Originally posted by kyle43
reply to post by Soylent Green Is People
Which question are you refferring too. I do not think a 6 mile deep, 2500 mile long chasm could be obscured by erosion. Could you explain how plate
Erosion on Earth could certainly obscure it over 3 billion years. That's a really, really long time. There have been whole swaths of land that went
from flat plains, to high and jagged mountains, only to be eroded back to nothing again easily
in 3 billion years (in fact several times have
mountain ranges have risen and eroded to nothing over 3 billion years time).
The features we see on the surface of the Earth today are very, very young. Many of those features weren't even around just 1 billion years ago, let
alone 2 or 3 billion years ago. Whole geologic features (such as mountain ranges, canyons, and oceans) have risen up, and gone away again many
different time in 3 billion years.
Whole areas that were once the surface of the Earth are now under the crust because land plates slide over and under each other in the span of 2 or 3
billion years. There have been at least five major ice ages in that time, one of them about 700 million years ago during which practically the whole
Earth was cover by ice sheets. Some ice sheets could be a mile thick, with all of that weight of the ice scouring the land beneath it.
The features on the Earth we see today are extremely young. The Grand Canyon began forming on 5 million years ago. That's a blink of an eye compared
to 3 billion years. The Rocky Mountains only probably raised up about 75 million years ago. Again, they are very young.
The Atlantic Ocean wasn't even around just a short 150 million years ago. The Atlantic Ocean could have formed 20 times over in the past 3 billion
years. In the middle of Africa today, there is a crack in the earth (the Afar Rift in Ethiopia) that will probably be an ocean in 300 million years
-- tearing Africa itself apart.
Scientist talk about "Pangea", the latest time plate tectonics allowed for a single "super-continent". But Pangea was ONLY THE LATEST super-continent
in a long history of super-continents, and was "only" 300 million years ago. If you go back 2 Billion years, there have been no less four different
cycles of the continents separating and coming back together again. That is to say that there has been four different times in the past 2 Billion
years that the Earth has changed so drastically as to go from separate continents to one super-continent.
A lot has happened on the surface of the Earth in 2 or 3 Billion years. There are probably no surface features that could have survived all that time
through all of the geological changes and erosion. Something similar to the Valles Marineris on Earth could have been erased in 2 or 3 billion
edit on 10/25/2012 by Soylent Green Is People because: (no reason given)