Tuesday, May 20, 2008

Some Geology Notes


  • LI reached present shape around 6,000 years ago

  • Wisconsinan glacier came to LI twice: 60,000 years ago and 21,000 years ago

  • Harbor Hill Morraine: Hilly ridge in the North stretching from Brooklyn Heights to Orient Point, named for Harbor Hill in Roslyn

  • This morraine has an outwash plain: Terryville Outwash Plain

  • Ronkonkoma Terminal Moraine: stretches from Brooklyn to Montauk

  • South of that is the Hempstead Outwash Plain

  • Ice claws from the glacier carved the inlets and harbors on the North shore

  • Except for some exposed bedrock in Queens, everything on the surface of LI was deposited by the glacier

  • The soil on the Morraines retains moisture and supports hardwood trees like Oak, Hickory, Chestnut and Tulip trees

  • Soil in the outwash plains does not retain as much moisture and supports softwoods pitchpine forrests

  • Dryness in the outwash plains make forrest fires more likely, some pine trees in the plains depend on fire to reproduce

  • Shade in the Morraines attracted deer and turkey, also predators like wolves, bears and cougars

  • On the extreme Eastern end of the island, some silt made the plains there more like the soil found in the morraines (windblown silt called loess settled there)

  • The Hempstead Plains, a 60,000 acre area, is the Eastern-most prarie in North America

  • It may have been created by Native Americans who burned trees and shrubs to aid hunting and farming, grasses grew there and the prarie formed

  • Grasslands of these plains provided grazing ground for livestock for generations

  • Barrier islands on South shore formed by Atlantic Ocean

  • Their protected waters provided food for natives and colonists

  • Early inhabitants (as far as 5,000 years ago) preferred to live near shores, rivers and streams

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