RE: Tectonic News

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

> From: Dora Smith [mailto:villandra@austin.rr.com]
> Sent: Sunday, December 11, 2005 6:16 PM
>
> I have a question, though.   How old is the Rift Valley?

Neogene, but I'm not sure of more than that. Some hunting in the tectonic and 
stratigraphic lit for East Africa would give you the
answer, though.

> Shouldn't the
> continent have rifted by now unless something happened to the rifting
> process?

?!?Why?  It's only the the early stages. That's like looking at a cocoon and 
assuming that something must have happened to the larva
to stop its metamorphosis, rather than it is a perfectly ordinary cocoon in the 
midst of metamorphosis. The Rift Valley remains
tectonically active.

And the other two limbs of the triple junction there (the Red Sea and Gulf of 
Aden) are not THAT much farther along in development:
only a few tens of kilometers of new basaltic crust across at most.

Tectonics takes time.

                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/
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