Welcome to Postcard Friendship Friday, hosted by Marie at the French Fractrice.
This postcard of the bedrock geology of CT came out rather pale, I'm afraid. And, the original is back in my office so I can't walk you through the details!!! I found a few more of these geological postcards buried deep in a drawer, so I have a few more to share with you.
I can tell you that most of the bedrock on the east and west of CT is metamorphic, though of different types and ages, therefore the different colors on the map.
The yellow area with red squiggles in it is the Hartford Basin. This area is interesting for several reasons. According to Gil Hanson, a geologist at SUNY Stony Brook, "The Hartford Basin is one of the many rift basins along the east coast of North America that formed during the early stages of rifting of Pangea during the Triassic and Jurassic. The rifting of Pangea eventually led to the formation of the Atlantic Ocean. The Hartford Basin contains a thick sequence of stream and lake sediments and basaltic sills and lava flows all of which are well exposed."
(To see an animation of the breakup of Pangea, go to this website by Chris Scotese. Move your mouse over the animation on that page, click and hold the left mouse button, and slide your mouse sideways. Cool!)
The red parts are intruded sills and lava flows, now making ridges and hills running down this valley.
The stream and lake sediments in some cases preserved dinosaur footprints. These can be seen at Dinosaur State Park!
Here is something else I found out through Google (how did we live without this?). The Brownstone buildings of NYC and Boston are made from the Portland formation, quarried from this area of Connecticut. According to the website on this formation, "The prevalence of Portland sandstone for construction during this era lead to the term "brownstone" being synonymous with "rowhouse" in the northeastern US."
Would you like a copy of the Generalized Bedrock Geologic Map of Connecticut, in a 8.5 by 11 inch size? Only 25 cents! You may purchase it through the on-line store of the Connecticut Department of Environmental Protection, which also includes the Connecticut Geological and Natural History Survey.
And please remember the plight of the people of Haiti. That EQ epicenter was very close to Port-au-Prince, the major population center, and Haiti building codes, such as they are, cannot be compared to those of California. This EQ is as big as the Loma Prieta or Northridge EQ's, but much more devastating.