Pre-Columbian settlement.

[Digit]

The usual reason given here in Europe is that there was a deluge of 'Biblical' proportions at some time in the past. If Einstein was correct in his assertions that the Earth's crust slipped we have the cause. It's worth noting (I read years ago, can't remember the source), that the Egyptians recorded a time when the Nile flowed South and that the sun rose in the West. I have a dislike of accusing our ancestors of being more stupid than some of us 'moderns' and tend to the idea that such a universal belief must have its roots in some factual event. Though having little faith in Atlantis, the usual reason for dismissing Plato's assertions is that such an event as he describes is impossible, this must be open to question I think.

[Charlie Hatchett]

Egyptians recorded a time when the Nile flowed South and that the sun rose in the West

Now that's a trip! Like the world flipped, or should I say slid, upside down since the time of which the Egyptians record .

If you can track that source down, it would be very cool to study a bit more.

[Minimalist]

and that the sun rose in the West

I'm glad you mentioned that, Digit. I seem to recall an interpretation of that comment, which more exactly was "the sun rises where it once set" as being a precessional reference. In other words, the Egyptians recorded that the sun, which once set in Leo(for example) now rose in Leo. Of course, this would mean that the Egyptians had made these observations through at least six zodiacal changes and that the sun's rising position ( it is now in Aquarius) had moved 180 degrees through the zodiac.

Thus that would mean that since it takes just under 2,200 years for the sun to move from one constellation to the next, the Egyptians were commenting on a history or stellar observations that was some 13,000 years old....and the Club has a shit fit with any suggestion like that, doesn't it?

[War Arrow]

It's worth noting (I read years ago, can't remember the source), that the Egyptians recorded a time when the Nile flowed South and that the sun rose in the West.

Can't help you with the wonky sun problem, but the river thing may have a precedent, in case anybody missed this from the news page:
http://www.newswise.com/articles/view/524511/

[Digit]

I wish I could Charlie but it was many years ago, as I remember it it was carved on the wall of a tomb. I can't, again, remember the exact wording Min but I'm sitting here scratching my head trying to work out whether or not your description would permit of the idea that the Nile had previously flowed South or not. Would it?
One of the things that has intrigued me for some years is the creation of the 'Badlands' in your country. As I understand it the ice melted behind the the leading edge of the ice cap to create the largest lake in recent times, till eventually the leading edge collapsed to create a virtual wall of water that flowed for some considerable time.
That leads me ask why? Why would the ice have melted first away from the more normal site, the leading edge of the ice? I can think of only two explanations, one, volcanic or geo thermal activity on a massive scale, or two, the crust did shift so as to bring the ice that was away from the leading edge into a position of greater solar radiation.
Although so many peoples have a story of a great flood we tend, I think, to make the mistake of assuming that they are all referring to a simultaneous event, but apart from the Biblical description their is really no reason why we should assume that these events occurred even within one generation.

[Minimalist]

That's exactly the logical problem I have with the "ice dam" theory...why would ice remain at the furthest edge of the glacial advance while a huge lake formed between the retreating glacier and the "dam." Suppose it wasn't an "ice dam" though. Suppose it was just the leading morraine pushed along by the glacier that formed an earthen/rock wall? Earthen dams fail all the time, anyway. Or, it could have been weakened by an earthquake. Seems more reasonable to me than "ice dams" but, I'm no geologist.

[Cognito]

It's worth noting (I read years ago, can't remember the source), that the Egyptians recorded a time when the Nile flowed South and that the sun rose in the West.

I believe the Egyptians recorded that directly after one of their drunken celebrations that Star was talking about earlier. Also, makes a good reason for not showing up at home the previous night ... "I was paddling home, dear, but the Nile was flowing in the other direction!"

[Roberto]

The Mississippi River is known to have flowed backwards in the late 1800's after an earthquake occurred. It only flowed northward for a very short time, but it is recorded. This was around the Memphis, Tenn. area where a major fault line crosses the muddy Mississippi.

[Digit]

I agree Min that sounds reasonable, but the Moraines in my area are no where near as high, nor can I find evidence, that they were ever as high as the ice behind them. If that's correct the lake that formed in the States would have had to have been lower in the middle than at the edge, ice fields cannot advance lower in latitude than the 32 degree thermocline, which leads me to another question. The Great Lakes event is probably the most studied, did the collapse occur somewhere along the 32 degree line or further North?
The thermocline would, logically, be further North on the coasts than inland, but in the case of the States the Rockies would have prevented a collapse on that side, but surely, all things being equal, the ice would have been thicker on the Eastern sea board than further inland due to increased precipitation. Also as ice reaches the 32 degree line it melts and this, in my area, appears to have prevented a long, continuous, Moraine from forming.
If my assumptions are correct the 'ice dam' theory, with all its faults, must hold.
Have we any geos in the forum? Perhaps they could help?

[Minimalist]

but the Moraines in my area are no where near as high

Today...after 20,000 years of weathering. What were they in 17,000 BC?


Besides, I seem to recall a concept...isostatic depression? or something like that. Anyway, the theory is that the earth's crust is pushed down by the weight of glacial ice and slowly rebounds once the weight is removed.

Geologists? Anyone help me out on that?

[Digit]

Hi Cog! I'm not sure if we are on the same wavelength here. I have always taken the idea of the Nile flowing South as meaning, not that it reversed its direction of flow, but that the Egyptian's perception of North/South changed. If you are looking downstream and the sun rises on your right, in the northern hemisphere, your are looking North, or whatever the Egyptians called it.
Using that as a basis how would you, as an Egyptian describe the river's direction if the sun now rose on your left?

[Digit]

Blimey we're busy tonight! Agreed Min, but all pwdered/small minerals have a natural angle of repose. Pour some salt into a heap and no matter how high the pile the included angle will always remain the same, therefore if a Moraine has weathered down there should still be evidence of the base having covered a greater surface area and from that, knowing the mineral content, the original height could be calculated.
In addition Min, in all the pictures I've seen of glaciers the Moraines did not reach to the top level of the ice.

[Minimalist]

If the ice was a mile high it would not have to reach the top to hit the 450 foot level.....in fact a little quick math indicates that the moraine would be only 1/12 the height of the glacier if the glacier was, in fact, a mile thick.

[Minimalist]

By the way, the natural "angle of repose" might apply to the outbound side but not to the glacier side. A bulldozer might be a better example.
Pushing (and compacting) whatever was in its inexorable way south until someone turns off the engine and it stops advancing.

[Cognito]

I seem to recall an interpretation of that comment, which more exactly was "the sun rises where it once set" as being a precessional reference. In other words, the Egyptians recorded that the sun, which once set in Leo(for example) now rose in Leo. Of course, this would mean that the Egyptians had made these observations through at least six zodiacal changes and that the sun's rising position ( it is now in Aquarius) had moved 180 degrees through the zodiac.

Thus that would mean that since it takes just under 2,200 years for the sun to move from one constellation to the next, the Egyptians were commenting on a history or stellar observations that was some 13,000 years old....and the Club has a shit fit with any suggestion like that, doesn't it?

Digit, I believe Min's explanation is the most reasonable, but I couldn't resist poking fun at Egyptian beverage rites. The Egyptian Nile's geology is quite different from the Mississippi basin and, as a matter of fact, it is my understanding that the Mississippi flowed north prior to the last series of severe glaciations.