July 30, 2007
Hot Earth Keeps American Cities Above Sea Level

Think you stand on solid ground? Not so. Cooling down in Earth's core would sink most American cities under water.

A University of Utah study shows how various regions of North America are kept afloat by heat within Earth’s rocky crust, and how much of the continent would sink beneath sea level if not for heat that makes rock buoyant.

Of coastal cities, New York City would sit 1,427 feet under the Atlantic, Boston would be 1,823 feet deep, Miami would reside 2,410 feet undersea, New Orleans would be 2,416 underwater and Los Angeles would rest 3,756 feet beneath the Pacific.

Mile-high Denver’s elevation would be 727 feet below sea level and Salt Lake City, now about 4,220 feet, would sit beneath 1,293 feet of water. But high-elevation areas of the Rocky Mountains between Salt Lake and Denver would remain dry land.

“If you subtracted the heat that keeps North American elevations high, most of the continent would be below sea level, except the high Rocky Mountains, the Sierra Nevada and the Pacific Northwest west of the Cascade Range,” says study co-author Derrick Hasterok, a University of Utah doctoral student in geology and geophysics.

“We have shown for the first time that temperature differences within the Earth’s crust and upper mantle explain about half of the elevation of any given place in North America,” with most of the rest due to differences in what the rocks are made of, says the other co-author, David Chapman, a professor of geology and geophysics, and dean of the University of Utah Graduate School.

Will cooling of the Earth's core progress enough to some day sink lots of cities before the Sun expands and cooks away the oceans?

Share |      Randall Parker, 2007 July 30 11:14 PM  Trends Geology

rsilvetz said at July 31, 2007 6:37 AM:

If we make it thru the approaching transhumanist singularity, remind me in 100 million years.

David A. Young said at July 31, 2007 9:17 AM:

I wonder how much of the Earth's internal heat is due to the collision that ejected the moon? If it's a significant amount, then REALLY watery worlds might be the norm. Which would not be an encouraging indicator for the presence of intelligent stellar neighbors.

dave.s. said at July 31, 2007 11:35 AM:

This study is well reported to get maximum ink. I kind of think, though, that if our mantle cooled, so would the mantle all over the world, and we would all - continents and sea bed alike - go down together, leaving things not very different from how they are today, but a slightly smaller world. Is there some reason I ought not think that?

RobM1981 said at July 31, 2007 12:01 PM:

I'm not sure if that was factored into the analysis. The volume of the oceans would still have to find a home, even if the mantle beneath them was shrinking along with the mantle currently on land. If you shrink the mantle of the ocean floor, the water is going to need to "come up the sides" a bit more. I'm not sure if this "a bit" is what puts NYC 1,500 feet into the drink, or not...

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