Happy PFF: Geology of Vermont

Welcome to Postcard Friendship Friday, hosted by Marie at the French Fractrice.

Frantic digging in my office drawers produced a few more geology postcards. This one is published by the Vermont Geological Survey. The bedrock of Vermont is mostly metamorphic rocks. Here, they have different colors depending on their age, PreCambrian or younger. The red blobs on the eastern side of the state are igneous intrusions, now exposed at the surface. With the swirls, the geology looks rather artistic.

A more detailed PDF of Vermont Geology is at http://www.anr.state.vt.us/DEC/GEO/images/gengeo52.pdf. (The file is over 9 mb in size - it may take a bit to download. Of course, if you want a SERIOUSLY detailed map and cross-sections, just go to http://www.anr.state.vt.us/DEC/GEO/centmap.htm.

Like the other New England states, Vermont has been affected by several mountain-building events in the distant past. However now it has beautiful green mountains and valleys with classic picturesque villages, churches, and farmsteads. To give you an idea, I suggest you look at the photos of John David Geery. I have no affiliation - just found these beautiful photos on the Internet.

And, you probably know that Ben and Jerry's Ice Cream started in Bennington Vermont.

Viridian

Happy PFF - Geology of Connecticut

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.

Happy Postcard Friendship Friday!
Viridian

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.

Happy PFF - Washington State Geology

Welcome to Postcard Friendship Friday, hosted by Marie, the French Fractrice.

First, I would like to apologize for the quality of this image. I sent this postcard off to a person in Thailand via Postcrossing, before I started this series of blog posts. Thankfully this person put the card up on their postcard wall, where I retrieved this image. So I do not have the card in front of me, to tell you about the details of the geology of Washington.

However: the first page of the teacher resources PDF http://www.dnr.wa.gov/Publications/ger_teacher_packet.pdf (published by the WA Dept. of Natural Resources) has a great map. Print it out and brighten up your office!

I can tell you though that the southern and central parts of the state, in various shades of orange and yellow, are underlain by thick layers of Columbia River basalt. This nice graphic from the US Geological Survey explains it well. The eruptions ended 6 million years ago. A rich soil has formed over much of this area, making it great for farming.

Not feeling too well today, so will sign off here. Happy PFF!

viridian

Tennessee Geology Postcard

Published by the State of TN, Dept. of Conservation, Division of Geology. Modified from the Geologic Map of TN, 1966.

Color coding in the legend is for the age of the bedrock under all the loose sediments and soil. Yellow and peach are the youngest rocks, followed by green Mesozoic rocks, and the older Paleozoic rocks. All these rocks are sedimentary: limestone, shale, sandstone claystone, and coal.

The far eastern part of the state is more mountainous, and is underlain by mostly igneous and metamorphic rocks, shown in bright red and burgundy. These rocks are resistant to erosion, so stand high over time. Just to the west is a band of bright pink rocks. This is the Valley and Ridge province. Some layers are resistant and form long ridges. Other rock layers are soft, and weather to form long, somewhat narrow valleys.

More information is at this webpage by Clay Harris.

viridian