Follow up (was RE: Ancient mountains)

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> FlxLandry@aol.com
>
> By the way, how quickly are mountains "brought down" by  erosion?

It depends on a number of factors: total volume uplifted, climate, tectonic 
situation for uplift, isostatic rebound (basically, the
more you erode a mountain range, the more it rises in response to balance out 
the deep root pushing down into the mantle), etc.  It
can be a couple million years, or it can be tens of millions of years.

> And is
> there any reason to believe ancient mountains could have been  higher than 
> modern
> ones, say, in Pangaea? If the supercontinent was the result  of multiple plate
> convergences, it should have had some really spectacular  ranges...

At least some people have proposed that the Euramerican-Siberian collision (see 
http://jan.ucc.nau.edu/~rcb7/300NAt.jpg) might have
produced ranges higher than the Himalaya. Not all agree, though.

                Thomas R. Holtz, Jr.
        Senior Lecturer, Vertebrate Paleontology
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
        Mailing Address:
                Building 237, Room 1117
                College Park, MD  20742

http://www.geol.umd.edu/~tholtz/
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
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