Ralph Lewis's Geology of Connecticut Landscapes

This series of slides illustrates the rifting of Pangaea to create the modern Connecticut Valley landscape.

Click on the image for a larger view

A satellite view of New England shows the ancient north-south folding and rifting.

Let's look at the rifting first. This cartoon image shows the location of Connecticut in the rift zone of Pangaea.

As Africa separated from North America, a series of rift valleys formed (including the Hartford basin labeled by H), shown here in red.

Earlier folding caused a N-S weakness, and the crust failed in Connecticut along that direction as rifting proceeded.

Mesozoic sediments and lava flows in this block diagram of the Connecticut Valley were originally horizontal. As faulting tilted the rocks downward to the east, the asymmetric ridges came into existence.

Here is a view of the lava flow (basalt) ridges from the south.

The central Connecticut Valley, Proto-North America, Avalonia, etc. are reflected in the shapes of the land surface.

The landscape components of Connecticut include the N-S basalt ridges, Mesozoic sedimentary rocks, and the eastern and western terrane uplands flanking the central valley.

The geological components of Connecticut are arranged in terranes, which are sections of the earth's crust that have their own geological history.

The geological bedrock map of Connecticut arranges the different rocks that make up Connecticut according to the terranes. The rock units show the common N-S trends and faults, which are also directions of "weakness" that were exploited by glaciers that covered Connecticut during the Ice Age.

Next page: the Ice Age

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	A satellite view of New England shows the ancient north-south folding and rifting.
	Let's look at the rifting first. This cartoon image shows the location of Connecticut in the rift zone of Pangaea.
	As Africa separated from North America, a series of rift valleys formed (including the Hartford basin labeled by H), shown here in red.
	Earlier folding caused a N-S weakness, and the crust failed in Connecticut along that direction as rifting proceeded.
	Mesozoic sediments and lava flows in this block diagram of the Connecticut Valley were originally horizontal. As faulting tilted the rocks downward to the east, the asymmetric ridges came into existence.
	Here is a view of the lava flow (basalt) ridges from the south.
	The central Connecticut Valley, Proto-North America, Avalonia, etc. are reflected in the shapes of the land surface.
	The landscape components of Connecticut include the N-S basalt ridges, Mesozoic sedimentary rocks, and the eastern and western terrane uplands flanking the central valley.
	The geological components of Connecticut are arranged in terranes, which are sections of the earth's crust that have their own geological history.
	The geological bedrock map of Connecticut arranges the different rocks that make up Connecticut according to the terranes. The rock units show the common N-S trends and faults, which are also directions of "weakness" that were exploited by glaciers that covered Connecticut during the Ice Age.
	Next page: the Ice Age
	Close this window to return to the main menu page