Topic 10 of 99: Orogeny and Diastrophism: Changing the Face of the Earth
Sun, Jul 11, 1999 (20:31) |
Marcia (MarciaH)
Mountain building and the deformation of the Earth's Crust forms mountains and ocean basins. The forces of nature at work.
57 responses total.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 1 of 57: Marcia (MarciaH) * Mon, Oct 18, 1999 (23:19) * 1 lines
This topic is so hot I though I should post something to make it a little cooler. Orogony is catastrophic mountain-building and land uplifting on a huge scale - as when the Indian sub-continent "slammed into" the Asian continent pushing up the Himalaya Mountain chain. On a geological time scale, that was an abrupt change. Diastrophism is the opposite.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 2 of 57: John Burnett (mrchips) * Mon, Oct 18, 1999 (23:25) * 1 lines
Which is the correct spelling of the former term?
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 3 of 57: Marcia (MarciaH) * Mon, Oct 18, 1999 (23:39) * 1 lines
Orogeny...sorry for the mistyping in the post! I shall try to be more careful on the diastrophism part...!
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 4 of 57: John Burnett (mrchips) * Mon, Oct 18, 1999 (23:50) * 1 lines
That shows your sense of humor runs pahoehoe hot.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 5 of 57: Marcia (MarciaH) * Tue, Oct 19, 1999 (00:10) * 1 lines
Thank you! (I am taking that as a compliment!)*grin* How do you like the new buttons? I see I have one missing...must rectify that immediatly!
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 6 of 57: Gi (patas) * Tue, Oct 26, 1999 (14:06) * 2 lines
(John)pahoehoe
What is that, pray?:-)
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 7 of 57: Marcia (MarciaH) * Tue, Oct 26, 1999 (14:10) * 1 lines
The fluid lava that spills out of the craters and runs down hillsides like rivers - see the Etna picture just posted. THAT is Pahoehoe lava. The clinkery stuff is a'a.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 8 of 57: Gi (patas) * Tue, Oct 26, 1999 (14:15) * 1 lines
I like what I think is the sound of pahoehoe :-)
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 9 of 57: Marcia (MarciaH) * Tue, Oct 26, 1999 (14:19) * 1 lines
pa HOEY hoey is the way it is pronounced with an European A (ah sound)
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 10 of 57: Gi (patas) * Tue, Oct 26, 1999 (19:27) * 4 lines
pah-HOI-hoi?
pei-HOI-hoi?
Nonr of the above?
:-)
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 11 of 57: Marcia (MarciaH) * Wed, Oct 27, 1999 (15:32) * 1 lines
pah HOI hoi us the correct way to say it!!! =)
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 12 of 57: Wolf (wolf) * Mon, Nov 8, 1999 (21:20) * 1 lines
like pah HOY hoy?
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 13 of 57: Marcia (MarciaH) * Mon, Nov 8, 1999 (22:18) * 3 lines
It works...*grin* Now we can all say a few words in Hawaiian, though it might be hard to work in to a conversation. a'a is "Ah Ah" with the stress being the same on each syllable.
Actually, Pahoehoe is more like "pa HO ee HO ee"...come to think about it. Five syllables in all.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 14 of 57: Marcia (MarciaH) * Tue, Nov 9, 1999 (16:17) * 14 lines
I guess Mass Wasting would fall in this category - huge land slips, avalanches of mud and other transport of large masses of terra not quite so firma...
(From Maggie)
At least 46 people were missing yesterday after an
avalanche possibly caused by volcanic activity buried
several dozen homes in a village in the North peruvian
Andes. The landslide buried parts of the village of
Tacabamba 500 miles north of the capital Lima on
Sunday afternoon. Some townspeople in the area say
these are thermal geysers that exploded and could have
been volcanic in nature. (A.P. Lima in The Guardian,
9.11.99)
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 15 of 57: Marcia (MarciaH) * Mon, Apr 17, 2000 (14:37) * 11 lines
In the space of one hundred and seventy-six years the Mississippi has
shortened itself two hundred and forty-two miles. Therefore ... in the
Old Silurian Period the Mississippi River was upward of one million
three hundred thousand miles long ... seven hundred and forty-two years
from now the Mississippi will be only a mile and three-quarters long.
... There is something fascinating about science. One gets such
wholesome returns of conjecture out of such a trifling investment of
fact.
-- Mark Twain
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 16 of 57: (sprin5) * Tue, Apr 25, 2000 (09:09) * 1 lines
I grew up on the Mississippi, what a powerful, brown, muddy river. What strong currents..
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 17 of 57: Marcia (MarciaH) * Tue, Apr 25, 2000 (13:45) * 4 lines
Dangerous for those who do not understand and respect her. The river is still carving out its "proper" course through the landscape and has a very wide flood plain. Folks just love to build farms on their fertile flood plains then let us pick up the bill to rebuild the place every so often when it gets washed away.
Big Muddy is just that, and I can feel the ooze between the toes...Yeesh!
There is an equally large river running beneath the Mississippi we can see, btw.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 18 of 57: Cheryl (CherylB) * Wed, Apr 26, 2000 (18:24) * 1 lines
If you ever fly over the Mississippi you can see the old river beds around the current one. I came across some information that due to flood control projects, among other things, the Mississippi Delta in Louisiana is now eroding back. The river no longer carries the same amount of silt to the Gulf of Mexico.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 19 of 57: World Builder (MarciaH) * Wed, Apr 26, 2000 (19:41) * 1 lines
Interesting. I'll check the internet and see if I can get some data and a picture like you describe. I also remember seeing it from the air. It was astounding!
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 20 of 57: Maggie (sociolingo) * Fri, Sep 15, 2000 (06:57) * 40 lines
Ancient trees may explain story of Atlantis
Marcia, I think this fits in here, feel free to cross post if you feel it fits elsewhere better :-)
Ancient trees may explain story of Atlantis
By RANDOLPH E. SCHMID, Associated Press
WASHINGTON (September 14, 2000 5:45 p.m. EDT http://www.nandotimes.com) - Researchers say ancient pine tree stumps found in a Swedish peat bog may hold a record of the great volcanic blast that some historians link with the end of the fabled Atlantis.
Using radiocarbon dating, a team of researchers determined that the trees had been alive between 1695 B.C. and 1496 B.C., and a study of their growth rings showed a four-year period of severely depressed growth about 1636 B.C.
Major volcanic eruptions have been known to blast enough dust into the atmosphere to cause frosts and limit crop growth, and one of the most powerful such blasts occurred when the Greek island of Santorini blew up in the mid-1600s B.C.
That disaster destroyed a culturally developed island and some historians believe it gave rise to the legend of the lost continent Atlantis.
"Our dating and the severe magnitude of this phenomenon suggest that it can be ascribed to the 1628-27 B.C. event, hence providing new evidence of a wider, more northerly area of influence," the team of Swedish scientists reports in the Sept. 15 issue of Geophysical Research Letters.
While the team led by Hakan Grudd of the Climate Impacts Research Center in Kiruna, Sweden, dated the Santorini blast to 1628, other scholars use different dates, though all are within a few years.
The Swedish team said their tree ring dating had a margin of error of plus or minus 65 years.
Other scientists studying tree rings have found periods of frost damage and slow growth in the mid-1600s B.C. affecting Irish, English, and German oaks, pine trees in California and trees in Turkey.
This is the northernmost evidence of an effect from the volcanic blast, the researchers said of the new Swedish find.
"The evidence is consistent with the hypothesis of a major Northern Hemisphere volcanic eruption in 1628 B.C., which may have been Santorini in the Aegean Sea," they concluded.
The climate impact of volcanoes has long been a topic of discussion, going back at least to Benjamin Franklin. The eruption of the Indonesian volcano Tambora was blamed for a worldwide cooling in 1816 - known as the "year without a summer" in New England, where snow fell in June.
Today Santorini is a popular tourist spot, where visitors can see the great caldera formed when the ancient volcanic island blew up and view excavations uncovering the remains of the ancient town.
The first mention of Atlantis occurs in Plato, who discusses an ancient island or continent destroyed by earthquakes and sunk into the sea.
Geophysical Research Letters is published by the American Geophysical Union, an international scientific society.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 21 of 57: Marcia (MarciaH) * Fri, Sep 15, 2000 (22:45) * 2 lines
Thank you so much for posting something in here. I love this topic, but it is just about impossible to find things to post other than long-winded lectures...
Mahalo again, Maggie!
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 22 of 57: Marcia (MarciaH) * Fri, Jun 8, 2001 (20:55) * 16 lines
I have no idea where this goes but here is as good as any place else. This is from Liam the Bountiful who has his nose to the grindstone and eat to the ground. Sounds uncomfortable but it is prodictive!
Another blow for all those stick-in-the-mud earth scientists
Robert Matthews investigates the origin of the oceans
IT is striking how some ideas refuse to die, long after
they've had the wooden stake of scientific evidence driven
through them. I am willing to bet that at least half of the
people gathered round the typical Sunday lunch table would
happily subscribe to the notion that eating chocolate causes
spots; getting soaked leads to colds; or that water goes
down the plug-hole anticlockwise in Britain (or the other
way around - it doesn't matter, it's still not true).
more... http://www.telegraph.co.uk/et?ac=004826292612046&rtmo=wK0ilwAb&atmo=rrrrrrrq&pg=/et/01/6/7/ecfmud07.html
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 23 of 57: Marcia (MarciaH) * Fri, Aug 17, 2001 (19:41) * 57 lines
Mountains on the Move: Geologists Study Active Fault in Wyoming's
Grand Teton National Park
JACKSON HOLE, Wyo., Aug. 6 (AScribe News) -- A team of geologists arrives in Jackson Hole, Wyo. this week to
continue studies of the movement of mountains.
"Are the Tetons getting higher? Or is Jackson Hole getting lower?" asks Arthur Sylvester, professor of geology at the
University of California, Santa Barbara. "These are the questions we seek to answer during our survey of the Teton fault this
summer."
The Teton fault, one of the largest active faults in Wyoming, is responsible for the uplift of the magnificent Teton Range in
Grand Teton National Park over the last eight million years, according to Sylvester. Since 1988, UC Santa Barbara teams have
been searching for minor fault movement, or "creep," along a 20 mile line of permanent bench marks across the park from the
Snake River into colorful Cascade Canyon.
By comparing results of repeated precise leveling surveys of the bench marks, the California geologists seek to determine if
the Teton Range is slowly but inexorably rising by minor, vertical displacement across the fault movement without the usual
earthquake activity.
The initial leveling survey was done in 1988 by Sylvester and his students in cooperation with researchers Robert B. Smith,
professor of geology, and his graduate student, John Byrd, both from the University of Utah.
Subsequent resurveys were done in 1989, 1991, 1993, and 1997 by Sylvester with UCSB and Utah undergraduate
students. Sylvester will also be assisted by Christopher Hitchcock, a UCSB graduate and who is now senior project geologist
for William Lettis & Associates.
This summer's surveying team includes several undergraduate students from UCSB and UC Davis, a retired civil engineer, a
retired US Navy officer, an Oklahoma State University graduate student in geology, a professional writer, and a high school
science teacher. These volunteers signed up through the University Research Expeditions Program (UREP) in Berkeley, Calif.
Sylvester found that, between 1988 and 1991, the valley east of the fault (Jackson Hole) rose ten millimeters relative to the
Teton Range. This was probably due to the rise of the water table caused by refilling Jackson Lake, eight kilometers north of the
leveling line. Additionally, the valley tilted toward the mountains.
However, between 1991 and 1993, to Sylvester's surprise, measurements indicated that the valley tilted slightly eastward,
away from the Teton Range. This is contrary to the long range tectonic tilt inferred from the slope of the valley floor and from its
subsurface strata.
At first Sylvester and Smith postulated that the uplift and tilting was caused by raising and lowering of the water table due to
the relatively rapid draining and filling of Jackson Lake. But the 1997 survey results resembled those of the 1989 and 1991
surveys, and the uplift of the valley near the fault increased another eight millimeters. The uplift of the valley, instead of the
mountains, implies that the Teton fault is back-slipping in response to regional crustal shortening. Global Positioning System
satellite measurements that Smith has acquired in both Grand Teton and Yellowstone National Parks in the past decade support
this hypothesis.
To test the hypothesis, Sylvester and his UCSB students extended the line of bench marks across the Snake River to the
Gros Ventre Mountains east of Jackson Hole. Thus the 2001 and future surveys of the line, now 26 miles long, will monitor not
only the behavior of the Teton fault relative to the adjacent valley, but also of the valley to the mountains on each side.
In the event of a major earthquake on the fault, numerical modeling of resulting displacements will allow Sylvester and Smith
to map the shape of the fault to a depth of about ten miles. Sylvester said this is a matter of great interest, dispute and concern,
given the existence of little data at present for this and other major faults in the western deserts and mountains.
Previous surveys have been supported by the National Science Foundation, the National Earthquake Hazards Reduction
Program, the National Park Service, and the Teton Science School.
http://www.ascribe.org/cgi-bin/spew4th.pl?fname=2001-08/20010806.095504&time=10:05+Pacific+Time&year=2001&public=1
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 24 of 57: Marcia (MarciaH) * Fri, Dec 14, 2001 (22:04) * 5 lines
Himalayan tectonics explained by extrusion of a low-viscosity crustal
channel coupled to focused surface denudation
C BEAUMONT, R A JAMIESON, M H NGUYEN & B LEE
http://www.nature.com/nlink/v414/n6865/abs/414738a_fs.html
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 25 of 57: Marcia (MarciaH) * Tue, Jan 15, 2002 (18:23) * 75 lines
Scientists Find Lowest Spot on Earth - the Dead Sea - Is Sinking Even Lower
By Andrew Bridges
The Associated Press
LOS ANGELES (AP) - The Dead Sea, already the lowest point on
Earth, is sinking even lower.
Areas along the shores of the Dead Sea subsided by as much
as 2.5 inches a year between 1992 and 1999, according to a
new study. The region on the Israeli-Jordanian border lies
about 1,360 feet below sea level.
The subsidence followed a drop in the water table around the
Dead Sea, allowing the ground to settle and compact,
according to scientists who published their findings in the
January issue of the Geological Society of America Bulletin.
Water that would normally flow into the Dead Sea has
steadily been siphoned off for agricultural and other uses
in the thirsty region. As a consequence, the level of the
body of water, among the world's saltiest, has fallen by
about 20 feet over the past decade.
The study used seven years' worth of data from a pair of
European radar satellites to examine changes in the level of
the ground along the southern and western shores of the Dead Sea.
By comparing high-resolution radar images of the same area
taken at varying intervals, scientists could pinpoint
movements of the Earth that otherwise would be nearly
imperceptible, unless the area was peppered with expensive
global positioning system receivers that can track the minute changes.
"You wouldn't be able to detect these things any other way,"
said David Sandwell, a co-author of the paper and a
professor of geophysics at the Scripps Institution of Oceanography in La Jolla.
The subsidence may be related, but only circumstantially, to
the gigantic sinkholes that have begun to appear along the
shores of the Dead Sea, a popular tourist destination, scientists said.
As the salt water of the Dead Sea recedes, in some cases by
hundreds of yards, fresh ground water replaces it. That
water then dissolves buried salt deposits, causing the
ground to collapse and threatening the stability of resort hotels.
Scientists believe a different mechanism explains the
larger-scale subsidence. They suspect that when the water
table drops in the area, the matrix of soils, sands and
gravels that held the water collapses behind it.
Gerald Bawden, a research geophysicist with the U.S.
Geological Survey in Menlo Park who was not connected with
the study, said the drop was hardly unusual given the
dramatic drawdown of the water table.
However, the areas seen to subside in the radar images were
just a mile or so in length, or smaller than he would have
expected, Bawden said.
In a paper published in August in the journal Nature, Bawden
reported that the pumping and recharging of ground water in
the Los Angeles basin causes the ground to rise and fall by
as much as four inches a year over an area 25 miles across.
Other studies have shown similar effects as groundwater is
removed and replaced in locations such as Phoenix and Las
Vegas. The radar technique used in the studies works best in
looking at arid areas free of vegetation that can skew results.
"We're just getting a first view of what the ground is
doing," Sandwell said.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 26 of 57: Michael McNeil (Weatherlawyer) * Tue, Jan 15, 2002 (19:28) * 7 lines
I was on a building site once where the land drain got crossed with the other drains in the system. This caused a culvert to rise quite a lot more than it should.
At the same time all sorts of problems were encoutered with the levels. The finished floor was many inches out of level by the time it was due for screeding, with resulting problems in the doorways.
The lift shaft was about 6" out of plumb too. Then they discovered the problem with the drains. When it was corrected a steam of water flowed through the inspection chambers for days.
I always wondered if it settled back. That all happened in just a year or less.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 27 of 57: Curious Wolfie (wolf) * Tue, Jan 15, 2002 (22:29) * 1 lines
welcome aboard michael! may i ask of the name "weatherlawyer"?
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 28 of 57: Marcia (MarciaH) * Tue, Jan 15, 2002 (23:25) * 3 lines
Mike, check Rob's nightmare scenarios in new Zealand on Geo 46. Your tale is one which is truly scary. Hilo gets deluges of biblical proportions occasionally and it washes out both roadways and houses (and the occasional bridge.) It sounds like the problems we have had in the past of poor zoning and planning. Just route the overflow around you. Then, someone builds a subdevision downstream from you and on the occasion of the "storm of the century" half of the subdivision washes away. We now have concrete-lined "stream beds" where the drainage is safely channeled into the sea. Your story sounds like parts of California near where my son lives. Does no one do geological studies until it is too late and lives have been endangered?!
It is wonderful to have you here! I'll answer your email right away!
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 29 of 57: Michael McNeil (Weatherlawyer) * Wed, Jan 16, 2002 (00:28) * 15 lines
Hi.
I don't know about bad building regs. but the above was an accident. Funny thing we broke for Christmass with the roof open. I remember telling the foreman that we couldn't leave it like that. He said it wasn't going to rain for 5 days. He was right. When we came back 5 days later it poured.
Everywhere was soaked. I'll never forget that.
I was in a flood once, a place in N. Wales called Rhyl. The Secretary of State for Wales used to rubber stamp planning permission for local builders if the local councils tried to stop them building.
Two weeks after the flood, he resigned and nobody said anything.
I saw one of those "red" tides there too. Not related to the flood. I don't think it was the same year even. It was the colour of blood. The smell was undescribable. It was just like rotting blood.
I seem to have drifted off topic.
Naughty Mike!
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 30 of 57: Marcia (MarciaH) * Wed, Jan 16, 2002 (00:53) * 1 lines
*HUGS* Mike! You're official now!!! Imagine you drifting off topic! Could you possibly share where you are? Hawaii has very srict building codes due to our earthquake potential. Lava flows are just another case of greed and stupidity. A realtor managed to get a parcel of land on the southeast rift zone. Mainland paradise-seekers came in and built lovely homes. 10 years later I consoled them on the loss of their homes while doing disaster relief work. Your guy should have been hanged by his proverbials!
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 31 of 57: Marcia (MarciaH) * Wed, Jan 16, 2002 (00:56) * 1 lines
WALES!!!! Croeso, Mike! Remember the coal tip that buried the school killing all those little children in South Wales? Princess Margaret brought TOYS to console the parents. I wonder what official managed to get that so wrong!
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 32 of 57: Marcia (MarciaH) * Wed, Jan 16, 2002 (01:03) * 3 lines
But, I suspect you are living or did live in Wales. If so, My day has been made complete! I have very fond feelings for Cymru and all things Cymraeg.
Talk about off-topic...
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 33 of 57: Marcia (MarciaH) * Wed, Jan 16, 2002 (01:10) * 1 lines
red tides...... they are noxious and dangerous, as you discovered. I thought they only plagued the east coast of North America! Hmmm... I have just the topic for that. Oceanic stuff is on Geo 36, but here is just fine, too.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 34 of 57: John Tsatsaragos (tsatsvol) * Thu, Jan 17, 2002 (05:51) * 11 lines
Hi Mike,
Welcome again. I see that humans are reacting in the same way around the world. We forget quickly and we live the same faults periodically. I cannot explain human disinterest some times. I think that we feel enough security until some nightmare comes to our door. Who will care for us? I think no one!
Tides are a monadic phenomenon that cannot be affected by the human activity. I know well that we can predict tides with great accuracy. I make such predictions using a computer program. It is useful tool in order to predict the time of an incoming EQ.
I want to give you any help you need and I can Mike. But forgive my not correct English some times. I feel you as friend even if you are long of me.
*Hugs*
John
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 35 of 57: Marcia (MarciaH) * Thu, Jan 17, 2002 (20:51) * 1 lines
monadic = single cause or singluarity. (You use very large words - but very precise ones. Greek is like that! I wish English was...!)
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 36 of 57: Marcia (MarciaH) * Thu, Feb 28, 2002 (14:49) * 41 lines
Portion of volcano slips toward ocean
STANFORD, California (CNN) -- In an event known as a "silent earthquake," a
72-square-mile chunk of the south slope of Hawaii's Kilauea Volcano slipped
3.5 inches toward the sea several months ago, leading one scientist to warn
of a possible disaster for Pacific Rim nations.
The slide, documented in the February 28 issue of the journal Nature, was
measured by Global Positioning System satellites in November 2000. A 12- by
6-mile area moved 3.5 inches over a 36-hour period in the first "silent
earthquake" ever recorded at an active volcano.
Such earthquakes are virtually undetectable on the surface, but can be
measured by GPS recordings. Since the GPS system is relatively new, there is
very little data on the phenomenon according to Peter Cervelli of the U.S.
Geological Survey. Researchers with the USGS and Stanford University tracked
the movement.
The 12- by 6-mile chunk that moved extends five miles into the earth's
crust, making its mass roughly equal to that of a quarter-mile thick, Rhode
Island-sized object, the researchers said.
An accompanying article in Nature by geophysicist Steven N. Ward, of the
University of California at Santa Cruz, speculates that a land mass that
size -- if it slid into the ocean in one cataclysmic event -- could trigger
an enormous tsunami that could imperil coastlines as far away as California,
Chile, or Australia.
A tsunami is a strong, fast-moving wave that can build to 100 feet high or
taller as it speeds into shallow water near the shore. Ward said his
computer models suggest that a massive slide at Kilauea could touch off an
arc of destructive waves in nearly all directions, with the greatest force
probably focusing toward the southeast, in the direction of Ecuador.
But Ward, and other scientists, caution that the tsunami risk is minuscule:
No such tsunamis of this type have taken place in recorded history. The last
such wave of which there is evidence occurred in Hawaii an estimated 200,000
years ago, he said.
http://www.newsindex.com/cgi-bin/resulttick.cgi?http://asia.cnn.com/2002/TEC
H/science/02/27/tsunami/index.html
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 37 of 57: Marcia (MarciaH) * Thu, Mar 28, 2002 (14:31) * 4 lines
Mars, Like Earth, Sculpted by Super Eruptions and Epic Floods
http://www.space.com/scienceastronomy/solarsystem/explosive_mars_020328-1.html
Explosive volcanic eruptions on Mars, fueled by the same stuff that makes your Pepsi fizz, fueled colossal floods that carved some
of the gorges and gouges found on the Red Planet, a new study suggests.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 38 of 57: Marcia (MarciaH) * Mon, Apr 8, 2002 (21:35) * 26 lines
The TEAYS River - Mid North America Before and After the Last Ice Age
The topography of North America was consider different from what it is now before the last ice age. The Great
Lake formed from the melting glaciers. There was temporarily a lake larger than all the Great Lakes combined,
called Lake Agassiz after Louis Agassiz, the discoverer of the phenomena of the ice ages. Lake Agassiz
developed due to river flows blocked by the glaciers. When lake Agassiz found outlets to Hudson Bay and Lake
Superior, as well as the Mississippi River, it mostly drained away, although there are the remnants called Lake
Winnipeg and Lake Manitoba left. The upper Missouri River drained into Lake Agassiz rather than following the
present channel.
The present Ohio River follows the southern edge of the glaciers. This channel was maintained even after the
glaciers retreated. Prior to the ice age the river drainage was along a channel through what is now the states of
Ohio, Indiana and Illinois. The Teays (taze) River in West Virginia follows the old channel until it intersects with
the Ohio River. The ancient river is referred to as the Teays River. Its channel can be seen in the map below.
Before the last ice age the Allegheny and Monongahela Rivers instead of flowing together to form the Ohio
River separately drained into Lake Eire.
The ancient Teays River disappeared on the surface, in part because of the moraines left by the retreating
glaciers, but underground the there is still a flow along the ancient river bed. A coal company in Indiana once sunk
a shaft looking for coal deposits. The site the company chose just happened to be over the ancient Teays River
bed. Instead of coal the company found water, lots of water. The company shortly changed its name to a water
company and started selling water to the surrounding municipalities.
diagram ... http://www.sjsu.edu/faculty/watkins/iceage.htm
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 39 of 57: Marcia (MarciaH) * Mon, Apr 8, 2002 (21:36) * 2 lines
I should save that diagram also but alas, it does not seem to be possible.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 40 of 57: Marcia (MarciaH) * Mon, Apr 8, 2002 (21:37) * 1 lines
I CLOSED that bold command TWICE. Ok...who is messing with me?
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 41 of 57: Marcia (MarciaH) * Mon, Apr 8, 2002 (21:38) * 1 lines
*sigh*
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 42 of 57: Marcia (MarciaH) * Mon, Apr 8, 2002 (21:57) * 20 lines
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The Teays River system originated long before 2 million years ago, in the Tertiary Period, and had
its headwaters in western North Carolina near Blowing Rock. It flowed northward across Virginia
and West Virginia, where its course is marked by the valleys of the modern New River (a misnomer,
as it is actually very old) and the Kanawha River. From St. Albans, West Virginia, the Teays flowed
westward to Wheelersburg, Scioto County, Ohio, and then northward to Chillicothe, Ross County.
This valley segment is dramatically visible on satellite imagery.
Chillicothe marks the southward limit of glaciation in central Ohio, and the valley of the Teays
disappears beneath glacial sediments (drift) at this point. However, by means of water wells and
other data, the buried Teays valley has been traced beneath the glacial drift northwestward across
Pickaway, Fayette, Madison, Clark, Champaign, Shelby, Auglaize, and Mercer Counties to the
Ohio-Indiana border. At the Ohio-Indiana border the valley of the Teays appears to be continuous
with a buried valley that has been traced westward across Indiana and Illinois, where it emptied into
an embayment of the ocean, now occupied by the Mississippi River. In Ohio, this buried valley is up
to 2 miles wide and in some areas lies beneath more than 500 feet of glacial drift.
more... http://www.ohiodnr.com/geosurvey/geo_fact/geo_f10.htm
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 43 of 57: Marcia (MarciaH) * Mon, Apr 8, 2002 (22:04) * 2 lines
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 44 of 57: Marcia (MarciaH) * Mon, Apr 8, 2002 (22:08) * 18 lines
Note the position of the Gulf of Mexico in the above map. As for Lake Tight:
THE END OF THE TEAYS AND CREATION OF THE OHIO RIVER
The earliest of three or more major glacial advances destroyed the Teays River system in western
Ohio. The edge of the glacier created a massive dam that blocked the northward-flowing Teays and
created a major lake in southern Ohio. The lake waters rose to an elevation of nearly 900 feet,
creating an intricate pattern of long finger lakes in tributary valleys. Numerous ridge tops poked
above the waters as islands.
This lake is estimated to have covered an area of nearly 7,000 square miles (modern Lake Erie has
an area of 9,910 square miles) in southern Ohio and parts of West Virginia and Kentucky. It is
named Lake Tight in honor of the pioneering study of the Teays system by Denison University
professor William George Tight (1865-1910). Lake Tight is estimated to have existed for more than
6,500 years as interpreted from seasonal layers in the sediment deposited on the lake bottom. This
lake clay is known as the Minford clay, named for a Scioto County community. It is mined in some
areas as a raw material for making brick and other ceramic products.
http://www.ohiodnr.com/geosurvey/geo_fact/geo_f10.htm
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 45 of 57: Marcia (MarciaH) * Mon, Apr 8, 2002 (22:14) * 8 lines
In recent years there has been debate among
geologists as to the course of the Teays across the
glaciated portion of Ohio. Some suggest that the deep buried valley in western Ohio that is
interpreted to be the valley of the Teays was formed by a meltwater stream flowing along the ice
front of an early glacier. These geologists prefer the explanation that the actual course of the
preglacial Teays River was northward through the central part of the state, where it connected with
a now-vanished ancestral system, known to geologists as the Erigan River, in what is now the Lake
Erie basin.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 46 of 57: Marcia (MarciaH) * Fri, Apr 12, 2002 (23:48) * 29 lines
Earth-Changing Drama... In a Geologic Heartbeat
The Pacific Northwest was the stage for one of the world's greatest scientifically documented floods. Little more than 12,000
years ago during the last throes of the Ice Age, a "finger" of the continental ice sheet reached south into the Idaho panhandle,
damming the mouth of the Clark Fork River and creating a monstrous lake known as Lake Missoula. Lake Missoula stretched
for hundreds of miles across western Montana and contained more water than Lake Erie and Lake Ontario combined.
The ice could only temporarily restrain such an immense volume of water. When the lake reached its maximum depth, water
burst through the ice barrier, shooting out of Clark Fork Canyon at a rate 10 times the combined flow of all the rivers in the
world. At that rate the lake would have drained in as little as 48 hours!
In a scene belonging more to the realm of science fiction than to reality, this towering mass of water and ice, over 2,000 feet high
at its source, literally shook the ground as it thundered toward the ocean at speeds approaching 65 miles per hour. The deluge
quickly stripped away 200 feet of soil and cut deep canyons or "coulees" into the underlying bedrock, creating a vast maze-like
network clearly visible from space. The torrent even widened and deepened the Columbia Gorge, baring the majestic cliffs
seen today.
Flood waters carved out over 50 cubic miles of earth, depositing much of it to create other unique landforms. Mountains of
gravel as tall as 30-story buildings were left behind, and huge boulders weighing more than 200 tons littered the ground like so
much flotsam. Fast-moving water shaped giant ripple marks 50 feet high. Recent studies of flood-deposited sediments yield
startling new evidence - the great flood occurred not once, but dozens of times!
Gone almost as quickly as they came, the floods left lasting marks across Montana, Idaho, Washington, and Oregon. Nowhere
else in the world do these types of landforms exist on the scale and grandeur found here in the Pacific Northwest. Yet most who
visit or live in the path of the floods know little about them or the enormous impacts they have had on our patterns of life. This
may be the greatest story left untold.
map
http://www.idahogeology.org/iceagefloods/iafidesc.html
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 47 of 57: Marcia (MarciaH) * Fri, Jul 26, 2002 (15:51) * 122 lines
New Evidence of Lava Dam Failure and Fault Activity Supports
Theory that Grand Canyon is Geologic Infant
Dams are not just a 20th Century phenomenon in Grand Canyon. As
early as 1882, geologists realized that the Colorado River was blocked
several times in the past by huge lava dams.
They theorized that these dams — formed when lava from volcanoes on
the rim flowed into the canyon — were slowly worn away as water flowed
over them.
But now geologists have found evidence that some of these dams didn’t
slowly waste away. Instead, some burst catastrophically — in one case
unleashing a massive flash flood carrying 37 times more water than the
largest ever recorded on the Mississippi River.
They also found that the Colorado River has been cutting down the eastern Grand Canyon twice as fast as the
western end due to fault offsets. This has formed what are essentially giant slot canyons in the Inner Gorge
(below the Tonto Plateau) and Marble Canyon. (Marble Canyon is on the Colorado River between Lee’s Ferry
and Desert View.)
This down-cutting happened so fast that it’s causing geologists to alter their estimates of the canyon’s age.
Growing numbers of geologists now believe that Marble Canyon and the Inner Gorge may be no more than
700,000 years old — veritable infants on the geologic time scale, and much younger than the earlier
3-million- to 5-million–year-old estimates. Some scientists now believe that a third of the canyon’s depth
may have been cut in the blink of a geologic eye — perhaps during the past 600,000 to 700,000 years.
In addition, much of the excavation may have happened during a
series of short, violent events that were linked by long periods of little
change. This runs counter to previous theories that say the canyon
formed slowly and continuously through uplift of the Kaibab Plateau
and steady, day-by-day erosion by water and wind.
The Hurricane and Toroweap faults, which cross the Colorado River
in western Grand Canyon, are the most active in Arizona.
Researchers at the University of Arizona, USGS and University of
Utah have found that both faults have been very active during the
past two to three million years, dropping in western Grand Canyon
and creating knickpoints that move upstream. Knickpoints can be
thought of as waterfalls that are formed when one side of a fault drops
lower than the opposite side.
Hikers walking the Bright Angel Trail can see a similar 200-foot
fault offset in the Coconino and Redwall layers. This offset created breaks in those formations that form a
natural route into the canyon on which the trail is built.
As the Colorado River flows over a knickpoint waterfall, it quickly erodes the streambed at the lip and the
knickpoint moves upstream. The greater the volume of water flowing over a knickpoint, the faster it cuts
upstream.
USGS hydrologist Robert H. Webb says there has been plenty of water flowing down the Colorado during the
past million years — much more than flows today.
Outwash from Rocky Mountain glaciers during the Pleistocene (2 million to 11,000 years ago) may have
generated flows in excess of a million cubic feet per second (cfs) because of the sheer volume of melting ice.
Historically, the largest flow recorded on the Colorado River was 300,000 cfs in 1884.
USGS scientist and University of Arizona graduate Jim O'Connor, along with UA hydrologist Victor Baker
and others, also has found evidence of a 400,000 cfs flow that occurred about 4,000 years ago. The only flow
that is comparable to Pleistocene flows would be if Glen Canyon Dam failed.
"Large sustained floods can cause rapid downcutting in bedrock," Webb said. The Inner Gorge and Marble
Canyon are essentially giant slot canyons: features consistent with rapid down-cutting, he noted.
George Billingsly, of the USGS in Flagstaff, found further evidence for a young Grand Canyon in the western
part of the canyon, just downstream of Havasu Canyon. His research suggests that solid rock stretched across
the canyon at the level of the Esplanade only 770,000 years ago. That means the Inner Gorge that now
drops 2,000 feet below the Esplanade was cut since that time.
More evidence of the age of the Inner Gorge comes from 600,000-year-old lava flows in western Grand
Canyon that lie near current river level in the vicinity of both the Toroweap and Hurricane Faults. If both
the 770,000 and 600,000 year dates are correct, the presence of these lava flows suggests that the river
may have downcut quickly in geologic terms.
While knickpoints and downcutting tell much of the story in eastern Grand Canyon, lava dams have been a
major force in the western part of the canyon.
Webb and University of Utah researchers Cassandra Fenton and Thure Cerling are finding evidence of
massive floods from failure of lava dams. They have recorded at least 5 major floods that occurred between
100,000 and 525,000 years ago after volcanoes erupted on the canyon’s rim, spewed lava into the gorge and
blocked the Colorado River.
These lava dams were inherently unstable because molten basalt met cold river water and rapidly cooled,
forming fragile walls of glass.
"When basalt hits water, it shatters into glass, and there is just glass all over the place in these deposits,"
Webb says.
When large dams fail catastrophically, such as
Idaho’s Teton Dam did in 1976, they leave
distinctive profiles in soils and on canyon walls. The
water drops quickly with an exponential decay
curve. "We have that curve preserved from a lava
dam that failed in Grand Canyon 165,000 years
ago," Webb says.
For this to happen, the dam had to fail almost
instantaneously. The Teton Dam, for instance,
failed in less than two hours. Webb estimates that
the resulting flows from the lava dam were up to 15
million cfs, — 37 times larger than the largest known Mississippi River flood. "These were some high dams,"
Webb says. "We estimate some were more than 1,500 feet tall."
Because the dams were unstable, the lakes that formed behind them had short life spans. Webb believes they
filled quickly under pressure from large flows of Pleistocene snowmelt. These reservoirs did not leave deltas,
which is consistent with this theory. Northern Arizona University scientists recently verified that the lakes
were short-lived, Webb added.
Webb, Fenton and Cerling collaborated on the fieldwork that supports this theory of catastrophic failure in
the lava dams. Webb is an adjunct faculty member in the University of Arizona departments of geosciences
and hydrology and water resources. Fenton will join the USGS and UA Desert Laboratory as a post-doctoral
scientist next month.
They applied a cosmogenic dating method developed by Cerling to date basalt flows and other landforms in
the Grand Canyon. The technique measures how long a surface has been exposed to cosmic rays from space.
Their application of this technique to lava flows in western Grand Canyon makes this region the best
understood in terms of the ages of volcanic features in the Southwest. Guided by Billingsley, they dated a
lava flow at 1,300 years old, making it of comparable age to Sunset Crater near Flagstaff as the most recent
volcanic features in Arizona.
http://uanews.opi.arizona.edu/cgi-bin/WebObjects/UANews.woa/1/wa/SRStoryDetails?ArticleID=5820&wosid=0x4mS9TeP2CQQjHUt6hpQ0
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 48 of 57: Marcia (MarciaH) * Fri, Jul 26, 2002 (16:17) * 46 lines
Heavy Bottoms Keep Old Mountains Down
As old mountains wear down, the tremendous pressure of
the molten mantle deep below pushes the peaks back
up--but not as much as it ought to. The reason, according
to a new study, is a bit of alchemy: The mountains' roots
slowly metamorphose into denser minerals. If geologists
can figure out the details, they'll better understand how
Earth's surface evolves.
Earth's crust floats atop the even denser mantle like a
skin of cream on milk. Mountains are roughly symmetrical
swellings in the crust: Their skyward-thrusting slopes are
counterbalanced by an equivalent, inverted mountain's
worth of mass underneath. As old mountains erode away,
they bob upward like icebergs with their tops melted off.
Mountains' roots rise too--but only to a certain point. In
many cases, a vestige of the roots remains even after an
ancient mountain range has eroded completely away.
Why the roots don't eventually level out with the rest of
the crust is a mystery.
The new study offers an answer. In the 27 June issue of
Nature, geologist Karen Fischer of Brown University in
Providence, Rhode Island, presents her analysis of
previously published gravity studies--which measure tiny
variations in gravity's pull across a region--and seismic
reflection experiments, which reveal the depth and shape
of the crust-mantle boundary deep underfoot. Fischer
combined these sets of data for young and old mountain
chains around the globe. After estimating the densities of
their crustal roots, she concludes that they remain
sunken because a geochemical process called
metamorphosis has converted them into denser minerals
as they cooled over hundreds of millions of years.
"The explanation is certainly plausible," says geochemist
John Eiler of the California Institute of Technology in
Pasadena. He says the findings fit with other current
thinking about the crust's nether regions and should
contribute to our understanding of how the lower crust and
the shape of the surface are related.
--MATTHEW BLAKESLEE
http://www.academicpress.com/inscight/06282002/graphb.htm
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 49 of 57: Marcia (MarciaH) * Sun, Jul 28, 2002 (18:18) * 5 lines
* Earth's early battering revealed *
Detailed analysis of the oldest rocks on Earth throws new light on one of our planet's most violent phases.
Full story:
http://news.bbc.co.uk/go/em/-/hi/english/sci/tech/newsid_2149000/2149215.stm
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 50 of 57: Marcia (MarciaH) * Tue, Oct 11, 2005 (00:57) * 9 lines
This fascinates me. Check out Shiva Crater
The Shiva Crater is located in the Indian Ocean west of India. It was formed around 65 million years ago, the same time as a number of other impacts that are recorded in the K-T boundary.
The Deccan Traps are located in the theorized center of the crater, lending support to the idea that the traps were created by the impact event.
The crater is believed to be 600 km long and 400 km wide.
Concerning the Deccan Traps: http://en.wikipedia.org/wiki/Deccan_Traps
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 51 of 57: Curious Wolfie (wolf) * Tue, Oct 11, 2005 (17:37) * 1 lines
what, no pictures?
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 52 of 57: Marcia (MarciaH) * Tue, Oct 11, 2005 (23:40) * 1 lines
There are pictures but nothing much shows anything. The Deccan Traps are deeply eroded like the Grand Canyon in the US but it is all flood basalt. It looks like any old rock from a distance. Nice even horizontal layers. Shiva Crater is even more difficult since much of it is filled, eroded or just plain obliterated by plate tectonics.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 53 of 57: Marcia (MarciaH) * Tue, Oct 11, 2005 (23:48) * 2 lines
Pictures and intersting information about the Deccan Traps
http://volcano.und.edu/vwdocs/volc_images/europe_west_asia/india/deccan.html
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 54 of 57: Curious Wolfie (wolf) * Wed, Oct 12, 2005 (19:30) * 1 lines
that is waaay cool!
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 55 of 57: Marcia (MarciaH) * Sat, Oct 15, 2005 (17:21) * 4 lines
Yah, I thought so too :)
Lest we all run to prepare for Armageddon, the reason it seems like the world is self-desrtucting is that 24/7 media needs something to talk about. They scour news services for the smallest events and talk about them incessantly. They hyped the bad conditions in New Orleans so out of proportion that when reality hit, we were almost too numb to care anymore. Any world where people are foolish enough to build their dwellings on fault zones or flood plains is going to have increasingly serious destructive events. I could continue but you get the idea. We have out-populated the planet and now we are seeing a bit of natural selection going on. It has happened since Creation.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 56 of 57: geomancer (cfadm) * Fri, Jul 14, 2006 (14:36) * 14 lines
http://www.jamestown-ri.info/acadian.htm
Geological History of Jamestown, Rhode Island
Building New England
The Taconic and Acadian Orogenies
The land that became New England was added to the core of North America between about 465 to 400 million years ago.
Two island arcs, the Taconic and Avalonian, which had been moving northward from their places of formation near the juncture of South America and Africa impacted with Laurentia (Proto-North America). These long island chains also added land in Canada and Greenland and as far south as the Carolinas.
Orogeny is a geological term for the process of mountain-building. Orogenies are driven by collision of land masses.
Topic 10 of 99 [Geo]: Orogeny and Diastrophism: Changing the Face of the Earth
Response 57 of 57: Marcia (MarciaH) * Sat, Jul 22, 2006 (16:37) * 1 lines
The Hudson River was once a tributary of the Rhine, too I really enjoy paleogeography!
Geo conference 
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