#18178
02/03/2001 3:21 AM
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Carpal Tunnel
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Carpal Tunnel
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Tonight in BBC News Sci-Tech there was a word new to me, about danger threatening areas near West Coast volcanos. Mudslides caused the most extensive damage to property from Mt.Saint Helens eruption. Their technical name it turns out is "lahar" which I had never seen before. Perhaps it would be interesting to have contributions for other uncommon words on this subject that may show up in news. wwh
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#18179
02/03/2001 4:14 AM
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Posts: 11,613
Carpal Tunnel
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Scree is pretty uncommon. Shoot, there's a name for the particulate that falls during and after an eruption, and I
can't think of it. Max would know.
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#18180
02/03/2001 4:27 AM
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Carpal Tunnel
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Shoot, there's a name for the particulate that falls during and after an eruption, and I can't think of it. Max would know.
hot stuff
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#18181
02/03/2001 10:27 AM
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Posts: 3,146
Carpal Tunnel
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A lahar occurs when a lake in the crater of an active volcano overflows or the mountain erupts. They're a mixture of water, ice and volcanic debris. Lahars are pretty diabolical, because they generally happen when no one's particularly looking for them (being at the tops of mountains an' all). One occurred on Mt Ruapehu in 1953, swept down the mountain and destroyed the main trunk railway bridge at Tangiwai between Waiouru and Ohakune a few minutes before the daily express between Wellington and Auckland crossed it. A lot of people died. There's now a lahar warning system on Mt Ruapehu. If you're interested, this link will show you what's what! http://www.learnz.org.nz/2k/tongariro/t_lahars.htmScree is common enough here, Jackie. It occurs on the majority of the mountains in the Southern Alps which are mostly made up of greywacke rock. Scree is loose rock and gravel in a continuous slow landslide. Crossing it carelessly is one of the most common causes of injuries to hikers here in NZ. I got caught in a scree slide some years ago which was set off by the guy I was hiking with. It carried me about 20 metres and then "ran out" on a shallower slope below. But there could just as easily have been a bluff below me and then it would have been "good night all!" For some strange reason I wasn't very polite to him in spite of the fact it was just an inadvertent misstep on his part.
The idiot also known as Capfka ...
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#18182
02/03/2001 1:00 PM
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Posts: 11,613
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I think the word I was looking for was tephra. It was in C.K.'s link--thank you. I sicced Atomica on it. Atomica
didn't have it, and switched over and google-searched on its own! Thanks again, Jazz-o.
And, oh, C.K.--I meant that the word scree is not in common usage. I am very glad you're still with us.
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#18183
02/05/2001 2:15 AM
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Lahar is one of the contributions of Javanese to the English language. Others are batik and gong.
Bingley
Bingley
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#18184
02/05/2001 9:28 PM
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Carpal Tunnel
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>Shoot, there's a name for the particulate that falls during and after an eruption, and I can't think of it. Max would know.
>hot stuff
This IS a family chat area. Please refer to Jackie by more acceptable terms :)
TEd
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#18185
02/05/2001 11:44 PM
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Carpal Tunnel
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Carpal Tunnel
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hot stuff... Thanks, Ted. The gutter hath a new king! 
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#18186
02/06/2001 11:22 AM
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Posts: 393
enthusiast
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enthusiast
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Volcanoes give us aa and pahoehoe, not to mention tufa and tuff, and pyroclastic flow.
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#18187
02/06/2001 1:10 PM
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Jackie, i think scree is pretty common up and down Appalalain's-- and i know it also exist in Rockies-- same sort of factured shale-- most of the scree i've seen has been slag heaps (I paid good money to take a tour of a coal mine, and afterwards when fosile hunting-- they took us to a slag heap of shale, and let us climb up, and slip down the scree while hunting-- but i got some good fosiles!)
We also got to see a great example of a syncline and anticline-- geologist are fun--
Their names for things show even they have trouble remembering what's what.
Like:
Syncline's point down-- to the place sinners might end up--
Anticlines go up
These words are used to define the corregated like folds in rocks-- They are commonly seen in mountainous areas, and US east coast (very old, very eroded mountain range) has some great examples. In new mountain ranges they are often not as visible.
and
stalactites (stay up on the roof of a cave---glued on tight!) and stalacmites.
One of NY geologist-- Sydney Horstein-- has a little ditty about NY geology
Manhattan is schist
The Bronx is gneiss,
and NY is not with out its faults!
(it is common to intentionally mispronounce schist)
It not much-- but we've had 2 earthquakes in the past 2 months-- both in the 2's (2.5 and 2.9--i think) one on Manhattan's east side (felt 30 mile away) and one in lower Connecticut, and Ohio had one too.
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#18188
02/06/2001 9:17 PM
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Joined: Aug 2000
Posts: 3,409
Carpal Tunnel
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Carpal Tunnel
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we've had 2 earthquakes in the past 2 months-- both in the 2's (2.5 and 2.9--i think)
2s? Did you feel either of them? Anything less than 4.5 wouldn't even be noticed here, and I know people who have slept through 5s. My Dad was driving around town during our last signifcant shake, 6.4, and when he got home and was asked about the quake, he replied "what quake?"
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#18189
02/06/2001 9:34 PM
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Posts: 347
enthusiast
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>My Dad was driving around town during our last significant shake, 6.4, and when he got home and was asked about the quake, he replied "what quake?"
I had a car like that once too, Max.
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#18190
11/18/2001 12:30 PM
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I've spent the morning viewing clips of lahar on a site below someone posted above, I think; if not, someone posted the link somewhere in a thread related to lahar. To the point, I searched out some pyroclastic terms that may be of interest to those interested in volcanoes. Many that I found I'll omit in deference to those who won't want an unusually long post: pyroclast-- Volcanology. an individual particle or fragment of clastic rock material of any size that is formed by volcanic explosion or ejected from a volcanic vent.
http://www.harcourt.com/dictionary/def/8/3/1/4/8314100.html
pyroclastic ground surge Volcanology. the comparatively thin layer of rock of varying thickness found around a volcanic vent.
http://www.harcourt.com/dictionary/def/8/3/1/4/8314400.html
pyrogenesis Geology. 1. the intrusion and extrusion of a magma. 2. the products derived from a magma.the products derived from a magma.
http://www.harcourt.com/dictionary/def/8/3/1/5/8315400.html
pyroschist Petrology. a schist or shale with sufficient carbon to burn with a bright flame or to yield volatile hydrocarbons upon heating.
http://www.harcourt.com/dictionary/def/8/3/1/8/8318600.html
...now if I could just relocate the site that had the eerie photographs of pillow lava...
Oh, and here's the site that has the footage of lahar in action:
http://www.geo.mtu.edu/volcanoes/pinatubo/lahar/
WW
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#18191
11/18/2001 3:21 PM
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Volcanoes give us aa and pahoehoe
Two Hawaiian words. a'a is pronounced "ah-ah" and pahoehoe is Pah-HOY-hoy ... just in case anyone cares!
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#18192
11/21/2001 4:09 AM
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Posts: 866
old hand
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old hand
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a'a allegedly got its name from the sound made when the Hawaiins walked barefoot across an a'a flow. I kid you not.
stales
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#18193
11/21/2001 4:16 AM
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old hand
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wwh - there you go - right there - in the subject of this post....
We British Commonwealthers say 'geological'.
This spelling would make sense to Mr Spock (follow me on this one.........)
stales
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#18194
11/21/2001 4:39 AM
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old hand
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A couple of my favourites relate to glacial deposits.
Picture if you will, a glacier slowly melting - dumping its load of boulders and bits of rock all along its path, not just at its end (for the geologically inclined - not at its 'terminal morraine'). Occassionally a large boulder will drop where no other large boulders are to be found. Once the glacier has melted one is left with a flat terrain with large boulders scattered here and there. Perhaps the most common technical term used for these is "erratic blocks".
Unfortunately Dr Robin Wass at Sydney Uni in 1978 ruined my geological and political correctness for all time. His pet term was the spooneristic, "erotic blacks". Ever since, I've really had to concentrate in order to use the correct term.
Another term for these isolated boulders (some the size of a house) is "knockers".
Once, when attending a presentation on the geology of Greenland (where knockers are a regular feature), I couldn't help myself. Just had to put up my hand and ask of the presenter, "Dr Ridley - could you comment upon whether there is any cleavage associated with those knockers?"
A rock unit's cleavage (as opposed to a crystal's cleavage) is an important component that assists geologists establish the structural history of the area).
stales
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#18195
11/21/2001 6:42 AM
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Stales, don't leave us hanging over your cleavage. What was Dr. Ridley's reply?
Bingley
Bingley
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#18196
11/21/2001 3:29 PM
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you could almost feel it.
Anything less than 4.5 wouldn't even be noticed here
Whether one notices an earthquake depends not only on the Richter Scale level but also on the nature of the ground through which the shock waves are travelling. Earthquakes felt through the suspension of an automobile can be mistaken for shock waves from passing trucks.
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#18197
11/21/2001 7:57 PM
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Stales...You wrote:
A rock unit's cleavage (as opposed to a crystal's cleavage) is an important component that assists geologists establish the structural history of the area).
Crytal's cleavage isn't important to geologists?
And, on geologic and Dr. Spock: Would he prefer biologic, psychologic, anthropologic, and gang?
DubDub
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#18198
11/21/2001 8:08 PM
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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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#18199
11/21/2001 9:33 PM
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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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#18200
11/21/2001 10:04 PM
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Carpal Tunnel
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"Crystal's cleavage isn't important to geologists?" Show us a picture of Crystal!
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#18201
11/22/2001 6:01 AM
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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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#18202
11/22/2001 6:53 AM
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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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#18203
11/22/2001 11:43 AM
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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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#18204
11/23/2001 12:14 AM
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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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#18206
11/23/2001 2:45 AM
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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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#18207
11/23/2001 9:55 PM
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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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#18208
11/24/2001 10:59 PM
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Hello, Milum...
This wind is from the Old Dominion, Virginia. I enjoyed reading your dirt, but was dumb as dirt understanding it. A Wind is, but knows not from whence it comes.
For example, when you wrote, "Mammoth Wallow Hole" theory and the "Exploding Comet", all I could see was some prehistoric beast doing a cannonball into the Tar Pits...
But back to basics: Which is the heaviest of the minerals? And the lightest? I think talc is the softest on the mohs scale and diamond, the hardest.
WordWacker
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#18209
11/25/2001 9:26 AM
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old hand
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> Which is the heaviest of the minerals? And the lightest?
Great question dubdub!
I don't know if it's THE lightest (or, more correctly, that with the lowest specific gravity) but Evenkite would have to be right in there with a chance. It's SG of 0.87 (ie 0.87 grams per cubic centimetre) puts it in a class of its own in comparison to its nearest competitor (that I'm aware of) Sassolite (SG 1.45).
Evenkite is a rare mineral found only in the drainage area of the Tunguska River (former USSR) and at a couple of places in Czechoslovakia. It's a mixture of carbon and hydrogen (formula C24H50).
Mercury (the only liquid mineral at standard temperature and pressure) has the highest SG. At 13.6, it is also in a class of its own, the nearest competitor (Hessite - a silver telluride) has an SG of 8.4.
stales
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#18210
11/25/2001 2:37 PM
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Dear Stales: I was surprised by your statement that Mercury had the highest specific gravity: 13.6 I found a site about minerals that says Gold has a specific gravity of 19.3 http://mineral.galleries.com/minerals/elements/gold/gold.htm
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#18211
11/25/2001 3:41 PM
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Without stopping to LIU, I believe that osmium is the densest of the elements, and that each of its closely-akin elements is also more dense than gold.
As to the lightest mineral: stales, your post would indicate that only one mineral will float in water -- correct? I believe pumice also floats, albeit for a different reason (trapped air).
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#18212
11/25/2001 4:25 PM
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Carpal Tunnel
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How exciting! A triple heavyweight championship fight! In this corner, weighing in at 13.6 specific gravity, we have Mercury; in the opposite corner we have Gold, at 19.3; and, standing in between, we have Osmium at an indetermined weight, but he don't care! He's champing at the bit to knock ol' Feathershoes and Gildedlegs down!
The heavyweight championship prize? An evening out with cute little Evenkite, the airhead, who spends her time sunbathing on the shores of the Tunguska.
Bets regards,
WordWeight
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#18213
11/25/2001 4:33 PM
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Dear Keiva: to document correctness of your reply:
Osmium discovered in 1804. Bluish white in colour. Specific gravity over
21. The heaviest metal known. Associated with Iridium in alloys. ...
http://www.nandesign.com/metals.htm
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#18214
11/25/2001 5:01 PM
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Edit, after LIU:: gold is well below the most dense element, but the sources conflict slightly on the details: http://www.science.co.il/PTelements.asp?s=Density ranks osmium as the densest element, closely followed by related elements iridium, platinum and rhenium. Gold is 8th (or 6th if the trans-uranium elements are excluded), slightly behind tungsten (a/k/a wolfram). Another source places iridium slighly above osmium, and places gold slightly above tungsten. http://www.webelements.com/webelements/elements/text/Os/phys.html (see graphic, click to adjust it to "shaded table" format, and then scan cursor over it for pop-ups)
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#18215
11/25/2001 9:23 PM
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Joined: Mar 2001
Posts: 4,189
Carpal Tunnel
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Carpal Tunnel
Joined: Mar 2001
Posts: 4,189 |
For a fascinating look at Javanese volcanic sulphur mining in the new Smithsonian magazine click this link, and then click on Fire and Brimstone in the table of contents. There's also a great story for the paleontologically inclined, Whales on Mountains, about a fossil expedition to the Andes. The finds documented here help validate the theory that the Andes were among the fastest growing mountains in the world. These are, however, abstracts and not the full texts, but well worth a look anyway. http://www.smithsonianmag.si.edu/smithsonian/toccurrent.shtml
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#18216
11/26/2001 12:13 AM
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Joined: Nov 2000
Posts: 866
old hand
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old hand
Joined: Nov 2000
Posts: 866 |
We need to differentiate between elements, minerals and rocks - otherwise comparing SG's becomes an apples and pears exercise.
Gold and osmium are both elements - ie they only consist of one chemical entity each. Gold is also regarded as a mineral however - belonging to the 'Native Element' class of most classification systems. I don't think Osmium is found on its own in nature - it is found in platinum ores and as part of the mineral now known as "Iridium" - which has an SG between 19.3 and 21.1, depending upon its composition. Iridium - the mineral - actually consists of several elements combined to a greater or lesser extent but with Iridium - the element - dominant. Either way, Mercury is not the heaviest mineral and I apologise for taking y'all on that voyage up the garden path.
Evenkite would float on water (because its SG is less than water's 1.0) - but I believe it dissolves readily, so this will have to remain as a thought experiment.
Pumice does float on water but, as you surmised, this is due to its physical structure. Furthermore, it is a rock type - rocks being made up of two or more minerals - though technically one could call a lump of talc (frinstance) "talc rock". Minerals are made up of one or more elements.
stales
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#18217
11/26/2001 12:55 AM
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Joined: Sep 2001
Posts: 6,296
Carpal Tunnel
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Carpal Tunnel
Joined: Sep 2001
Posts: 6,296 |
Many thanks, Stales, for the clarification thus far. I've enjoyed the voyage up the garden path, and, being one who rarely sees the forrest for the trees, I didn't see the path for the rocks on it--or minerals in it...trying to be a passing student here.
So: Is gold, then, the heaviest mineral? Or is it Iridium (outweighing gold), even though Iridium pals up with other minerals? (I'm not trying to be dense as Iridium here.) And Evenkite is the lightest? If anything, it's been fun having my consciousness raised at least to recognizing what SG means, should I read it again, and understanding its meaning.
Heh! What's the Rock of Gibraltar composed of??? And the Blarney Stone??? I'll come back tomorrow and post a link to a terrific rock study that's going on in New York. Very impressive work they're getting out of those New Yorkers.
Best regards,
DubDub
P.S. Mebbe somebody could waterproof Evenkite with a substance that has an SG less than 1.0. You never know when there may be a need for floating Evenkite. Or change its physical structure so it'll float. Alert scientific minds can see though to future applications.... Evenkite Jet Skiis... used for strictly scientific research.
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