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Competency Area 1: Basic Soil Properties

PO 2. Understand the processes of soil formation in the Northeast.

All of the New England states and most of New York were once covered by huge expanses of snow and ice, like Antarctica today. These glaciations have had great effect on the soils we find in the Northeast. We know of four glaciations (in chronological order): the Nebraskan, the Kansas, the Illinoisan, and the Wisconsin glaciations. When large amounts of snow and ice accumulated the ice started to move due to gravity. At the bottom of the ice, rock was picked up. This rock would scrape along the bottom of the ice, be pushed into it, and grind up the rock below. At the end of the ice age, the ice melted and dumped everything in it in-situ, as well as caused massive runoff that caused erosion and sedimentation.

The five factors that determine soil formation are:

  1. Parent Material
  2. Climate
  3. Relief
  4. Biota
  5. Time

The influence of forest vegetation is clearly seen in soils of the Northeast. Forest soils typically do not have high contents of organic matter, probably due to the limited turnover of the root systems of trees. This contrasts sharply with the prairie soils with high organic matter prevalent in the Midwest which developed under perennial grass vegetation. Further, some tree species, especially coniferous ones, release significant amounts of organic acids from their leaves upon decomposition. These acids can dissolve organic matter, aluminum and iron oxides and wash these down into the soil profile. This leaves a leached layer (gray or white) near the soil surface, under a dark organic surface layer. The organic acids and aluminum and/or iron oxides will be deposited below the leached ('E') horizon forming a dark and sometimes orange colored layer.  These soils are most common in sandy soils, especially in the outwash plains common in the Northeast.