MARINGEOLOGI OG GLACIOLOGI
MOLLUSC RESEARCH, OVERVIEW

	Research team Kaj Strand Petersen - ksp@geus.dk
The clam Donax vittatus

Introduction
The molluscs are one of the most diverse and largest of all the phyla of the animal kingdom. They are found in most of the earth's environments from the deepest ocean abysses to the dry deserts. Molluscs vary from slow, shelled Pelecypods to the quick, fleshy squids. The molluscs include Cephalopods (ammonites, nautils, belemnites, squids, and octopus), Gastropods (snails), Pelecypods (bivalves), Scaphopods (tusk shells), Chitons, the extinct Hyotithids, and Monoplacophora. The study of molluscs is called malacology.

Gastropoda (meaning stomach footed) are the most various and wide ranging of all the molluscs. They are found palaeontologically and through the present in fresh and marine waters, in the ground, on land, in trees, and on mountains. They vary from large, shelled whelks to small, fleshy slugs. Gastropods have existed since the Cambrian Period but they expanded greatly throughout the Mesozoic and Cenozoic Eras. Gastropods include snails, whelks, limpets, periwinkles, and slugs.

Pelecypoda, or bivalves, are also found on land in fresh water, and in marine environments. They contain two valves with the body in between. Bivalves have been around since the Cambrian and include clams, oysters, scallops, and mussels.

Research
The department's mollusc research is mainly concentrated on marine bivalves and univalves.

• Much of the work is on environmental changes such as sea level changes and climate fluctuations as seen from the studies of Molluscs
• Further studies on aspects of geology, ecology and evolution of particular species are also taking place from the Arctic to the Lusitanian region of the Atlantic

Relative sea level rise demonstrated by mollusc fauna in the
Skagerrak-Limford region, Northern Denmark ( Petersen, 1981
C-14 dates on various levels indicate an Early Holocene transgression around 9000 to 8000 BP.
At 8500 BP the transgression reached a maximum of 3 m above present-day sea-level.
"THE CURVE DEMONSTRATES THE MOST ERECTED SEA SNAKE EVER SEEN" (Blume, chairman at the meeting in Texel (late 1970'ties)

The Holocene coastal development of Skagen Spit in Northern Jutland, Denmark. The sampling data of peat ( Martørv ) along the west coast of the Skagen Spit, with dating in calendar years BP and matching elevation of beach ridge. The K-NOS from the Copenhagen Carbon-14 Dating laboratory. (see Petersen, 1991

Did American clams sail to Europe on Viking Ships? (National Geographic, April 1993)
see Petersen et al., 1992

Geographical distribution of Macoma balthica (Linné) (see Símonarson et al., 1998

Structural analysis of the region around Kato Vassiliki showing the best-fit-great-circle and fold axis orientation ( Petersen, 2000



Sketch drawn from the hill of Haghia Tridha towards the east showing a crescent shaped island in the sea which was revealed to be part of the Flysch,
and the mollusc Cerastoderma glaucum (Poiret, 1789) which was one of the ancient seafood favorites for those who once lived there ( Petersen, 2000

Other Websites

• European Quaternary Malacologists ( EQMal
• International Union for Quaternary Research ( INQUA

References
Petersen, K. S., 1981: The Holocene marine transgression and its molluscan fauna in the Skagerrak-Limfjord region, Denmark. Spec. Publ. int. Ass. Sediment, 5, 497-503

Petersen, K. S., 1991: Holocene coastal and faunal development of the Skagen Odde, Northern Jutland, Denmark. In: Firth, C. R., and Smith, D. E., (guest eds): Protection and Evolution of Sea Coasts. Quaternary International, 9 : 53-60.

Petersen, K. S., Rasmussen, K. l., Heinemeier, j., & Rud, N., 1992: Clams before Columbus? Nature 359 , 679

Petersen, K. S., 2001: Late Quaternary environmental changes recorded in the Danish marine molluscan faunas. Tome 1-3. (see abstract

Rasmussen, K. L., and Petersen, K. S., in press: Characterizing the Sediments from the last Drainage Event of the Baltic Ice Lake . Submitted to Boreas, 5-OCT-2000

Kaj Strand Petersen - ksp@geus.dk
Feel free to send e-mail for more information.

Edited by:
Niels E. Poulsen, GEUS