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