Posted on Sunday, July 01 2007 @ 9:02 CEST by Thomas De Maesschalck
Scientists
report hot spots in Earth's top layer are keeping the continents afloat:
It has long been known that the continents float atop the denser rock of the underlying mantle, like foam on a hot tub.
It was presumed that this was simply because they are made of lighter types of rock. However, it turns out that about half of the buoyancy on solid Earth is provided by hot spots.
In these warm regions the rock expands from the heat, making it even less dense than would otherwise be the case.
Without the heat, scientists say, even Denver, Colorado—the Mile High City—would be below sea level.
The scientists calculated the difference in elevation for a couple of cities:
New York would be 435m below sea level instead of 10m above
New Orleans 736m below sea level instead of 0m
Chicago 679m below sea level instead of 179m above
Las Vegas 1,070m below sea level instead of 610m above
Los Angeles 1,145m below sea level instead of 106m above sea level.
