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Climate Change Was Major Factor In Erosion Of Alps 6 Million Years Ago

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Odin2005 Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Aug-21-06 01:45 PM
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Climate Change Was Major Factor In Erosion Of Alps 6 Million Years Ago
http://www.sciencedaily.com/releases/2006/08/0608151622...

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The Alps, the iconic rugged mountains that cover parts of seven European nations, might have reached their zenith millions of years ago, some scientists believe, and now are a mere shadow of their former selves. New research offers an explanation.

A team led by Sean Willett, a University of Washington geologist, has found that the culprit is likely massive erosion, triggered by a sudden drop in the level of the Mediterranean Sea 6 million years ago and then prolonged by a warmer, wetter climate.

EDIT

"At one time what is now Milan would have been in the foothills of the Alps," he said. "But the Alps never regained the size they had at the end of the Miocene."

EDIT

Before the massive erosion, he said, the Alps likely were 60 to 120 miles wider than they are today, and 1,000 to 5,000 feet higher. The highest point today is Mount Blanc on the border of France and Italy, at about 15,700 feet. It is likely that erosion took a toll on the northern edges of the Alps as well, Willett said.
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dipsydoodle Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Aug-21-06 02:07 PM
Response to Original message
1. Can't grasp some of the guy's figures
Edited on Mon Aug-21-06 02:08 PM by edwardlindy
For example : "Evaporation greatly reduced the water level, dropping it as much as two or three miles below the rest of the world's ocean surfaces"

The Med is only just over 3 miles deep at its deepest - would only have been a relative puddle.

" massive erosion, triggered by a sudden drop in the level of the Mediterranean Sea 6 million years ago and then prolonged by a warmer, wetter climate."

The second statement makes the first statement above even less likely.
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Xithras Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Aug-21-06 03:38 PM
Response to Reply #1
2. The Med was a canyon at one point.
The theory that the Med once dried up has been around since the 1960's and has a LOT of evidence backing it up. We've even found remnants of saltdomes and the hypersaline lakebed at the bottom.

Basically, the Straits of Gibraltar slammed shut at one point, and the Medditeranean evaporated. Because evaporation levels in the Med are so high, this process would have only taken a few thousand years. The only thing left would have been a small salt sea at the bottom. The situation really isn't all that different than Lake Bonneville/Great Salt Lake in North America. One big lake dried up, leaving only a small, super salty puddle behind.

Can you imagine what the waterfall must have looked like the day the Atlantic broke through again? It must have been an amazing sight. Even the regular waterfalls, as waterways like the Tiber or the Nile plunged over the continental shelves into the canyon below, must have been awe inspiring. Too bad there weren't any humans around to see it yet!
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Nihil Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Aug-22-06 03:05 AM
Response to Reply #2
3. Correct
In addition, the rate of evaporation today exceeds the gain from
river inflow so it is only the net inflow through the Straits of
Gibraltar that keeps the level where it is.

I suspect that the Atlantic "breakthrough" would have been very
gentle at first, gradually eating its way down, but the falls
from the Nile, Rhone, Tiber etc. must have been a sight!
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Xithras Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Aug-22-06 01:39 PM
Response to Reply #3
5. Actually, the "slammed shut" thing wasn't serious. It was an uplift event.
As I understand it, the current leading theory isn't that they really "slammed shut", but that the whole North Africa/Southern Europe/Med region was temporarily uplifted by a collision with another plate (that doesn't exist anymore). It lifted the western med enough to raise the bottom of the Straits above sea level, cutting it off from its water source. As the collision ended, the region gradually settled down again, allowing the sea to fill the basin. There still would have been a spectacular waterfall as the seawater plunged into the canyon for the first several weeks though.

I once had someone argue that we KNOW humans will never invent time travel because if we did, we would have already met time travellers. Things like this make me doubt that assumption...there are FAR more interesting things to look at than boring, money obsessed 21st century humans.
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dipsydoodle Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Aug-22-06 05:22 AM
Response to Reply #2
4. Thanks for that
For any other morons out there like me this helps elucidate : http://en.wikipedia.org/wiki/Messinian_Salinity_Crisis
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Odin2005 Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Aug-22-06 05:22 PM
Response to Reply #2
6. I wonder how high the air pressure was at the bottom of the basin.
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