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Re: Re: Temp in Cretaceous
>>I have to ask, where was Alaska at the time? I mean in the continental
>>positioning scheme during the Cretaceous. Was it farther south, north, east,
>>or west of the present position? Also, the surrounding ocean temps played a
>>role, didn't it? Global weather patterns surely were very different. Were
>>there not many more shallow seas, globally? What about Antarctic dino's? Was
>>it in the same place, vastly warmer, and so on?
> Out of curiosity, anybody know when the ice cap(s) first formed?
There have been several different periods of ice cap formation. The current
northern ice cap was probably not permanent year-round until about 2 million
years ago. During the Pliocene, for example, the Arctic Ocean was almost
certainly ice free during the summer.
Antarctica is more ambiguous, though. Some evidence points to a similar age
(c. 2 Ma) for permanent ice formation, other to 8 or more million years ago.
Given the ameliorating effects of oceanic highstands (say THAT 3 times
fast), the Cretaceous may have been ice free year round (except for mountain
Thomas R. Holtz, Jr.
Dept. of Geology
University of Maryland
College Park, MD 20742