patuxent River stone as its official state gem.  Proponents have suggested that the Patuxent River stone is agatized dinosaur bone.  Others, however, believe that it is neither agate or dinosaur bone and that it is common quartzite.

Maryland - Fossil

Ecphora gardnerae gardnerae (Wilson)

State Fossil:  Ecphora gardnerae gardnerae (Wilson) (1994) replacing Ecphora quadricostata (1984)

In 1984, the Maryland State Assembly passed a resolution designating Ecphora quadricostata as the official state fossil.  The Ecphora was a small snail that inhabited the Chesapeake Bay 12 to 5 million years ago.  An Ecphora shell found in St. Mary's County about 1685 was one of the first North American fossils illustrated in European scientific works.  It was first described in 1770 in the scientific publication Historiae Conchyliorum by Martin Lister.  Ecphora gardnerae was originally thought to the same species as Ecphora quadricostata. The two snails, however, were later declared to be separate species.  Accordingly, in October 1994, the State Assembly designated Ecphora gardnerae gardnerae (Wilson) as the state’s official fossil.  This actually is the same fossil snail that was first designated by the Maryland General Assembly in 1984, but there has been a name change.  The legislature's action in 1994 was in response to a name change by the scientific community.  The previous name was Ecphora quadricostata.  Changes in nomenclature are nothing new for Ecphora (or for most fossils, for that matter).


Maryland - Dino Astrodon

Astrodon johnstoni

State Dinosaur:  Astrodon johnstoni (1998)

Maryland designated Astrodon johnstoni as its official state dinosaur in 1998.  Astrodon johnstoni lived during the early Cretaceous period, between 130 million and 95 million years ago.  Astrodon means "star tooth" and derives from the fossils found in 1858 by Philip Tyson, then Maryland's State Agricultural Chemist.  His discovery of two teeth in the Arundel Clay near Muirkirk in Prince George's County was one of the earliest dinosaur finds in this country and the first in Maryland.  Tyson gave the teeth to a local doctor and dentist Christopher Johnston, who sliced a tooth into cross sections, discovering a star pattern.  In his 1859 article for the American Journal of Dental Science, Dr. Johnston called the species Astrodon.  Astrodons were sauropods (lizard-foot) of the Saurischian order (lizard-hip).  These large dinosaurs weighed up to 20 tons.  They had small heads, long necks, and long tails.  Strong, solid legs supported their rounded bodies.  Adult Astrodons could be 50 to 60 feet long, and more than 30 feet tall.  They were herbivorous, probably feeding on trees, ferns, and other plants.

Rockhounding Resources

State-specific rockhounding books (including the books listed here as well as other books), regional rockhounding site guides, and other helpful rockhounding resources are identified - by category - in the Books & Gear section of Gator Girl Rocks with a link to the Gator Girl Rocks Amazon Store where you may easily browse selected resources and securely place an order.  Your order will benefit Charity Rocks!

Geological Survey Map - Maryland

Maryland Geological Survey
Excellent collection of resources.


Maryland Minerals
Useful website that includes over 100 images of a wide variety of mineral specimens collected in Maryland as well as other resources.


Map - Fossil Collecting Sites

Maryland Geological Survey, Fact Sheet No. 7, Fossils in Maryland Counties - Map with county-specific fossil occurrences.  Does not show exact locations, but is a good reference resource.


  • Jasper Burns, Fossil Collecting In the Mid-Atlantic States (1991).
  • J.D. Glaser, Collecting Fossils in Maryland (Rev. ed., 1995).
  • John Means, Roadside Geology of Maryland, Delaware, and Washington DC (2010).
  • Floyd & Helga Oles, Eastern Gem Trails (1967).
  • James Martin Monaco & Jeannette Hathway Monaco, Fee Mining & Mineral Adventures in the Eastern U.S. (2d ed. 2010).
  • Kathy J. Rygle and Stephen F. Pedersen, Northeast Treasure Hunter's Gem & Mineral Guide (4th ed. 2008).

Museums of Interest to Rockhounders

Museum - Calvert Marine Museum

Calvert Marine Museum
Solomons, Maryland

The museum exhibits include original fossils of all the known groups of sea shelled animals that occur in the Miocene deposits of Calvert Cliffs, as well as the remains of sharks, fish, turtles, crocodiles, birds, whales, and land animals from this prehistoric time.  In addition, the museum has wonderful resources such as a fossil identification guide.  Why visiting my aunt and uncle, we also visited the museum.


Places to Visit - Interesting Sites To See

Calvert Cliffs State Park
Calvert County, Maryland
The massive cliffs from which Calvert Cliffs State Park was named dominates the shoreline of the Chesapeake Bay for thirty miles in Calvert County and were formed over 15 million years ago when all of Southern Maryland was covered by a warm, shallow sea.  When the sea receded 25 – 20 million years ago, marking the end of the Miocene period, cliffs were exposed and began eroding.  Today these cliffs reveal the remains of prehistoric species Including sharks, whales, rays, and seabirds that were the size of small airplanes.  The fossilized remains of hundreds of species of plants and animals occur here.



Dinosaur Park
Laurel Maryland
Dinosaur Park features a rare deposit of fossils from the Early Cretaceous period about 110 million years ago.  The Park is part of a geologic formation called the Muirkirk Deposit that consists of sediments and clays that occur south of Washington D.C. to north of Baltimore.  Here, paleontologists (as well as supervised members of the public) have unearthed fossilized bones of several kinds of dinosaurs, early mammals, and fossils of trees and early flowering plants.

Rockhounding Sites for Children & Families

Miocene Fossils
Bay Front Park – Chesapeake Bay, Northern Calvert County, Maryland
Bay Front Park (formerly known as Brownie’s Beach) is located on Route 261 at the northern end of Calvert County, immediately south of the town of Chesapeake Beach.  This site is accessible by foot only during low tide; at high tide, the water extends to the base of the cliffs. The exposure here is in the Calvert Formation.  Obviously, for your own safety, do not dig in the cliffs.


Miocene Fossils
Breezy Point Beach – Chesapeake Bay, Maryland
Breezy Point Beach is located at the end of Breezy Point Road just off Route 261.


Miocene Fossils
Matoaka Cottages/Beach Cabins – Chesapeake Bay, Maryland
Matoaka Cottages/Beach Cabins is located just east of St. Leonard off of Calvert Beach Road.  Although this is private property, the owners have allowed access to the beach and cliff area for a modest parking fee.  Here too, digging in the cliffs is not permitted. The beach is wide enough here to allow access during high tide, but collecting is usually better at low tide.


Shark Teeth (MD) 2005

Miocene Shark Teeth that I found when I was four years old

Miocene Fossils
Calvert Cliffs State Park – Chesapeake Bay, Maryland
Calvert Cliffs State Park is located about four miles north of Solomons on Route 4.  It has nature trails through a wooded park leading to the beach.  The beach (and fossil site) is a two mile hike from where you park your vehicle.  Mom and dad made me walk (both claiming that the hike was only 1.8 miles rather than 2 miles) … both ways … in the hot summer heat … and tried to distract my four-year old body by playing games.  At least dad carried my fossils for me.  A section of Calvert Cliffs lies immediately north of the end of the trail.  As a safety measure, however, in the 1980s the Maryland Department of Natural Resources closed the beach along the cliffs because of cliff collapses.  Accordingly, collecting is restricted to a small beach area in the area where the service road ends.  Best collecting is usually after a storm, because the supply of shells and other fossils is replenished.  Low tide is a better time than high tide to look for fossils along the beach because more beach is exposed.

Miocene Fossils
Flag Ponds Nature Park – Chesapeake Bay, Maryland
Flag Ponds Nature Park provides access (on a seasonal basis) to its beach.


Shark Teeth 3 (MD) 2005 - Zoe & William

My cousin and me - collecting fossilized shark teeth when I was four

Miocene Fossilized Shark Teeth
Chesapeake Bay - 
South of Calvert Cliffs


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