Geology Field Trip

[glenn kangiser]

I wasn't here most of yesterday because I joined the local Gem and Mineral Club.  Mostly because I wanted to get in tough with the local history and geology -- The Gold Rush 1849 and get the inside scoop on cool local stuff

PEG gave me permission to go but told me I had to do a report.

Randy Bolt is an Interpreter for the State of California Department of Parks and Recreation at the Mariposa Mining and Mineral Museum.  More important than that is that Randy lives his job and loves to share information with others.  He is a great asset to our club.

Randy volunteered to lead a group of interested members on a trip up Highway 140 into Yosemite and teach us some of the Geology and interesting information about the area.  Randy was previously a tour guide and teacher so you can't beat the quality of leadership he provided us.

First stop was along the highway above Bear Creek at a greenstone outcropping,  I only did a few small videos as I didn't want to use up all of my camera memory, but here is an example of the information presented to us Then I will add to the pictures as I get time.

In this area of pillow basalt and greenstone out croppings and road cuts, Randy explained the processes that have formed the Sierras.  Here is a picture of the fractured greenstone near Randy in which weathering shows the formation of the rock.



As we move on down toward the Merced River Canyon, rocks will switch to slate and phyllite.

[glenn kangiser]

We continued on up the canyon to a Geologic exhibit -- a natural one.



Along the way we could see the remains of old mining camps and bunkhouses.  Rich in many types of valuable minerals, many things were mined in the old days.  Randy explained that after the Yosemite Valley railway discontinued running up the canyon, it was no longer economically feasible to continue mining the lower value minerals such as limestone for the manufacture of cement.

http://www.yosemitevalleyrailroad.com/



All along the river you can see the remains of the old railroad bed as it made it's way from Merced to El Portal.

More info on the above picture.

Interesting Points along the Way
Woody - 67 miles from Merced. An immensely valuable deposit of lime rock will be utilized by the new cement plant of the Yosemite Portland Cement Plant, located at Merced.

This mile post was later named Emory after the manager of the Yosemite Portland Cement Company. Emory was his first name.
YPCCo. Hotels
The Yosemite Portland Cement Company Barracks above the Tracks.

Note that the other barracks recently burned down.

This is outside of the park and to many geologist , it is one of the most interesting features in the area.  It is a display of the oldest rocks in the area.

Erosion by the river water down to bedrock reveals a folded chert deposit which was once part of a deep sea bed.

[glenn kangiser]

Randy had prepared diagrams to hand out to us to explain the forming of the granites of the Sierra Nevada (and maybe to help part of it stick into my little pea brain).  

I have reproduced one here to show some of the information he presented us.  


Information courtesy of Randy bolt unless otherwise noted.  Drawing reproduced in MS Paint by me.

[glenn kangiser]

Is that enough to get me out of hot water for taking off? :-/

[glenn kangiser]

More info on plate motions.

http://pubs.usgs.gov/gip/dynamic/understanding.html

[PEG688]

Is that enough to get me out of hot water for taking off? :-/

It's a start  

Now is that a black H 53 in the windshield , upper left hand corner??



 

[glenn kangiser]

Guess I don't get out of it that easy, eh? :-?

H53 or possibly a big bug I was too lazy to totally clean off.   :-/

Does have a bit of similarity though.





There were several Helo's taking off from and around the valley yesterday.  I got a distant shot of a rescue chopper a couple miles away from Glacier Point with the new camera -- hand held about 50 to 1 zoom.

[glenn kangiser]

Back to the field trip.  We were told that the granite comes up in pulses and that El Capitan has 6 different pulses composing it.   Each pulse has its own specific make up like a fingerprint.  This picture shows magma inclusions in the granite.  As the granite comes up it melts its way through the overlying older deposits - metamorphic rocks.



El Capitan is a favorite for rock climbers the world over.  About 3000 feet up the face of the rock, with an additional 300 feet after you clear the top rim.



Later in the day we stopped and watched a few of them climbing the rock.  If you didn't know they were there you wouldn't even know it.  These are things a good guide can show you.

I got a shot of one using 50x zoom.  

[glenn kangiser]

Right above and behind us at this point ( Tunnel view) was where  Lafayette H. Bunnell arrived into Yosemite from the ridge route.  



We talked about the original inhabitants of the valley. It is commonly taught today that the Miwok and Maidu were the inhabitants, but  our member, Yosemite Indian brought up evidence that it was Piaute people who were the early inhabitants.  See more info in our indigenous housing section.  Reply #17

http://www.countryplans.com/cgi-bin/yabb2/YaBB.pl?num=1135060015/0

Below is a link to the first written contact between non-Indians and Chief Tenaya and his band. It was written by Lafayette H. Bunnell, the doctor of the Mariposa Battalion and the only person to meet and write about Chief Tenaya.

http://esnips.com/web/YosemiteIndiansWebResearch

This is not the only reference Paiutes have to prove what we have to say is true.  It's really a sad part of history that many people do not know.

Yosemite Indian has made this information available for download and reading off line.  Great history.

http://www.esnips.com/doc/e3059ddf-0ce6-4b3e-ba81-96095844851c/Lafayette-H.-Bunnell;-The-Discovery-of-the-Yosemite,-1851,-and-the-war-that-led-to-the-event

[glenn kangiser]

When you first see a lot of this it overwhelms you -- information overload --- TMI... TMI  but think about it a bit it begins to make sense.



The formation of hard and soft rings in this picture are the reason you will see pieces of this rock exfoliate in egg shell shaped pieces as it freezes or in other ways breaks. many times having sharp pointed pieces like spear heads but larger.

Randy spoke of them being formed by accretion.

[glenn kangiser]

As we headed up to Glacier Point, we stopped along the way to view the wild flowers and high country wet meadows in the Red Fir belt.  



Lodgepole pines were in the area nearby.  Red fir has shorter limbs and is better able to withstand the massive snowfalls that can occur here.  At the base of the trees is an area of Corn Lillys.  Note the base of the trees where there is no moss.  This indicates the average snow level.



Randy mentioned that this type of wetland is so sensitive that even building a trail across it alters the environment reducing or damming the flow of water and changing it's natural state.

[John Raabe]

Terrific slide show Glenn!  

Very interesting. Good job on the plate tectonics diagram. I think the San Juan plate up here in WA has some similar forces at work.

We didn't get the gold and Yosemite, however.  

[glenn kangiser]

The sketched out diagram by Randy goes into uplift of the coast range and the Sierra Nevada's.  After his explanations I now know why there are diatomaceous earth mines and fossilized limestone beds full of sea shells near the tops of various mountains on the coast range.  I never quite figured out how they got there.  If there is more interest in this I can sketch up more of the explanations of the tectonics.  The red pulses of granite forced their way up under the metamorphic rock above, then tilting, erosion and glaciation removed the covering from the granite domes and mountains we see today in Yosemite.

Bridalveil Fall was flowing quite well as we could see from the tunnel view, but this is a short year for water.  Very little snow left.

[glenn kangiser]

Here is a picture toward Little Yosemite Valley, Vernal Falls and Nevada Falls.



With my little gorilla Pod and 50x digital zoom on my new camera I was able to get a picture of the bridge over Nevada Falls - the one on the right (I hope).  Both were taken from the same location by the railing at Glacier Point several miles away from the fall.

[glenn kangiser]

I guess we have the same Pacific plate working on all of our volcanic areas.  The Pacific Ring of Fire.



More here.

http://vulcan.wr.usgs.gov/Glossary/PlateTectonics/description_plate_tectonics.html

[PEG688]

Nice photos Glenn , Ring of fire   did I ever tell you about the day I ate that whole jar of hot peppers   now that was a ring of FIRE

[glenn kangiser]

Wasn't it the day after? :-?

You are supposed to eat a bowl of ice cream afterward  so you can say "Come on, Ice cream"  after the big event. :-/

A few more pix to go but gotta work early tomorrow.

[glenn kangiser]

Here is Yosemite Valley near the time when the white man first discovered it.  Remember that the indians took care of the valley setting fires every few years to keep it clear of brush and the major vegetation and treees you see nowadays.  The oaks didn't burn with the grass fires and were kept healty so they produced good acorns.

 
This was more from like what Bunnell would have seen.

We continued on our way to our ultimate destination,  Sentinel Dome.  A nice fairly accessible dome of granite overlooking the park and the nearby world.

[John Raabe]

The native American use of fire is something we are only starting to understand from an ecological perspective. It has powerfully shaped the world we called "natural". That world appears to have been much more actively managed than the romantic european (and later American) vision of America as a wilderness "touched only by the hand of God".

[fourx]

The formation of the present landscape by fire mangement theory, while a nice concept, is far more likely to be the result, there as here, I think,  of the use of fire as a means of producing the maximim number of kills per hunt for the minimum amount of effort ( a Google for a book called The Future Eaters by aussie scientist Tim Flannery details this and also the extiotion of mega-fauna here, such as marsupial lions, by the same means).
In much the same technique as running a herd of bison over a cliff- and a bunch of kangaroos, here- a fire would be lit on one side of a group of trees with the wind behind it- and the rest of the tribe would be waiting on the opposite side with spears and clubs...of course, there was no way of putting the fire out, and the tribe just moved to another area of tribal lands and did the same. Each tribe moved roughly in a circle once per year, with tribes in this area moving to the coast in the cooler months where they feasted on oysters and fish, to the 3000 foot tablelands where they ate bogong moths and the usual possums and kangaroos- and burning on the way. This is the reason that gums are so widespread here- they are the only tree that can withstand repeted burning. The areas which were too damp for them to burn, such as the rainforest in the creek at the back of my house, with palms, treeferns, ceders and giant creepers show just how incredibly beautiful the country once must have been

[glenn kangiser]

Interesting concept, Pete.  Not the story we get today but a distinct possibility.  We do know that they used the pulp,juice of certain plants to take the oxygen from the water so the fish would float to the top to be gathered.

[glenn kangiser]

The local Indians tell of fires to keep the brush down , fertilize the earth - ash has lots of elements necessary for growth, and increase the Acorn harvest, John.

Randy mentioned theat the "Foresta" (town name) fire in 1991 gave us an example of what happened after fire.  It produces an area in a few years that promotes the type of plants deer and wildlife like.




Older clean brush free areas in Yosemite.  (Photo or drawing?)



Currently ---an area of the Foresta fire.

[fourx]

"". We do know that they used the pulp,juice of certain plants to take the oxygen from the water so the fish would float to the top to be gathered. ""...
....just as the Western print and electronic media do today at the bidding of their masters. The workers float, gasping, on the surface of an endless treadmill of mortguage payments, car payments, kids education payments, in your case health payments, sedated by an excess of beer and sport. Same old, same old....pardon me for being a sour cynic.
It's not a theory- it's fact- Aborigines do just the same in central Australia today- but they use rifles rather than spears. The romantic concept of the noble savage, in tune with and taking care of his enviroment, has about the same credibility as that bullshit 1970's quote about treading on the Earth lightly, which was written by a white advertising copywrighter, and about the same relevence today as a lava lamp.

[glenn kangiser]

An environmentalist friend has used that same quote on me - with my Bobcat.

Massive pollution - radiation etc., is one thing -- it takes a giant corporation and government getting it's cut to make the worst of it.  Scarring of the land many times heals over to where in a half century or so it is hard to tell anything was ever there.  The ugliest scars on the face of the earth now are the big cities -- and they are not healing well. :-/

[glenn-k]

Never got the rest of the pictures posted here yet. :-/

The short hike up Sentinel Dome had lots of nice views -- trees, exfoliating granite - and the sun near setting over the horizon.





A great view of Half Dome.



There goes the sun.