Fossil Collecting in the Calvert Formation near UMD
Calvert Cliffs State Park, MD
Fossil Hunting - A hike of 2 miles can be taken from the parking lot,
along an unimproved trail to the cliffs/beach area. Visitors may hunt
for fossils on the open beach area and keep what they find. Because
of the constant erosion of the cliffs, access to the cliffs is no longer
permitted.
http://www.dnr.state.md.us/publiclands/southern/calvertcliffs.asp The Calvert Formation
During the middle of the MIOCENE epoch, 10 to 20 million years ago, the Atlantic ocean covered Southern
Maryland. At times the sea spread as far west as the present site of Washington, D.C. Rivers flowing from the
Appalachian mountains to the Miocene sea carried mud and sand which built up the layers of sediments now
exposed as cliffs along the western shore of the Chesapeake Bay.
As present-day rain and and waves erode the Calvert Cliffs, new fossils are exposed daily. The vast majority of
these fossils are the shells of clam and snail species that lived in this warm shallow ocean. A diversity of shark
and stingray teeth are also fairly common. Sometimes, the remains of fish, turtles, crocodiles, oceanic birds,
extinct whales, long snouted dolphins, seals, and sea cows are also discovered. Since the sediments were
accumulating in a marine environment, the remains of land animals are much less common. Nevertheless,
occasionally parts of Miocene peccaries, camels, horses, elephants, and rhinos among others, are found.
Text from http://www.calvertmarinemuseum.com/paleontology.htm
Fossils Found in the Calvert Formation
Chesapecten Nefrens
Bivalve
Extinct Scallop
Ecphora sp.
Extinct Gastropod
Maryland State Fossil!
Mammal Vertebrae
A wide variety of sharks teeth can be found.
Photos from website: http://www.fossilguy.com/sites/calvert/index.htm
Visit this link for more photos of different types of fossils to search for.
Miocene and the Middle Miocene Extinction
The Miocene is a geological epoch of the Neogene Period and extends from about 23.03 to 5.332 million years
ago (Ma). The earth went from the Oligocene Epoch through the Miocene and into the Pliocene as it cooled into
a series of Ice Ages. The Miocene boundaries are not marked by a single distinct global event but consist rather
of regional boundaries between the warmer Oligocene and the cooler Pliocene.
The plants and animals of the Miocene were fairly modern. Mammals and birds were well-established. Whales,
seals, and kelp spread. At the end of this epoch, the Himalayas started to rise.
The term Middle Miocene disruption, alternatively the Middle Miocene extinction or Middle Miocene
extinction peak, refers to a wave of extinctions of terrestrial and aquatic life forms that occurred around the
middle of the Miocene Epoch, c. 14.8 to 14.5 million years ago, during the Langhian stage of the Miocene.
The Earth's climate has been cooling for the last 50 million years in a trend punctuated by three steps. Higher
rates of cooling occurred during the late Eocene–early Oligocene (c. 34 Ma), the middle Miocene (c. 14 Ma),
and the late Pliocene (c. 3 Ma). The step at 34 Ma is associated with the onset of continental glaciation in
Antarctica, and that centered on 3 Ma registers the expansion of Northern Hemisphere ice sheets. The midMiocene step, often referred to as the middle-Miocene climatic transition (MMCT), is the least understood, with
significant questions surrounding its timing, style, and fundamental cause. This major and permanent cooling
step, occurring between 14.8 and 14.1 Ma, is associated with increased production of cold Antarctic deep
waters, cooling of the Southern Ocean, and a major growth of the East Antarctic ice sheet. A Middle Miocene
delta 18O increase, that is a relative increase in the heavier isotope of oxygen, has been noted in the Pacific, the
Southern Ocean and the South Atlantic (Miller, K G., R. G. Fairbanks (1983). "Evidence for Oligocene−Middle
Miocene abyssal circulation changes in the western North Atlantic". Nature 306 (5940): 250–
253.DOI:10.1038/306250a0).
Some suggested causes for Middle Miocene extinction have been the Nördlinger Ries bolide impact (located in
western Bavaria, Germany) and volcanoes in African Rift Valley.