Glacial History of Cape Cod, Nantucket, and Martha’s Vineyard

Stefan Sandreuter ‘16

GE354

Outline

• Formation of Cape Cod, Nantucket and Martha’s Vineyard

• Regional Deposits

• Post-Glacial Holocene Processes

• Summary

Formation of Cape Cod, Nantucket and Martha’s Vineyard

• Three lobes of glacial ice

• Fluctuating Ice Front

• Evidenced by till overlying stratified drift; recessional moraines

Regional Deposits

• Types of deposits

• General Stratigraphy

• Age of Deposits– Cosmogenic Nuclide Dating

• Mineralogy

Cosmogenic Nuclide Ages

Martha’s Vineyard

Buzzard’s Bay

*Radiocarbon dates put glacial deposits between 24,000 and 21,500 years old.

Post-Glacial Holocene Processes

• Marine and Aeolian Processes

• Two periods of Holocene modification– 9,500 – 6,000 B.P– 6,000 B.P. to modern day

Summary

• Three lobes of ice

• Fluctuating ice sheet

• Nantucket and Martha’s Vineyard - terminal moraines of the Laurentide Ice Sheet

Summary

• Cosmogenic nuclide ages of ~23,000 and 19,000 years from Martha’s Vineyard and Buzzards Bay respectively

• Subarkose and quartz arenite sands from both outwash plains and beaches

• Constant marine and aeolian modification

Questions?