Submerged Continents and Ancient Civilizations

The tinwikie "Sunken Continents Series"
Atlantis - The orginal and still the best
Mu - What is now Polynesia was once ancient Mu
Pan - Forget the Alaskan Land Bridge, this is a whole continent
Lemuria - Of Primates and Blatvasky

All of these places, with the exception of Atlantis, were created in the modern era. Before plate tectonics was an accepted geological theory, scientists beleived that land masses rose from and sank into the oceans, periodically. Today, its recognized that continental crustal material cannot sink into oceanic crust, because its lighter. When oceanic crust and continental crust meet, the heavier oceanic crust sinks into the earth's mantle, where it is melted and destroyed.

Sometimes tectonic processes, over extreme lengths of time, cause continental crust to uplift, this can result in mountains. Dropping sea levels can also reveal underwater continental material.

But what doesn't happen is continental crust shooting up through the mantle, getting a civilization on it, and then being sucked back down through the oceans into the deep mantle, where it dissapears. If you look at the atlantic ocean basin, you find that there is no continental materia, the same with the pacific and indian basins.

Interestingly, perhaps the one place where a sunken continent hasn't been proposed, one does, sort of exist. Indonesia. These islands are infact the peacks of hills and mountains of a large mass of continental crust that is, today, submerged, because of rises in sea level.

Whats more fascinating is that this process seems to have occured in the timespan of man's existence, while people possibly lived upon it.

Hi there also thought i would maybe point out about glacial periods. Due to the huge weight of ice this can push land down which in turn brings land elsewhere up this is called the see saw effect. I know one example of this is Britain as the ice caps of scotland have been melting scotland is now raising and the south of england sinking. In extreme circumstnaces this could happen on a plate scale.

Originally posted by Nygdan

Interestingly, perhaps the one place where a sunken continent hasn't been proposed, one does, sort of exist. Indonesia. These islands are infact the peacks of hills and mountains of a large mass of continental crust that is, today, submerged, because of rises in sea level.

Whats more fascinating is that this process seems to have occured in the timespan of man's existence, while people possibly lived upon it.

Nygdan,

I first read about the sunken continental plate you mention here in Scientific American last fall. It was in a special issue called "The Changing Earth" or something.

Anyway, the continent in question "sank" because it drifted over the remains of an old subduction zone. The subduction zones originate where a continental plate is being forced over an oceanic plate, like you said. But the continental plates do not maintain a constant direction in their long-term motion. The areas where geologically ancient subduction zones were continue to "subduct" for some time after the plates are no longer forcing it. This is because the "slab" (a "slab" is what they call a plate once it's begun sinking into the mantel) continues to sink (of course) even after the continent has stopped forcing it. The sinking of the slab draws the surface down with it for a short time (geologically short - tens of millions of years) and anything that drifts over the zone will be pulled downward. The continental plate over that zone today is held under sea level by this subduction. Of course, with the sea level rise that occurred with the end of the last ice age, there is even more land underwater there than before.

The upshot is, this sunken continental plate drifted over the subduction zone millions of years before Homo appeared. While there may be some kind of ancient archaeology sites underwater there, they would certainly be limited to the portions of land that were above sea level during the last ice age. The rest of the plate was underwater not long after the dinosaurs disappeared.

Harte

This goes well with my question about Pannonian Sea. Watter from that sea had to go somwehere (rising the level of watter) and it all happened according to wiki 5.3 million to 1.8 million years before present.

Also according to wiki, At that time started drying of Mediterian sea.

All that watter had to to go somewhere...

Originally posted by Harte

Originally posted by Nygdan

Interestingly, perhaps the one place where a sunken continent hasn't been proposed, one does, sort of exist. Indonesia. These islands are infact the peacks of hills and mountains of a large mass of continental crust that is, today, submerged, because of rises in sea level.

Whats more fascinating is that this process seems to have occured in the timespan of man's existence, while people possibly lived upon it.

Nygdan,

I first read about the sunken continental plate you mention here in Scientific American last fall. It was in a special issue called "The Changing Earth" or something.

Anyway, the continent in question "sank" because it drifted over the remains of an old subduction zone.

The upshot is, this sunken continental plate drifted over the subduction zone millions of years before Homo appeared. While there may be some kind of ancient archaeology sites underwater there, they would certainly be limited to the portions of land that were above sea level during the last ice age. The rest of the plate was underwater not long after the dinosaurs disappeared.

Harte

Actually you're both right

Nygdan was referring to Sundaland - which the shallow contiental shelf around Indonesia which emerged as land when the sea levals fell during the Ice Age, and was subsequently drowned again when the ice sheets melted. There were almost certainly humans living there at the time.

However, long before then, a real 'continent' sank in the Indian Ocean - the Kerguelen Sub Continent - which as Hart explain, was formed as it passed over a mantle plume.

I'm surprised more isn't heard of Kerguelen as it it a scientifically accepted example of what most people think happened to Atlantis. Although it would have taken millions of years to sink....

I'm not sure if the Ontong Java Plateau - similarly formed by massive basaltic eruptions - may also have been a sub continent at one time as well?

Originally posted by Essan
...However, long before then, a real 'continent' sank in the Indian Ocean - the Kerguelen Sub Continent - which as Hart explain, was formed as it passed over a mantle plume.

Essan, the following article was written (I believe) by one of the authors of the Scientific American article I mentioned:
www.miracosta.edu...
It's a .pdf document, as you can see. Here's a link to an HTML version for those that don't want to download it:
www.google.com...:2bM61x1GBDsJ:www.miracosta.edu/home/kmeldahl/articles/sculpting.pdf+subduction+zone+submerged+continent&hl=e n&gl=us&ct=clnk&cd=18

That article contains the following statement:

Today Indonesia is a vast submerged continent—only its highest mountain peaks protrude above sea level

Scroll down near the bottom to read it, or use the "find" function in your browser.
The statement comes up in the context of the author's theory concerning the well-documented repeated rising and falling of elevations in Australia (he calls it "bobbing.")

This implied (to me) that Indonesia, rather than being sumberged by the ice age melt, is actually part of an entirely seperate and submerged continental plate. Of course, given Indonesia's location, it's depends on your particular preference regarding whether you want to call it the Indian Ocean or the Pacific. But I don't believe the BBC article you referenced is referring to this particular submerged continental plate. It (the Kurguelan) appears to be another plate, distinct from the Indonesian one. If so, I'd never heard of it, so thanks for the info.

Harte


[edit on 5/19/2006 by Harte]