Happy PFF! The Mysterious Hanging Boulder

Thank you to our hostess Beth at The Best Hearts are Crunchy for hosting Postcard Friendship Friday. Click on the link to see who else is playing!

On the front: " The mysterious hanging boulder mystifies all who pass under.  Polar Caves, N.H."

On the back:  "Polar Caves, N.H., America's greatest Boulder Caverns.  A maze of caves and spectacular rock formations.  All caverns colorfully lighted.  Different from and [sic] caverns you may have seen.  Nothing like it on the American continent."

I love older tourist postcards like this.  Whether it's a giant dinosaur or jackalope, a big ball of string, or an odd piece of geology, I find it so funny.  Terribly funny, in all senses of the words.  Ken Brown has a good time making fun of these postcards.

Polar caves in Rumney NH is still there and still an active tourist location.  Its website is, of course, http://www.polarcaves.com/.  I browsed the photo album, and yes, the mysterious hanging boulder is still there.


viridian

Happy PFF: Yosemite

Reposting:


Thank you to our hostess Beth at The Best Hearts are Crunchy for hosting Postcard Friendship Friday. Today we are visiting the magnificent Yosemite National Park in California.

Giving credit where credit is due:

The back of this card says: "Works Progress Administration (WPA) circa 1939, Artist Unknown. Between 1935 and 1943 the WPA's Federal Art Project printed over two million posters in 35,000 different designs to stir the public's imagination for education, theater, health, safety, and travel. Due to their fragile nature only two thousand posters have survived. The National Park image shown here is also available in the original poster format from many National Park bookstores." Published by Ranger Doug Enterprises, Seattle, WA.

It's hard to believe that the first tourists arrived in the early 1860's to the "Incomparable Valley." Environmental degradation soon followed. According to the park website, "Parts of the landscape were exploited, spurring conservationists to appeal for protections. President Abraham Lincoln signed an 1864 bill granting Yosemite Valley and the Mariposa Grove to the State of California. John Muir helped spark the creation of Yosemite National Park in 1890." As long ago as Lincoln! I did not know that.

The image on our postcard this week is of one of the magnificent domes, made from glacial action and erosional action on the granite (actually granodiorite, technically) bedrock. The most famous is Half-Dome. Another is El Capitan. I believe the view on this postcard is El Capitan.

The hard way up Half-Dome is technical rock climbing up the sheer northwest rock cliff. The 'easy' way is a hike through the woods to the base of the east side (the back side so to speak) and then onto the rock itself with a total elevation gain of 4800 feet (1460 m). According to Wikipedia, the last 400 feet of nearly vertical climbing is up the rock between two steel cables used as handholds, raised on a series of metal poles. The cables are attached to the rock but the poles are not. Look at that photo of Half Dome in profile! No matter where you put the trail it's going to be tough, as you can see in the photo of people on the Cable trail (Pictures from Wikipedia).

Even with all this there can be crowds and up to 1000 people a day have hiked this trail. Therefore, permits are now required to hike this trail on Fridays, Saturdays, Sundays, and Federal holidays when the cables are up (usually Memorial Day through Columbus Day). See the National Park webpage for more information.

There is so much more to say about this park - the waterfalls, the geology, the ecology, the history... but I have a load of work to do!

News: Val won the give-away of these WPA poster cards! Congratulations Val!
 
Viridian

Happy PFF: Yosemite National Park

Thank you to our hostess Beth at The Best Hearts are Crunchy for hosting Postcard Friendship Friday.  Today we are visiting the magnificent Yosemite National Park in California.
Giving credit where credit is due:
The back of this card says: "Works Progress Administration (WPA) circa 1939, Artist Unknown. Between 1935 and 1943 the WPA's Federal Art Project printed over two million posters in 35,000 different designs to stir the public's imagination for education, theater, health, safety, and travel. Due to their fragile nature only two thousand posters have survived. The National Park image shown here is also available in the original poster format from many National Park bookstores." Published by Ranger Doug Enterprises, Seattle, WA.

It's hard to believe that the first tourists arrived in the early 1860's to the "Incomparable Valley."  Environmental degradation soon followed.  According to the park website, "Parts of the landscape were exploited, spurring conservationists to appeal for protections. President Abraham Lincoln signed an 1864 bill granting Yosemite Valley and the Mariposa Grove to the State of California. John Muir helped spark the creation of Yosemite National Park in 1890."  As long ago as Lincoln!  I did not know that.

The image on our postcard this week is of one of the magnificent domes, made from glacial action and erosional action on the granite (actually granodiorite, technically) bedrock.  The most famous is Half-Dome.  Another is El Capitan.  I believe the view on this postcard is El Capitan.

The hard way up Half-Dome is technical rock climbing up the sheer northwest rock cliff.  The 'easy' way is a hike through the woods  to the base of the east side (the back side so to speak) and then onto the rock itself with a total elevation gain of 4800 feet (1460 m).  According to Wikipedia, the last 400 feet of  nearly vertical climbing is up the rock between two steel cables used as handholds, raised on a series of metal poles.  The cables are attached to the rock but the poles are not.  Look at that photo of Half Dome in profile!  No matter where you put the trail it's going to be tough, as you can see in the photo of people on the Cable trail (Pictures from Wikipedia). 

Even with all this there can be crowds and up to 1000 people a day have hiked this trail.  therefore, permits are now required to hike this trail on Fridays, Saturdays, Sundays, and Federal holidays when the cables are up (usually Memorial Day through Columbus Day).  See the National Park webpage for more information.

There is so much more to say about this park - the waterfalls, the geology, the ecology, the history... but I have a vacation to plan for and a thunderstorm is coming on.  I'll be away on Friday so I won't be able to comment on your postings.  Beth will link in this post for me - thank you dear Beth!!!

And don't forget - if you like these postcards, please do enter my contest, in honor of post #99 for this blog.  The prize to the lucky winner is my set  of 10 unused WPA poster postcards, mailed to you - anywhere in the world!

Just comment on this post.  Do so by June 29 at 6 PM Eastern USA time.

Viridian

Happy PFF: Geology of Indiana

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

This week’s geology postcard is the bedrock geology map of Indiana. It is published by the Department of Natural Resources, Indiana Geological Survey at Indiana University, 611 North Walnut Grove, Bloomington In 47405

The state of Indiana is underlain by Paleozoic sedimentary rocks, Ordovician to Pennsylvanian in age. Note that the older rocks are in the east, and younger rocks in the west. These rocks are shale, siltstone, limestone and dolomite, indicating they were deposited in ocean water.

From The Tectonic Features of Indiana webpage:
“The younger sedimentary rocks that were deposited on top of this basement complex were formed in a setting of quiet marine and river waters. Much of this time the craton was covered by a large shallow sea, a so-called "epicratonic sea" (meaning literally "on" the craton). Sometimes land masses or mountain chains rose up on the distant edges of the craton and then eroded down, shedding their sand across Indiana. These sediments whether deposited in rivers or seas eventually compacted into the sedimentary rocks that cover the state today.”

See the bright pink pattern in central Indiana, looking like a tree branch, or perhaps a river valley with tributaries? It is indeed an old river system, the Teays River system. More on this below.

Covering the bedrock in most of Northern Indiana are glacial sediments, laid down by the Ice Ages.

From Freeze Frame: The Ice Age in Indiana by Anthony Fleming:
“As it crossed the landscape this first glacier completely changed the surface drainage that had taken millions of years to develop, damming up river valleys into lakes, diverting stream channels to the south, and in some cases completely filling up large valleys with sediment, leaving little record of their existence. The giant Teays bedrock valley system was one such victim. This valley system was the premier drainage way in eastern North America prior to glaciation, extending from its headwaters in the western mountains of North Carolina and Virginia to the Mississippi River in western Illinois. The gorge-like valley of this river was as much as 200 to 400 feet deep and crossed north-central Indiana between about Berne (Adams County) and Lafayette (Tippecanoe County). Today, there is virtually no trace at the modern land surface of the once giant river—only a deeply buried valley on the bedrock surface defined by various wells and test borings.”

Near Bloomington are many limestone quarries, most disused now. Indiana Limestone (or Bedford limestone) has been used as exterior stone of many US government buildings, college campus buildings, and the Empire State Building.
If you have seen the movie Breaking Away then you have seen the quarries, and Bloomington Indiana.

I think I am at the end of my geology postcard series. I have you have enjoyed it.

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 - Seismicity of Caribbean

Marie, the French Fractrice, has "Booger Hollow, Arkansans" on her blog for this week's Postcard Friendship Friday, but I picked this one out ahead of time.

An over sized postcard published by the US Geological Survey, it shows the Caribbean and surrounding areas and plotted in tiny dots (even on the original) are the locations or epicenters of 94 years of earthquakes. Coloring of the land indicates height above sea level (green: low elevation; browns: getting higher), and different shades of blue indicate ocean depths. (Pale color: less than 100 meters, deeper blues for deeper depths). The average ocean floor in the Atlantic and Pacific oceans is over 3 miles deep!

There are a number of plate tectonic boundaries in the Caribbean and one does veer right through Haiti. A 7.0 magnitude quake is a major one and in such a poor country..... This area is going to be suffering for years to come. I worry about 6 months from now, when the hurricanes start arriving.

The USGS has prepared a poster on the 7.0 Haiti earthquake. You can print out a large copy if you have access to a large-format printer, or you can print a smaller size. the link is http://earthquake.usgs.gov/earthquakes/eqarchives/poster/2010/20100112.php

One person has asked where I find all these postcards. Well, let's just say that if you go to conferences where the state surveys have a booth and they have promotional postcards.... you can build a great collection.

I have two more state geology postcards, for later weeks. Take care!

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

Postcard Friendship Friday - California Geology

A simplified Geologic Map of California, from the California Geological Survey, established 1880. Oversized postcard, 5 by 7 inches.

Red areas are intrusive granitic rocks, mostly Mesozoic in age. They hold up the great mountain ranges of CA including the Sierra Nevada and the Yosemite area, the Peninsular Ranges and the San Gabriels north of L.A. In the theme of Christmas, the dark green rocks are older metamorphic rocks, and the swath of yellow is the Great Central Valley, covered with recent sedimentary rocks. The lighter green areas closer to the coast are part of the Franciscan Complex, rocks of rather high pressure metamorphism that went down a subduction zone, came back up, and got stuck here because of the San Andreas Fault.

Here is a state with a lot of geology, and taxpayers who don't mind paying for the Geological Survey. Er, except maybe now, as CA is nearly out of money. As they note: "The CGS staff is dedicated to the fulfillment of our stated mission of providing information and advice to protect life and property from natural hazards and to promote a better understanding of California's diverse geologic environment" BUT "All CGS offices will be closed the first 3 Fridays of every month due to the furlough program mandated by the Governor."

Gold was discovered in the Sierra Nevada Mountains, starting the Gold Rush of 1849 - 1850. California has many other natural resources.

California has the major plate tectonic boundary of the San Andreas fault, and other minor faults. And plenty of earthquakes. How many?

Note that there are 638 earthquakes on this map, and all happened in the last week (!). Most were very small, and detected only by seismometers. The USGS and the CA Geological Survey spend a lot of time and effort on earthquake preparedness. This includes tsunami warning systems.

It's hard to believe it's been 20 years since the 1989 Loma Prieta quake, which stopped game 3 of the World Series.

Other San Andreas links:

Carrizo Plain National Monument

Wallace Creek area guide

Hayward fault: Slow fault creep in Hollister

National Parks and seashores in CA:

Death Valley

Yosemite

Point Reyes

Muir Woods

All of which I want to visit, some for the second or third time.

Viridian

Geology of Idado - PFF

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

I am NOT going out shopping on Black Friday. We are decorating for Christmas. Which has little to do with the state of Idaho, but that is the postcard for today.

This is standard sized postcard, published by the Idaho Geological Survey. After scanning it, I seemed to have misplaced it!

The Geology of Idaho is similar to the states around it - after all, geology does not stop at the state line. The pink color represents a huge intrusion of granite, now exposed at the surface. The green and olive colors represent sedimentary rocks, uplifted during mountain building, just as in Montana, and Nevada. The bright blue represents Columbia River basalts. The broad yellow is another basalt flow. This area has developed good soils for growing potatoes.

Time to go, the kids are fighting. Happy PFF!

Viridian

Geology of New Mexico -- PFF

This week I went through my unfiled papers drawer in my office and dug deep and found, yes, more geology postcards! After going through the west of the USA, we'll have to head east again for CT and VT. Anyway...
Welcome to Postcard Friendship Friday, hosted by Marie at the French Fractrice.

This is an oversized postcard (6 by 8 inches) published by the New Mexico Bureau of Mines and Mineral Resources, 801 Leroy Place, Socorro, NM. I have scanned it at a higher resolution than usual so there should be detail visible if you double-click on the image.

The back has a good summation of the general geologic history and so I will quote it here, with my comments in [ and ] brackets.

"The rocks of New Mexico reveal a long and complex of deposition, volcanic eruptions, structural deformation [due to plate tectonics as described in earlier posts], and climatic extremes -- from intensely folded Precambrian cores of mountain ranges more than 600 million years old to black basalts that flowed across the landscape as recently as 900 AD. White sand dunes today move slowly across the world's largest gypsum [a calcium sulfate mineral] desert, where waves of water once broke upon the shores of vanished lakes. New Mexico's extensive mineral and energy resources are a result of this colorful history -- petroleum and natural gas, coal, copper, uranium, gold, silver, molydenum [used for specialty steel] , lead, zinc, barite [a source of barium], fluorite [mined for fluorine, used in industry], gypsum [mined for drywall, aka sheetrock], perlite [see Wikipedia entry] , potash [used in fertilizer], and sand and gravel."
A Virtual Geologic Tour of New Mexico from the Bureau.

Major cities shown on the map are Farmington, Santa Fe (the capital), Albuquerque, Socorro, Las Cruces, and of course, Roswell.

Viridian

Geology of Nevada: Postcard Friendship Friday

I have already blogged about my Geology of Utah postcard (on July 3!), so it's time to move on to Nevada. Utah is to the east, Idaho to the north, California to the West. the large areas of orange to the north of Nevada are fairly young volcanic rocks that extend into Idaho. there are some orange blotches to the south too. Note the pink, purple and blue bands oriented north-south, with pale yellow in between. This is the Basin and range part of the North American continent.

[The following information is from a remote sensing tutorial published by NASA.]


Major C.E. Dutton, an early explorer of the American West, described these mountains as they appeared on a map as resembling "an army of caterpillars crawling northward out of Mexico".

Hmm, I see what he's saying. Below is a color - coded relief map (relief: the ups and downs of the landscape) of NV.

The mountains are uplifted parts of older continental crust. This area was being pulled apart, slowly, and the pieces in-between sank lower. The valleys are filled with a lot of sediment that has eroded from the ranges and partially filled them up. This is what the area looks like from the air.
[End quoting]
Some of these peaks are significant. Wheeler Peak in Great Basin National Park is about 13,000 ft (4000 m) tall. What little rain or snow there is falls on these peaks and so the heights are green with pine trees, even white with snow. It is quite different from the dry, hot, desert valleys in between!

There is a wonderful part of the East Humboldt Range where erosion had sculpted the ridges in amazing ways, and the ridge is so thin that there is a hole right through it! This, of course, is called the Hole-in-the-Wall (or Lizzie's Window), near Hole-in-the-Wall Mountain. Please see this website for hiking in the area. The photos are amazing, but copyrighted, so I am not going to reproduce them here.

Las Vegas is way to the south of the state. Many areas in the middle of the state are very sparsely populated. With renewed gold mining in some areas in the north, population has grown somewhat.
Much more detail from about.com: http://geology.about.com/library/bl/maps/blnevadamap.htm
Nevada Bureau of Mines and Geology: http://www.nbmg.unr.edu/

Viridian

Geology of Wyoming: Postcard Friendship Friday

Welcome to Postcard Friendship Friday, hosted by the lovely Marie at http://www.cpaphilblog.com/

"Geology - interpreting the past to provide for the future"

From the back of this postcard.
"This Geologic Map of Wyoming was reproduced from a part of Geological Highway map n. 5 (1972), Northern Rocky Mountain Region, published by the American Association of Petroleum Geologists, P.O. Box 979, Tulsa, Oklahoma 74101. For a free publications list or for information on geologic and topographic map coverage of Wyoming, contact the Wyoming State Geological Survey at 307-766-2286."

Oh boy, now we are getting into complex geology. And some fantastic scenery.

The big red blob in the northwest corner of the state is Yellowstone National Park, worthy of many postcards and blog posts. South of there is Jackson Hole.

The large oval-ish brown blobs (one is under the "W" in Wyoming) are large blocks of continental crust that have been thrust upwards by plate tectonics, often bending the flat-lying surface rocks above them. The dark green and other colored rocks in the northeast corner are the WY part of South Dakota's Black Hills. Devil's Tower is also nearby. Cheyenne, the capital of WY is in the south east corner and Interstate 80 meanders across southern Wyoming.

Wyoming has many natural resources, including oil (in the aformentioned bent rocks), natural gas, coal, and uranium. A shot from NASA, showing the mountain ranges topped with snow (and portions of other states):

viridian

PFF: Geology of Montana

Nothing too creepy from me, but see Postcard Friendship Friday for more from our hostess Marie and other people playing along. I'll skip the catacombs of Paris, thank you.

Today, the big wonderful state of Montana. Haven't been to the Big Sky country? Please go, for it's really beautiful. Yellowstone is in that inside corner. Glacier National Park is not to be missed.

The legend shows igneous rocks in red and pink. Very old rocks (over 1,000,000,000 years old) are in deep orange. Lighter orange is a formation called the Belt Supergroup. This is a very thick layer of different sedimentary rocks, some with pretty coarse (boulder-sized) stream sediments. Big mountains had been uplifted nearby and were eroding in a hurry.

The blues and greens are younger, Cretaceous or the time of the dinosaurs. There are some famous fossil localities in the general area of Great Falls.

Much later, bits and pieces of the Western USA came crashing into the North American continent. In a previous post I had described mountain building as a process similar to a carpet on a hardwood floor rumpling. Here, the push was so hard and so sustained, the rocks broke along faults and slivers were pushed up on top of other pieces. Think of how you can bend a piece of wood, but if you keep bending it, it will break. The faults are shown as thin black lines, esp. in northern Montana.

The other thing to note is the white line with hash marks along it. This is the extent of continental glaciation at the height of the last Ice Age, a pretty recent event in geologic time.

Ok, enough geology, I can see your eyes glazing over. Remember, there's a quiz next Friday! ;-)

Montana Bureau of Mines and Geology (MBMG)

USGS links for Montana

Glacier National Park

viridian

Postcard Friendship Friday - Postcard of Bedrock of Nebraska

Hello everyone to one of my favorite memes, hosted by our wonderful leader Marie, at Vintage Postcards.

Remember I am going through the USA from generally east to generally west, so hold on please for Montana and California.

We have the cut away block diagram and the legend or key on the right side, with youngest rocks (yellow orange) on top and older rocks (greens, then blues) on the bottom. Gee, just like the rock layers in Nebraska.

From the back:

"Block diagram of Nebraska Geology, on front, is available in The Groundwater Atlas of Nebraska from the Conservation and Survey Division, as is the Geological Bedrock Map of Nebraska and other maps and publications.

Nebraska Geological Survey

Conservation and Survey Division

113 Nebraska Hall

University of Nebraska-Lincoln

68588-0517"

Well! In the center of the continent there are many layers of flat-lying rocks. The bright pink at the bottom represents the old old basement rocks of the Precambrian. The thick gray layer is the Pierre (pronounced 'peer') Shale, named after the city in South Dakota, which after all is the state just north of Nebraska.

The state website is: http://www.nebraska.gov/dynamicindex.html.

The rolling plains of the American West is here, especially in the Sandhills region of north-central Nebraska. See these beautiful photos of this area. I have driven through here, and it is a beautiful place, empty of humans, but full of grass, sky, and wind.

And FYI: Willa Cather spent her formative years in Red Cloud, Nebraska.

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:

Illinois

Florida

Oklahoma

Alabama

Tennessee

Kentucky

New Jersey

New Hampshire

Massachusetts

Utah

Viridian

Bedrock Geology of Illinois

From the back:
Sedimentary rocks ranging in age from about 510 million (Cambrian) to 290 million (Pennsylvanian) are at the bedrock surface in Illinois and were deposited in and near ancient fluctuating seas. Cretaceous sands and gravels deposited in extreme southern and western Illinois are about 100 to 66 million years old. Tertiary rocks were deposited as coastal plain and deltaic sediments between 66 and 2 million years ago. Coal, oil and gas, building stone, fluorite, clays, groundwater and other resources in the bedrock contribute several billion dollars annually to the Illinois economy.

Illinois Geological Survey, 615 East Peabody Drive, Champaign, Illinois.
http://www.isgs.uiuc.edu/

In Europe, The time period correlating to the Mississippian and Pennsylvanian periods is known as the Carboniferous. It was a time of great swamps, both in physical extent and how long they lasted. Large amounts of plant material were deposited, which later changed to coal. Half of the USA’s electricity is generated from Coal-fired power plants, so this is still a major commodity. (It sells for $40 - $50 a short ton – don’t ask what a short ton is!) See more information (LOTS more) at the Energy Information Administration http://www.eia.doe.gov/fuelcoal.html.

Fluorite is a mineral with the chemical composition CaF2 – calcium fluoride. It is mined for the fluorine for industrial purposes.

We are in the heart of the continent – lots of flat-lying sedimentary rocks here.

PFF: Geology of Florida

A late hello for Postcard Friendship Friday.
Published by the Florida Geological Survey, Tallahassee, FL.

From the back of the card:

"The surface and shallow subsurface of Florida is composed entirely of sedimentary rocks - limestone, dolostone, sand, and sandy clay, deposited in and near a shallow marine environment. The thick section of carbonate rocks underlying the state has given rise to our many large springs and lakes. Florida produces 75% of the nation's phosphate and has large reserves of high-quality limestone, sand, peat, fuller's earth and heavy minerals."

Florida has much fresh groundwater and caves underground and beautiful lakes and springs, such as Weeki Wachee. However, pollution that gets underground can quickly contaminate the groundwater.

Phosphate is used as a fertilizer.

I was on the road last week, so a late entry today!

viridian

Geology Postcard: Oklahoma PFF

Happy Postcard Friendship Friday, with our lovely Hostess Marie.

Published by the Oklahoma Geological Survey, Univ. of Oklahoma, Norman OK

From the back of the card:

"The geology of Oklahoma was formed through millions of years when rocks that represent each geologic time period were deposited. Sedimentary rocks dominate exposures across the state, with major areas of igneous-rock outcrops located in the Arbuckle and Wichita Mountains of south-central and south western Oklahoma. The Oklahoma Geological Survey was formed in 1908 to investigate the geology, the energy-, mineral-, and water resources of the State and to make the results available to the public."

First of all, the 'mountains' of Oklahoma are really ranges of hills. The prairie are so flat though, they must have looked impressive.

The red colors on the map are old, uplifted igneous rocks. The tan and green colors are the various sedimentary rocks. The squiggles of yellow are recent river deposits - everything since about the Ice Ages is recent to a geologist!

The cross-sections at the bottom contain some important information. This is a view sideways through the crust and you can see the bending and folding of the layers. (How do they know this? Interpretation of seismic or earthquake studies.) The Anadarko and Arkhoma basins have produced a lot of petroleum, and continue to produce oil and lots of natural gas, which is Oklahoma's main petroleum product. An overview on how these resources formed is described on a Survey webpage. Oklahoma is not living in the past however. They are investigating wind energy too.

Viridian

Alabama Geology Postcard - PFF!

Happy Postcard Friendship Friday! With our lovely hostess Marie.


Today's card is published by the State of Alabama Geological Survey. "Compiled from Special Map 221 of the Geological Survey of Alabama."

Hmm. The printing on the legend is pretty small on this one, and I did not scan at a super high resolution. I'll tell you though that most of the rocks in Alabama are sedimentary rocks, made from rock particles laid down by wind or more likely water.

The oldest rocks are at the bottom of the legend, and the youngest are on top. The pattern in the upper right, of different rock layers trailing from southwest to northeast, is the absolute tail end of the Appalachian Mountains. Now, the Appalachian trail ends in Georgia. No mountains here in Alabama, just low hills. But they were folded like this because of collisions between 2 tectonic plates. Yep, long ago Africa crashed hard into North America (esp. at the latitude of North Carolina), and rocks were folded and uplifted as a result. Think of a carpet on a hardwood floor rumpling. Some folds are big, but they flatten out at some distance from the dog or child doing the rumpling.

Southern Alabama is made of younger sedimentary rocks, laid down when sea level was much higher than today. Pale yellow represents the most recent river and delta sediments. The prominent bay in the south is Mobile Bay.

Happy PFF, and happy geologizing!
Viridian