Thursday, October 8, 2009

Bedrock geology of Wisconsin PFF


With our lovely hostess Marie at Vintage Postcards. Her postcard and story this week ... Shocking!


Not so shocking: Bedrock Geology of Wisconsin

From the back: :An example of one of many maps available from the Wisconsin Geological and Natural History Survey. Write to the M.A.P.S. Office for a free list of publications.
Geological and Natural History Survey, 3817 Mineral Point Road, Madison, Wisconsin. "

Here in Wisconsin there are older flat-lying layers of sedimentary rocks of Devonian and Ordovician in age, but also some much older rocks. See the geologic time scale on this web page. There is also a PDF (handy when reading my blog ;-) )

Those purple and lavender rocks in northern Wisconsin are about 1000 million years old! The patches of orange are even older, about 2500 million years old! These rocks have been metamorphosed and folded - hard to escape that when you have been around so long.
There is an area in west-central Wisconsin that was not covered by ice during the last glaciation event in the Ice Ages. How do they know? because there are no piles of glacial sediments as there are in most parts of North America, and Northern Europe and Asia too. This is still pretty difficult to explain.
Catch up on your geology postcards:

Viridian

11 comments:

Snap said...

I get an education in geology when I visit and it's a pretty card!

Evelyn Yvonne Theriault said...

Lots of geology news this week, what with the triple earthquakes in the Pacific!
Evelyn in Montreal

Sheila said...

Yes, I'm metamorphosing and folding too! :) These cards are helping me so much with my American geography as well as geology.

MrCachet said...

You are not doing these in order of acceptance into the Union, so - DO MONTANA! And let me know when you do, so I can make an envelope from the image and send you one!

Melissa B said...

I will check Massachusetts, but Vermont is supposed to have quite a varied terrain, have you looked at there?

Great to see a post card blog! I have always loved them as they capture a slice of history and society in different times. I have lots more of the Quimper postcards framed in my dining room in groupings of costumes that are similar to the ones on my faience.

viridian said...

MrCachet:

I am trying to go generally from east to west, based on the postcards I have. (not completly though - I did Utah first!) Nebraska is next, then Montana, probably next Friday.

Christine Heycke said...

These are truly beautiful even if you don't understand the geology behind them. Your explanation makes it doubly interesting. Waiting patiently for Oregon and Washington...

Beth Niquette said...

THAT is a GREAT postcard! I've always been fascinated with geology. Wonderful and Happy PFF!

steviewren said...

That info ROCKS!

maryt/theteach said...

Wow! Thanks for all the geological info! How about new York State? :) Come visit me if you can! :)

Marie Reed said...

My Grandmother (who past away two weeks ago) grew up in Wisconsin makes this card especially wonderfully to see!. That connection makes this card especially wonderful to se:)

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