Geology

“I learned something that struck me as quite interesting in my Geology class earlier this evening.

Did you know that all that Granite Sheeting on domes is caused not only by frost wedging but by a process called Unloading. What that means, is that when rock that formed in a high pressure environment is exposed at the surface, the low pressure allows the rock to expand and crack causeing onion-like layers to form Exfoliation Domes of exposed Granite. You can see this on about any large areas of exposed granite.

I just thought this was cool and wanted to share it with yall. I always thought that it was all due to heating and cooling, water and ice.

^^^ThinAir^^^”

“Limbert Dome, and Half Dome are good examples of this.”

“Metorology mo better”

“Geeze DM99, maybe you should look into English studies a little harder. Typo or not but if that is your major aleast take the time to spell it correctly. Sorry if I sound pissy but......


Geology was the second most interesting course of studies I took back in college. It really helped me to understand the earth, forced me to have a greater apprecation of the land that may of us just walk over and never wonder why this or that happened. You will never look at a set of mountians or a river valley the same way.

If you have the opprotuninty look into taking a anthropology/archaeology courses or two.”

“rocks rock!”

“Briar, maybe you will take the opprotunity to check your own postings!”

“Anhtro is the major for inquiring minds. Because is covers so much, it lead me to a whole string of BAs, BSs and an MS. Geology is but one.”

“Opprotunity was not my major FLY. I miss spell words frequently, but ones major come on. Hey but thanks for pointing that out and so now I stand corrected, sorry DM99 for ragging on you. Just thinking I was the only wise a$$ around here. I guess I stand corrected on that matter as well, thanks FLY.”

“I did know that, and when I learned it my reaction was about the same as yours, ThinAir.

You might be interested in the book I'm reading now: Exploring the Highest Sierra, by James G. Moore. It has a couple of chapters on the history of Sierra exploration and mapping, and then the rest of it covers geology. Lots of great illustrations.”

“I took Geology as my science sequence in college. Man... what a science!

Any granite that you see has one helluva story - if only rocks could talk. Granite is a maffic (sp?) rock that cools very slowly, very deep below the surface. The Black Hills, Tetons, et al, are granite. Dog! Could you even begin to imagine the forces that brought them to the surface?!

Speaking of the Himilayas...
India was once an island. It drifted across the Indian Ocean - via plate tectonics - and RAMMED into Asia... creating the Himilayan Range. That's the same fashion in which the Appalacians were formed - long, long before the Himalayas. Everest is 29,000 ft. high. Some mountains in the Appalachians were close to 40,000 ft.
As is evidenced by the recent earthquake, India is still trying to move inland.

Speaking of plate tectonics.
The Pacific plate is slowly moving over several "hot spots" that are actively spewing magma. One can determine the direction of movement simply by the alignment of the Hawaian Islands - which is slipping across a hot spot and continuing to form as we read and write.

Much of California was once an island, too. It drifted NE toward the N. American plate until making contact. It still wants to move NE'ward, but the continent won't permit it to do so. Instead, it is creeping northward along what we call the San Andreas Fault. Someday L.A. and San Fran will be on the same latitude! Kewl! All the while, the Pacific plate is being subducted below the N. American plate (and California). The subduction is causing the heavy Pacific plate to plunge into magma below N. American plate, which melts the seafloor - forming more magma. This magma is being forced to seep toward the surface. It has escaped to form the volcanoes along the Sierra Nevadas, ie, St. Helens, Ranier, etc. I think it's interesting to find both volcanic and upheaval mountains in the same ranges.

The Appalacians are sedimentary rock. They were once a sea floor that were upheaved when the North American plate and Atlantic plate collided. I bet that was noisy. The continental shelf is comprised mostly from Appalacian sediment.

Oh man -
speaking of river dynamics...”

“gojo, if you do that all the way to cumberland island, sara and i will throw your ass out of the boat! LOL!!!!”

“ooops, that's meteorology. Stuipid e button.”

“Ummmm...Granite is a "felsic" plutonic igneous rock!

The High Peaks region of the Adirondacks also ehxibits exfoliation spawling like what Mr. Air mentions. These exfoliation planes of weakness are what gives rise to the occurrance of slides throughout the region.”

“I was gonna let gojo off the hook for that, but Buddur's right. Basicly felsic rocks are lighter colored and Mafic rocks are darker Basaltic material. Like Devils Postpile”

“Yes, those damb liberals and their imoral earthquakes”

“Yeah what yaw said!!”

“oops,
"plutonic"

Speaking of Cumby...”

“Growing up in southwestern Michigan, geology was pretty abstract beyond dune formation. Then I moved to the Upper Peninsula and learned the term Canadian Shield. Suddenly I was in Rock Country. Mines, rock hound clubs, weird magnetic fields, basaltic "black rock" coastlines, red sandstone buildings, agate beaches. A major addition to the outdoor and cultural experience.”

“hey, you can tell me all you want about cumby. it's got an interesting past.”

“On a scale from 1-10 (D'oh...it's Moh) limestone (rock) has a relative hardness of 3, glass 5, and quartz (mineral) 7. Glass is harder and can scratch limestone and quartz can scratch glass, etc, although limestone cannot scratch the glass because it is relatively softer. However, if ya throw tha limestone hard enough at tha glass...

What's the difference between a rock and a stone?...A rock becomes a stone after it's thrown through a glass window!”

“Here are some interesting pics for you geology/paleo buffs...

Dino footprints

More dino prints
Stone Ripples”

“Geologists have rocks in their head.”

“...and minerals!”

“there is nothing like a nice sun warmed slab of granite to stretch out on .....
I love rocks
and the Stones too”

“I've found the backpacking experience is enhanced greatly by knowledge of the geology one hikes through.

The current Appalacian chain is the fifth mountain chain formed in that area (all previous ones having subsided prior to having been thrust up once again by tectonic movement), and as pointed out above once had higher elevations than the current Rockies.

The oldest exposed rock in the general area is found on Mt. Wilson, north of Ashville. It's 1.8 billion years old. Great area in which to hike.”

“SW NC has some awesome mineral collecting localities!”

“Reunite Pangeia!!!”

“Bad spellers of the world untie!!!”

“2nd greatest book in the world...the rock record!”

“Ok, you want to get serious?
What's the difference between Pangeia (SP?) and Gondwanaland?”

“If I'm not mistaken Pangaea was once the super continent that broke into two pieces one being Gondwana and the other was called Luarasia I think.”

“Good one Mr. Rabbit! Gondwana being in the southern hemisphere, and Laurasia in the northern.

Any other Qs?”

“How 'bout...What evidence is there that these continents were once joined together as one?”

“Magnetic polarity of rocks..... the composition of rocks..... fossilized(carbon imprints) biological remains of plants and animals..... radiometric dating and studing of cross sections (intrusion of newer rock thru an older rock) and the superpositons(newer layers on top of old) of layers of rock.”

“Does ontogeny really recapitulate phylogeny?”

“Here's another Q:

What state was the sight of our nation's first gold rush?

Clue: it was when the phrase "There's gold in them thar hills!" was coined.

Clue II: This state's capitol has a thin layer of native gold covering it's dome.”

“Colorada”

“Next gold rush question:

Where was gold first discovered in California?”

“And when?”

“the hills of dahlonega!”

“Bill Clinton ROCKS!”

“I think Georgia (maybe Dahlonega 1828?) had the first gold rush. I've found old gold prospecting sites south towards Lincolnton, GA. Also around the same time gold was found in SC north of Abbeville. And there there was a placer gold mining town near Salem, SC around that time.”

“First gold discovery in California is actually unknown.

Both the Cahuilla and Agua Caliente tribes were making gold jewelry when initially encountered by De Anza.

De Anza 'discovered' gold in what is now Anza-Borrego Desert State Park.

So those original uses predate the Placerita strike by unknown centuries.”

“Good point, Gordon. The first documented strike was 1842 in Placerita Canyon, and that's what I was shooting for--but the locals were obviously using gold from somewhere long before that.”

“I understand that both tribes hit it big again when................

The California Indian Gaming Act passed.”

“Neil Young rocks too!”

“keep on rockin' in the free world!”