Pre-Columbian settlement.

[Digit]

Morning all! Like all good theorists we are trying to use logic to come up with ideas that explain a problem, it is after all, the only tool available to us.
An ice sheet of the size and thickness we are discussing would have been too thick to have melted from below due to heat in the rocks unless the rocks were themselves heated by some form of geo-thermal activity.
As any ice of that area must have existed behind its own Arctic Circle, ie, north in this instance, of the 32 degree thermocline, I can not see that liquid water would have existed on any mountains that protruded through the ice.
Apart from along the edges of the 32 degree line any precipitation would have surely fallen as snow.
I have to agree with the idea of using hot spots like the Hawaiian chain to show that the crustal slip could not have taken place, if at all, during human history as the oldest island is over 5 million years old.
A change in the sun's output could provide the heat energy, but without the north pole tilting south that could not have melted the ice other than at the 32 degree line, and as I see it, melting along the edge does not cause floods of 'Biblical' proportions.

[DougWeller]

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.

Krause discusses this at [/url]http://www.skrause.org/writing/papers/h ... .shtml[url]

The first problem comes from the concept of isostacy, which is “the balance or equilibrium between adjacent blocks of crust resting on a plastic mantle” (Plummer and McGeary, 1996, p. 521). As mentioned above, isostatic rebound would affect the rise or fall of sea levels, and ECD provides no acceptable solutions to this problem. Einstein’s claim in Hapgood (1958) that at a certain critical point, a slip of the earth’s crust is bound to occur due to an unevenly distributed icemass also fails to take isostacy into consideration. The earth’s crust is not rigid, as Einstein stated. Instead, as ice builds up on a landmass, that landmass is depressed an appropriate amount to carry the load. Greenland provides an excellent example of this process (Dyson, 1963, p. 103) Also neglected by Hapgood and Hancock when considering icemasses is the fact that under high pressure, ice becomes plastic, that is, it will flow in a viscous fashion. As a result, glaciers are not static sheets of ice, but rather moving bodies of ice, that expand outward (continental) and downhill (alpine). When glaciers reach the sea, they don’t simply continue to build up: pieces break off and form icebergs. Hence, between isostacy and the tendency of ice to flow plastically, the critical point mentioned by Einstein is never reached.

The whole concept of the lithosphere gliding over the asthenosphere “as the skin of an orange [...] over the inner part of the orange” (Hancock, 1995, p. 10) is misleading. Just as the lithosphere is not a rigid body, the asthenosphere is not as liquid as Hancock believes. Instead, it is composed of highly viscous rock, which, due to high pressure and temperature, behaves plastically (Plummer and McGeary, 1996, p. 425). The asthenosphere does act as a lubricating layer for the lithosphere, allowing it to move, but due to its highly viscous nature, it cannot permit the rapid, large-scale, motion claimed by ECD.

Our metaphor of the jig-saw puzzle for ECD also falls apart: not because of the ways in which plates interact, but because a jig-saw puzzle can only be moved easily in ways mentioned earlier if it is located on a table. On a sphere, problems are encountered. In a mathematical sense, there are several forms of symmetry in the plane. There is rotation around a point and reflection about a fixed line, for example. For a sphere there is only one type of symmetry: rotation about a fixed axis. Physically, this rotation causes different motion on the sphere near the poles than it does near the equator of the sphere. If the lithosphere were to rotate around an axis over the asthenosphere, one would expect greater torque and friction between the lithosphere and asthenosphere near the poles of rotation than further away from the poles. The concept of evenly displacing the jig-saw puzzle disappears when one considers the jig-saw puzzle on a sphere rather than on a plane. Assuming ECD takes place, it seems logical that near the poles of rotation there should have been some form of increased geologic activity, such as faulting or volcanism, due to increased friction between the lithosphere and asthenosphere. However, neither Hancock nor Hapgood ever cover this point.

A final nail in the casket for ECD might very well be the existence of hot spots, which are areas of “volcanic eruptions and high heat above a rising mantle plume” (Plummer, 1996, p. 521). Yellowstone National Park, for example, sits on one such hot spot. Since the existence of a hot spot rests upon presence of a mantle plume, ECD would cause a dramatic shift in the locations of such hot spots. However, since evidence shows Yellowstone to be a very old hot spot, this weakens the possibility of such a shift due to ECD occurring.

Earth Crust Displacement appears to be unable to answer important geologic questions, and indeed, it seems to go against accepted geologic knowledge. Once the evidence is considered, Graham Hancock’s claim that ECD is compatible with plate tectonics no longer seems viable. Not only is Hapgood’s ECD theory lacking supporting geologic evidence, it actually contradicts tested geologic concepts.

skipping a paragraph, he then concludes:
It is also important to critically analyze what is being said and by whom. Hapgood was a historian, not a geologist, and Hancock is a writer with no credentials in cartography, archaeology, or geology. It is then no wonder that for so long ECD has been ignored by the scientific community. At the same time, however, there is definitely the need for science to stay open to new ideas. There are basically two views of how science progresses: either “through the gradual accumulation of discoveries and inventions” (Hallam, 1973, p. 106) or by paradigm replacement: the replacement of one world view with that of another. In a way, global plate tectonics seemed to be a new paradigm when it was brought forth. In retrospect, it seems only natural that it grew out of continental drift and sea-floor spreading. This revolution in scientific thought, just like that of Einstein’s Relativity, should reinforce the dangers of orthodoxy and dogma in science and the need to consider the method of multiple working hypotheses. Science is empirical: its theories are dependent upon gathered evidence: not the other way around.

In the case of Hancock’s book, perhaps more research needs to be done. Perhaps most geologists agree that Antarctica has been ice-covered for millions of year, but what if there is irrefutable evidence showing the presence of rivers in Antarctica a mere 6,000 years ago? Can they be explained by some sort of interglacial period, or is it necessary to rethink out ideas about Antarctica? Although Earth Crust Displacement seems non-viable, it still raises interesting question for geology and other fields.

Hancock ends Fingerprints of the Gods with a warning of impending worldwide destruction and a second occurrence of Earth Crust Displacement. Indeed, his arguments are no more novel than those of the Neptunists and Catastrophists in the past. We may remain unconvinced by his theories, but at the same time, we have not actually found alternative answers to his questions. Perhaps someday there will be a newer, better theory to explain Hapgood’s ancient maps and truth about Atlantis. Until then, however, all we can do think critically about what we learn, ask questions, and ponder these mysteries whose answers have eluded humans for ages.[/url]

[stan]

Minimalist posted a link to Krause a few days ago as a homework assignement....

So, Doug, what do you think about ice dams and melting glaciers?

[Charlie Hatchett]

Firestone has a hypothesis set forth: Remnants of a supernova peppered the earth, starting around 16,000 B.P. up to about 13,000 B.P.

http://cayman.globat.com/~bandstexas.co ... ticle1.pdf

The event is hypothesized to have triggered major glacial melting, and resultant flooding. Might also explain the melting in the middle of ice sheets..main impact zones.

[Digit]

Well Charlie that seems to be the answer to the Maidens Prayer, my wife made the same suggestion and I asked where the evidence was. Now we know, but! does that mean, that all other things being equal, the northern hemisphere's natural state is ice covered, if so roll on global warming?

[Charlie Hatchett]

Well Charlie that seems to be the answer to the Maidens Prayer, my wife made the same suggestion and I asked where the evidence was. Now we know, but! does that mean, that all other things being equal, the northern hemisphere's natural state is ice covered, if so roll on global warming?

Man, I'm gonna have to chew on that for a while...good point...

[Cognito]

Morning all! Like all good theorists we are trying to use logic to come up with ideas that explain a problem, it is after all, the only tool available to us.

Actually Charlie, Min and I both agree that Bush is retarded. Back to the original topic, the Mississippi. See this for the chronology of the Lake Agassiz flood in your direction:

http://www.eeescience.utoledo.edu/Facul ... Mexico.pdf

Min will look at the illustration and say, "See, the water is forming at the sides of the Laurentide Ice Sheet!", while I'll say, "See, there is an ice dam blocking the exit!" We'll probably need to meet in Greenland with boxing gloves to work this one out in a mature manner.

[Minimalist]

Remnants of a supernova peppered the earth, starting around 16,000 B.P. up to about 13,000 B.P.

Did the other episodes of glaciation in earth's 4.5 billion year history (sorry, Arch!) require supernovas to end, too? That seems like a lot of supernovas.

[Minimalist]

We'll probably need to meet in Greenland with boxing gloves to work this one out in a mature manner.

I'm ready!

[Charlie Hatchett]

We'll probably need to meet in Greenland with boxing gloves to work this one out in a mature manner.

The Western Division Finals!!

[Charlie Hatchett]

Actually Charlie, Min and I both agree that Bush is retarded.

Well, that's about the only mainstream statement I've heard around here in a while.

[Beagle]

Yep! Good points all. But we are still left with the original question that we are no nearer resolving. How does an ice sheet several miles thick melt in its centre? Anyone got any ideas on that?

Sorry for popping in and out of this discussion folks. Things will return to normal next week.

Here's what I think. We know that glaciers during the LGM were well over a mile thick. This weight actually deforms the earth and creates a depression. When the ice is gone the earth rebounds back to it's original shape. So the glacier makes it's own bowl, in a sense.

When the climate becomes warmer, during the summer, the suns' energy will be absorbed most readily by those surfaces that it hits directly, or in a perpindicular fashion. So the "walls" of the glacier will not be affected as much as the flat interior. Thus creating a lake.

If you set an ice cube out on your kitchen counter, it will melt uniformly.
If you set an ice cube out in the midday summer sun, the top center part of the cube will melt first. We can try it next July.

That's my guess.

[Charlie Hatchett]

Did the other episodes of glaciation in earth's 4.5 billion year history (sorry, Arch!) require supernovas to end, too? That seems like a lot of supernovas.

Man, we're all talking thousands of years here (16,000-13,000 B.P.). I can't even begin to extrapolate over billions. I'm only brainstorming on this event for now. I'm already confused enough.

[Digit]

Sorry Beagle but I can't follow that line at all. Sure, the land is depressed by the weight of the ice, here in the UK the whole island is tilting back at a rate that can be measured over recorded history, but the sinking of the land must be reasonably proportional to the weight above it, so if a depression forms in the centre the movement of the ice should fill it in. Glaciers move down hill, if they hit a barrier the height of the ice must rise till it clears the top of barrier, or it will remain static, when the ice clears the top ice flow can then start grinding the barrier down, therefore an icefield must on average be higher in the centre than at the edges.
I keep beating the drum about the 32 degree thermocline, but ice cannot pass it other than by a small amount due to local lowering of the air temperature due to the mass of the ice, therefore the temperature to the north of the ice field's leading edge must have been lower that 32 degrees, therefore no liquid water without the existance of another factor.

[Beagle]

http://en.wikipedia.org/wiki/Ice_dam

Sometimes a glacier flows down a valley to a confluence where the other branch carries an unfrozen river. The glacier blocks the river, which backs up into a lake, which eventually overflows or undermines the ice dam, suddenly releasing the impounded water.

I still think my ice cube analogy has merit, but it seems Google has the answer after all.