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Carpal Tunnel
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Carpal Tunnel
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Crystal's cleavage isn't important to geologists?
Well, maybe it is, maybe it isn't but I doubt if it is an important component that assists geologists establish the structural history of the area.
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Carpal Tunnel
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Carpal Tunnel
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interstesting stales-- i have heard these odd boulders called glacial erratics .
there are some famous ones locally ..On Long island, Shelter Rock, give its name to a town and road.. in the bronx, in the Bronx zoo "the rocking stone" and other rocking stone in westerchester county. Faldage, do you kniow of any? I can't think that there would be three i know.. and none up your way..
both of the rocking stones are huge-- the bronx one is a over 2 meters on each side, (it it more a less a cube..) and it sits on an outcropping of gniess.. and if touch, and pushed at just the right point, it will move an inch or two, fall back, and rock back and forth a few times..
its well know.. and when the zoo expanded, special care was taken not to disturb it. it sits just outside the World of Darkness building.. the second one, is harder to rock.. and is less than a mile from the Cross county shopping center.. everytime some one wants to develop the land its sits on, local geologists, native americans and general NIMBY's get up in arms and demand it be preserved.. so far, they have won.
glacial erratics in souther michigan pointed explorers to look for copper in norther MI, many of them had copper.. some geologist think that there are richer copper deposits in canada, and that the copper bearing rocks are from further north still..
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Carpal Tunnel
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OP
Carpal Tunnel
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"Crystal's cleavage isn't important to geologists?" Show us a picture of Crystal!
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old hand
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old hand
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Bingley - I'm afraid Dr Ridley's reply was lost in the hubbub I caused. His smirk said it all though!
stales
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old hand
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old hand
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ww...
We're not just splitting hairs here (hehehehe)
The cleavage of a particular crystal or a type of mineral is critically important to a gemmologist - as opposed to a geologist. This property, along with lustre/er, streak, hardness, transparency etc is what contributes to whether a mineral makes a good gem - or how it should be used as a gem - ie should it be faceted or cabochoned frinstance. (A soft mineral or one that fractures easily will not last long if used in jewellery).
The cleavage of a rock unit however, when looked at in conjunction with its jointing, folding and/or faulting, enables a structural geologist to work out the stress and strain regime required to bring about the deformation. This assists them in working out the the geologicAL history of the district. This enables them to write learned papers, the volume of which is directly proportional to their future scholarship and departmental funding - as well as the likelihood of them attaining a professorial appointment. Occassionally their findings receive application in the real world however, when "proper" geologists - ie exploration geologists - use the information to explain why an economic mineral deposit was found where it was. It's important to note that the learned papers are always written AFTER the deposit has been found - they are NEVER instrumental in the ore body being found. (BTW - this is my first 'white bit' - how'd I go?
Naturally enough, these macro-scale events are usually seen at the micro-scale - ie the rocks' constituent grains are also deformed. Too much deformation would negate their value as a gem.
Now, did I get enough four syllable words in? Very important part of geo-speak those four syllable words. "Phreatomagmatic" is a beauty - it's got six!! Got the taste for white bits now!!
stales
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Carpal Tunnel
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Carpal Tunnel
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Fascinating reading, Stales, and your white's all white!!
We have some huge boulders out here in Dinwiddie County, Virginia, that my Uncle LL says were left by the the glaciers. It's a fantasy of mine to go traipsing about the countryside with a geologist to get the big view of how things rocky settled down here.
By the way, a geologist, a Dr. Walz from VCU, visited our school last year. He had lots of big rock samples. I talked to him briefly before his demonstration for our fourth graders about his samples. I asked which was the oldest in his collection as I eyed some whoppers that looked really hard and old. I was surprised when he lifted a big chunk of slate and said, "This one is four billion years old." I was surprised because the slate looked, I dunno, least old--something more frangible than the others. If I had two more lifetimes to live the first would be to study dendrology; the second would be to study geology. You're in a great field.
Best regards,
WW
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old hand
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old hand
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dubya squared Show me a kid that's not fascinated by rocks..... I think something happens during the teen years where more pragmatic likes take over. I used to sell mineral specimens - many of which went into small, sweaty, sticky hands in exchange for the 50 cent piece their parents had given them to spend at the show. For interest's sake, the oldest rocks in the world have been found at the "Jack Hills" in the Kimberley District of far northern Western Australia. (So I am not the only fossil in WA!) The tiny zircon crystals were identified and dated by a guy I went to university with - Peter Kinny - aka Skinny Pete. Dated at 4.4 billion years, it is more technically correct to refer to "the oldest rock grains". This is because the rock they were found in is a metamorphosed sediment - and therefore the original rock that contained the zircons has been weathered away, releasing them. What I'm trying to say is that the zircon grains actually predate the rock they are now in - but it still stands that these are the oldest rock units on the planet. The following URL provides an easy to understand collation of old rocks. Its logo is the actual zircon grain ID'd by Skinny Pete and the crew at Curtin University, Perth. There's also a few photos of the Jack Hills area - some pretty tough country. I wonder if this was where Dr Walz got his specimen? (ie did he go Walzing Matilda through the Aussie outback?) http://www.geology.wisc.edu/zircon/Earliest Piece/Earliest.htmlBTW - I got out of geology a few years ago - luckily. There's been wholesale unemployment since the Bre-X fiasco in 1997 and subsequent crash of commodity prices. Something like 1800 geologists now underemployed in Perth alone. Can't say I saw it coming - I just wanted to spend more time at home. stales
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Carpal Tunnel
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Carpal Tunnel
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I enjoyed reading your link, wwh. The part about the crocodiles was most interesting: KILLER CROCS. In the jungles of South America, Golden Star Resources Ltd. has faced even more formidable obstacles. The Denver-based company, founded in 1984, is now one of the world's largest specialized exploration companies. Jaguars, wild hogs, and killer crocodiles lurk near the company's properties. Plate-size spiders eat birds, and malaria is a constant threat. Dealing with the locals can also prove challenging. When Golden Star CEO David A. Fennell met with tribal chiefs near one camp, ''they had a prayer to the gods that our geologists would have the eyes to see the gold,'' he recalls. He and his wife also went through a tribal wedding ceremony.and: Coming so soon after Bre-X, that may seem like dangerous advice. But gold rushes have always been fueled by people willing to take extraordinary risks. Few are likely to wade through the jungles of the Amazon, or venture to the mountains of Central Asia, unless they're possessed by intoxicating dreams combining greed, glory, and gold. It's a mix that can easily spin out of control. But at least for now, the potential rewards seem too great for prospectors with the deepest pockets and the steeliest nerves to pass up.http://www.businessweek.com/1997/20/b352798.htm(Your link again) "Greed, glory, and gold," not to mention green crocodiles lying in gluttonous wait...the ultimate lurkers. Best regards, WW
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old hand
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old hand
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Two weeks ago I received an email from a geologist with the USGS, in part it read..."...if you can prove altitude clustering is non-stratigraphic, trying to keep the story in the second half of thr pleistocene opens a big can of worms, because the implications for subaerial fluvial geomorphology are fairly sweeping. ( Oh Baby, talk dirt to me, USGS; Say " subaerial fluvial geomorphology" for the nice man, Junior.) the sentence above in blue, as well as the rest the email was, to me, clear, precise, and written with great economy. Geology, unlike other disciplines such as the "dark art of lawyering", has taken care in developing concise referents for the words in it's lexicon. To some extent if you know the words you pretty well know the science.
But Geology's careful love affair with words is not surprising, three-thirds of the geologists of the world spent two-thirds of the last century naming things and looking for oil, while every schoolboy who had ever worked a picture puzzle could see that South America fit snugly with Africa. But even after "Plate Tectonics" I think it best not to reinforce too many neural links to the words "plumes", "hot spots", or even "plates". It may be years before Geologists know precisely what they mean.
Sometimes though, Geology ignores important questions that interests me. For example the " Carolina Bays." While they are neither restricted only to the Carolinas nor are they bays, the origin of 500,000 elliptical northwest trending lakes is largely ignored by geologists and so left to free thinkers to explain. I am personally torn between the "Mammoth Wallow Hole" theory and the "Exploding Comet".
One odd theory (Thom 1970) combines...wind deflation with perched water tables and shore erosion at a ninty degree angle to the prevailing wind. Maybe Wordwind, AWAD's own prevailing wind from the Carolinas has an opinion or knows the answer.
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