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Re: Late Cretaceous Arctic Climates

Y'all know that the configuration of the continents has historically impacted both the presence and amount of ice at teh poles, and worldwide climate.

Among other things.

Dora Smith
Austin, TX
----- Original Message ----- From: "Colin McHenry" <cmchenry@westserv.net.au>
To: <dinosaur@usc.edu>
Sent: Tuesday, July 28, 2009 8:43 AM
Subject: Re: Late Cretaceous Arctic Climates

David Marjanovic wrote:
Hang on a second. How much ice is necessary to account for the sea-level changes? Does that amount really necessitate inland ice, or are mountain glaciers (like those in southern Alaska which reach the sea through a temperate rainforest) enough to explain the sea-level changes and the Australian glacier sediments?

The sea level is supposed to have changed by 25 m, right? 22 m is the difference between today and 400,000 years ago when Greenland and West Antarctica were ice-free. Is there a way to distribute that much ice over the high-altitude and high-latitude mountains of the Early Cretaceous world?

David - maximum sea level depth for the GAB in the late EK is 100-150 metres (as far as we can tell). Regressions seem to have been total, i.e. sea levels fluctuated by at least 100-150m during the 4 (or maybe 6) transgresive cycles during the Australian EK. So, yes, that would be a lot of ice melt.

I don't have an explanation for this... Would the extra land mass near the south pole (i.e. a large part of Gondwana) possibly have allowed for proportionally extra ice formation compared to Recent Antarctica?

Colin McHenry Ph.D.
Computational Biomechanics Research Group http://www.compbiomech.com/
School of Engineering (Mech Eng)
University of Newcastle
NSW 2308

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