CTgeo
This series of slides illustrates how glaciers affected the landscape of Connecticut.

Click on the image for a larger view

RalphsSlide29.jpg (52625 bytes) Glaciers had an important influence on our land surface.  As great sheets of ice moved over our hills, they exploited the N-S valleys and carved away rocks that were weak and fractured.
RalphsSlide30.jpg (91298 bytes) This map shows the extent of the glaciers about 20,000 years ago.  Most of Canada and Greenland were covered, as well as New England.
RalphsSlide31.jpg (57148 bytes) Here is a map of the ice in our region.  The continental glacier covered Mt. Washington in New Hampshire (6018 feet).  This ice sheet entered Connecticut about 26,000 years ago, reached its maximum about 21,000 years ago, and was melted out of the state by 15,500 years ago.
RalphsSlide32.jpg (37111 bytes) The glaciers also covered the state earlier during the Ice Age, about 150,000 years ago, and many people think that they completely changed the topography.  In fact, the ice modified features already present.
RalphsSlide33.jpg (52431 bytes) As the ice moved southward, it deepened valleys and rounded hills.  The pre-existing N-S grain of the land was preserved and accentuated.
RalphsSlide34.jpg (51151 bytes) This mechanism is evident in modern glaciers, such as this one in Alaska where the rock surface (right side) is being rounded.
RalphsSlide35.jpg (34924 bytes) As the ice rounds off the hills, it picks up the broken rock fragments and other sediments.
RalphsSlide36.jpg (76342 bytes) Here is some recently-eroded rock material in Alaska.
RalphsSlide37.jpg (75880 bytes) In Connecticut, this sedimentary rock in the central lowland shows how harder sections were rounded while less-resistant rock was gouged out.  This happened at small scales like this as well as in major valleys.
RalphsSlide38.jpg (35315 bytes) Glacial plucking on the south sides of hills also influenced the shaped of the land, and provided rock shelters for paleo-North Americans.
RalphsSlide39.jpg (146595 bytes) This topographic map shows a glacially-plucked hill in Deep River.  The contour lines are closer together on the south side of the hill, showing a steeper slope.
RalphsSlide40.jpg (79900 bytes) The ice moved toward the viewer over this hill.  You can see how the plucked hillside could become an overhang and shelter for a weary traveler.
Next page: Ct. glaciers continued (to be added)
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