More Schist and More

I know it's enough already with the schist, but it's not as simple as I thought to identify.

Schist: "A coarse-grained metamorphic rock that consists of layers of minerals and can be split into think irregular plates - from Greek 'skhistos' - to split"



Gneiss: " A metamorphic rock with a banded or foliated structure, typically coarse-grained and consisting mainly of feldspar, quartz and mica - from Old High German 'gneisto'- to spark"



Okay, these are the same rocks it seems to me, I get confused most of the time. The minerals in schist are also mainly mica, quartz and feldspar. Plus maybe some graphite, hornblende, talc and chlorite.

But here's some good news:

"Gneiss resembles schist, except that the minerals are arranged into bands. Sometimes it is difficult to tell the difference between gneiss and a schist because some gneiss appears to have more mica than it really does. This is especially true with mica-rich parting planes."

Most of Manhattan has a bedrock of schist and the Bronx has gneiss.

A glacial erratic is a chunk of rock that is not native to the environment in which it finds itself. It was dragged and dumped there by when the glacier retreated. Erratics can be found hundreds of miles from their home. Poor things. Or maybe they wanted to get away anyway.

When Central Park was constructed in the late 19th century, many of erratics were removed (hopefully shipped back home), but some remain. This one was obvious, but I'll have to find more.

Overwhelmed

Acadian granite, gneiss from Delaware, Grand Canyon sandstone/shale cliffs and slopes, intrusive basalt into Acadian granite, angular unconformities at Siccar Point, Scotland...

BUT!

I identified schist and gneiss and marble in my rock collection!!!! I'm so excited!!!! I wish I could measure the mass and weight of these rocks; the schist and gneiss seems so light. Not like granite. But I guess when compacted into enormous bedrock, they can support sky scrapers. I think schist is the main rock foundation of Manhattan. And where the skyscrapers are built depends on how deep down the schist is. If it's too deep, not tall buildings. I know this is common sense, but I didn't realize that depth varied so much up and down Manhattan.


And I was identifying marble as quartz and it is definitely not - I hope. The crystal structures are different. I have a loop to magnify my vision. I wish I had a microscope.








This is mica:










I don't know what this is, but I find it in Central Park:

SANDSTONE!!!!!!

Sandstone is a sedimentary rock made up of the minerals quartz and/or feldspar. The clear quartz and amber feldspar create a brown, yellow, or red color But not in this specimen which was glued on the board at the beginning of the neglected "Geology Walk" in the NYBG forest. That hurts my head.

Besides being called a Sedimentary rock it is also called a Clastic rock. This means that the sedimentary materials are made up of older broken up pieces of rock.

They are formed by layers of sand and mineral deposits (under water or on land) covered by other sedimentary layers or rocks. The pressure from this forces causes them to compact and cement. Silica and calcium carbonate are usually the binding agents. I don't know where they came from. This also hurts my head.


Antelope Canyon, Navajo Reservation, Arizona

I was surprised to read that some sandstones are not as susceptible to erosion as their sedimentary brothers and sisters. This is because of the hardness of the individual grains and the uniformity in their size. Yet, somehow, it is easy to work with to make buildings and other structures. As I'm sure everyone knows it is highly friable. Such a word and it only means "easily crumbled". Apparently this makes it an ideal material for a grindstone or knife sharpener.


Hawa Mahal, Rajasthan, India

I am going to assume that different varieties of sandstone are a result of different feldspar/quartz ratios, amount of pressure, heat variations and the atmosphere in which they were made and have emerged.

So, to recap, it's easily broken and made up of broken pieces of older rock, yet slow to erode and hard enough to sharpen a knife and grind stuff.

Very moody rock.

The sandstone layers in the Grand Canyon, being more resistant, form the cliffs while the shales and siltstones, easily giving way to weathering and the scouring from the Colorado River, form as slopes.

I am the Fox in the Rox

Why does one person have to get all the credit for discovering, creating or developing something when there were others on the scene as well? Someone gets the most funding, writes the flashiest book, has the most connections, and the most ambition and, well, there you are. Even if this person him/her self acknowledges these other remarkable people, only 1 person gets that award. And everyone else vanishes like snow on the sea.

Of course, I am bitter and devastated by my failure to be anything close to the best at anything, despite trying. IX told me the story in Aesop's Fables about the fox and calling the grapes sour just because he couldn't reach high enough to get them. I'm more like the fox than someone making social commentary.

There are people with extraordinary brilliance, drive, knowledge and courage, after all, who have left bodies of work that prove their worth; paintings, music, sculpture, novels, poems et al. Aren't they fully deserving of credit and everlasting celebrity? They may have had more advantages and luck, but does that matter?



Actually, I'm much more pathetic than the fox. I was foolish to think I could get the grapes, too, but if they had suddenly grown heavy and dropped down on me and I ate one, I'd see the fox looking at me saying "See! I told you!"

You may be wondering what all of this has to do with geology. Well, it's about the Colorado and Green Rivers and Grand Canyon and who exactly discovered what. It's murky when it comes to exploration.



One of my favorite geological terms is "The Great Unconformity". This refers to a layer of the Grand Canyon near its base that has eroded away leaving no trace. Radiometric age dating shows that the gap of time between the 2 layers is over 1 billion years. Other sites in the world have only "unconformities" or "angular unconformities", but not GREAT unconformities!



These pictures show the location of the G.U. at close range. Too close I think to get any kind of perspective. Back to flickr...



Does that help?


The Gates of Lodore on the Green River in Colorado

This entry was supposed to be about the 1869 Powell Expedition down the entire length of the Colorado and Green Rivers which included portions that had never been explored and were unchartered. But there isn't a whole hell of a lot to say about it except what's in the previous sentence unless I want to go into all kinds of tedious historical detail. But there is a link with all my musings about notoriety here, though. Powell took more credit for the expedition and geological discoveries than was his due. Apparently, he didn't even include the names of his team in his memoirs and books. He was undoubtedly a great leader, but maybe egomaniacal. Oh, and he gets even MORE credit because he had only one arm. He lost it in the Civil War. Who can beat that combination? But maybe he really WAS such an amazing hero for mapping and navigating the Colorado River etc. What the hell do I know. I am just the sour fox. The terrible picture is the Powell camp where they first embarked.


Did you know that the blue Colorado River you see today is not at all what the river looked like at the time? Damn dam lakes have absorbed all the silt that the river carried to the Gulf of California and also used to further abrade and erode the rocks it cut through. It was muddy and yellow. That's how it got its name. (I get the 'color' part but I guess the r of the 'dor' eroded. But without the dams and their gleaming lakes, we could never enjoy these new vistas...









Well, I think that says it all.

The Rocks Don't Hurt

Here's my attempt to understand the geological world. Couldn't understand myself, couldn't understand people or music, but maybe I can understand rocks. They are noble and patient and complex and wise and enduring. They fall apart. Then they reinvent themselves. Adapt and transform. Maybe not one atom in rock ever leaves earth. And most importantly, rocks don't hurt.

Metaphors and imagery aside, can rocks and landforms really be 'understood'? Well, no, not even to experts. They extrapolate etc. We don't know exactly what happened to form the Rocky Mountains just as we don't know exactly what happened during any historical event. I guess a humbler and more realistic goal would be to collect knowledge and make the best sense of things in my little brain and understand that I can never really understand. So it ends up like myself, people, music etc.


Except, most importantly, the rocks don't hurt. I'm not trying to be poetic or use this as symbolism. I'm just stating that the rocks don't hurt (me) or anyone else. Unless a boulder falls on you during a landslide or you step on a sharp pebble while walking on the beach. Or someone just throws a rock at your head.


In the past 24 hours, I have a thin grasp on Epeirogenic Uplift - uplift that doesn't build mountains but lifts a large slab of land, like the Colorado Plateau and, apparently, the Appalachian Plateau (I need to go the Smokey or Blue Ridge Mountains to get back to my world in the East. I guess everything in the West has is more flashy and exciting and dangerous; the mountains, canyons, deserts, rivers, the Buffalo hunting Native Americans sweeping across the plains, the ancient remains and artifacts of ancient civilizations, the cactus, the silver mines, Las Vegas...)


Photos in 2 different locations of glacially deposited boulders in North Eastern New Jersey.

I am longing to understand this "fold and thrust-belt" concept. It's something that happens as a result of volcanic mountain building. Oh, I have an equally slim grasp on how subduction of one tectonic plate beneath another causes magma in the mantle to blast through the continental crust. And what causes a fault and what are some of the results of earthquakes resulting from their activity? And what is this "foreland" concept?

And then there are the glaciers. If I can find the right books, I might understand better how they affected the landscape. But everyone interesting wants to write about the wild west.

I did learn that the Appalachian Mountains were formed from colliding tectonic plates from the east. The African/Europeans plates collided with North America and all the processes were set in motion to build an enormous mountain range like the Himalaya. So, this was not subduction, but collision. I hope.

Now, I should put some pictures in here. How the hell do I illustrate what I've written? West, East, my rock collection. How do I take pictures of my rocks?

Did I write my wish list of places I want to visit (within my travel budget realms of reality). The order is of no significance.

Shenandoah National Park
We can stay at a cabin or lodge which I assume is the equivalent of what we stayed in in Grand Canyon for about $150/night. We fly into DC very cheaply ($150-ish), we get Wayne's enterprise deal, drive one hour to the park. And IX mentioned we could try to spend a day in DC at the Smithsonian. If we have more time, we can maybe visit some civil war sites. Ambitious.

Acadia Park

We always want to avoid crowds so we never go to the Bar Harbor peninsula. But it's high time to go to the park. I've got the geology book and everything. The usual travel to Bangor, hopefully the car deal - unless site59 is cheaper - and easy enough to find a reasonable place to stay. Another trip that doesn't require IX to take too much time off work.






The Pine Barrens

It seems like a very unusual and fascinating place from what I've read (especially inn the McPhee book!), but the Wharton State Park is only 2 hours away.






Canyonlands/Bryce/Zion/Yellowstone/Sequoia Parks

Obviously.





And I want to research those crystal quarrying parks that are on that show Cash something or other. In New Jersey at the Sterling Mines you're supposed to be able to go in and use a pic and chip out fluorescent rocks. Of course you can only see them with fluorescent light...



Catskills

For an over night, I guess. They seem pretty trampled on and old and dilapidated and like they've seen better days, but I think there are some very pretty trails and I'm supposed to be able to find fossils with my pick.


Adirondacks National Park

Also an easy trip. Fly to Vermont, car and reasonable lodging.

I wish I could get up earlier to get to the day hikes in NJ and NY - want to check out that nice Orange County area but I don't want to stay overnight.