Bedrock and Glacial History and Geomorphology of Long Island and

Southern Connecticut

By Drew Martzolf

Coastal Connecticut & Long Island• High economic importance• Home to millions of people• Significant ecological value• Current threats:– Coastal erosion– Rising sea levels– Pollution

Formation of the Continent

From: http://www.jamestown-ri.info/acadian.htm

Taconic orogeny

Formation of the ContinentAcadian orogeny

From: http://www.lisrc.uconn.edu/lisrc/geology.asp?p2=History&p3=glhct

Formation of the Continent

From: http://www.lisrc.uconn.edu/lisrc/geology.asp?p2=History&p3=glhct

Alleghenian orogeny

Glacial History• Manetto stage

– Manetto gravel fluvially deposited

• Jameco stage– Jameco gravel deposited in northeast of island

• Manhasset stage– Montauk and Hempstead Formations deposited

• Wisconsinan stage– Ronkonkoma moraine

From: http://pubs.usgs.gov/fs/FS-008-99/html/CT_fig04.html

Formation of Long Island Sound

Original postglacial basin was Glacial Lake Connecticut, dammed in by the moraines of Long Island; water drained to west. Rising sea levels allowed salt water to flood back into basin, followed by erosion to open access from the eastern end to the open ocean.