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Re: Ice Sheets Caused Massive Sea Level Change During Late Cretaceous

Cool! (pun intended) But if the ice sheets did not extend to the coast, how
are the dropstones in the plesiosaur calving grounds of Australia explained?


----- Original Message -----
From: "Richard W. Travsky" <rtravsky@uwyo.edu>
To: <dinosaur@usc.edu>
Sent: Monday, March 01, 2004 7:11 AM
Subject: Ice Sheets Caused Massive Sea Level Change During Late Cretaceous

> http://www.nsf.gov/od/lpa/newsroom/pr.cfm?ni=53
> Ice Sheets Caused Massive Sea Level Change During Late Cretaceous (Period
> was previously thought to be ice-free)
> ARLINGTON, Va.Scientists using cores drilled from the New Jersey coastal
> plain have found that ice sheets likely caused massive sea level change
> during the Late Cretaceous Period -an interval previously thought to be
> ice-free. The scientists, who will publish their results in the
> March-April issue of the Geological Society of America (GSA) Bulletin,
> assert that either ice sheets grew and decayed in that greenhouse world or
> our understanding of sea level mechanisms is fundamentally flawed.
> Led by Kenneth Miller of Rutgers University, the scientists examined cores
> from Ocean Drilling Program Leg 174AX, an onshore extension of an offshore
> expedition. They found indications that sea level changes were large (more
> than 25 meters) and rapid (occurring on scales ranging from thousands to
> less than a million years) during the Late Cretaceous greenhouse world
> (99- 65 million years ago).
> ...
> Analyses indicate minimal tectonic effects on the New Jersey Coastal Plain
> at this time, the scientists say. The other explanation for such large,
> rapid changes is the waxing and waning of large continental ice sheets,
> they maintain. What is perplexing, however, is that such large and rapid
> sea-level changes occurred during an interval thought to be ice free.
> "Our studies of cores in New Jersey provide one of the best- dated
> estimates of how fast and how much sea level changed during the greenhouse
> world of the Late Cretaceous," said Miller. "The Earth was certainly much
> warmer at that time, probably due to high carbon dioxide levels in the
> atmosphere. At the same time, our estimates require that ice sheets grew
> and decayed on Antarctica during this period of peak warmth, which has
> been a previously heretical view."
> The scientists propose that the ice sheets were restricted in area to
> Antarctica and were ephemeral. The ice sheets would not have reached the
> Antarctic coast, explaining the relative warmth in Antarctica, but still
> could significantly alter global sea level.