The Age and Development of the Provincelands Hook, Outer Cape Cod, Massachusetts

The Provincelands Hook, an area of marshes and dunes, was built out from the northern end of the glacial deposits of Outer Cape Cod. The hook, a wedge 60 m at its thickest, of marine, beach, and dune material, rests in part on Tertiary Coastal Plain sediments that are probably only an isolated patch on the crystalline basement. About 18,000 years ago, when late Tazewell ice melted away from the region of present day Cape Cod, the Gulf of Maine was filled with ice, and Georges Bank was above sea level. Between 18,000 and 6,000 years ago, sand that eroded from the coast was moved along the east side of Cape Cod from north to south, where it accumulated as a part of the sand wave complex southeast of the cape. Waves from the east and southeast that would have tended to move sand northward along the Cape were blocked by Georges Shoals and Nantucket Shoals. By 6,000 years ago, sea level had so risen that deeper water over Georges Bank permitted more waves to reach Cape Cod from the east and southeast. The dominant direction of littoral drift which had been to the south, then received a strong north component and material moved northward, accumulating to form the Provincelands Hook. Based on14Cdates and other evidence, the hook formed between 6,000 years ago and the present and is still growing. Shoreline reconstructions are guided by14Cdates, well information, regional topography, and known behavior of hooks. It is noted that hooks are characteristic features of Cape Cod spits and tend to trap lakes behind them. The depressions containing lakes in the modern Provincelands are interpreted as low areas trapped behind hooks. A change in the growth habits of spits is thought to have taken place about 2,000 years ago, coinciding with the abrupt decrease in the rate of rise of sea level.