Re: Erosional rates


"Jo Schaper" <joschapern4ospam@xxxxxxxxxxxxxxxxx> wrote in message
news:12798vtocorpjb4@xxxxxxxxxxxxxxxxxxxxx
Eigenvector wrote:

Question for the geologists here.

Is the rate of erosion greater or lesser or equal to the rate of build?

Let me qualify that in my terms. When I look at the shoreline, the
mountains, and such I consider the shoreline to be the zero plane of
usable land. So when I look at the mountains and hills and such I wonder
if the speed at which they are produced is greater than the speed at
which rain, wind, and gravity wear them down. I don't mean a specific
hill or mountain, but ALL hills and mountains - one might get ground down
in Asia only to be built up in Africa for instance. Obviously I'm using
generalizations here, so ultimately my question is - is the earth fated
to be a flat ocean or can plate techtonics keep up?

I suggest you do a web (and book) search on William Morris Davis and his
cyclic geomorphological theory (generally replaced by process
geomorphology in the 1950s) and geosynclinal theory (geological theory du
jour before plate tectonics.)

Now, I'm not advocating either of these answers, but they went into great
detail about how the process you are describing occurs. Trouble was, they
had no real mechanism for the uplift part of the equation. If you don't
understand them, you cannot see how plate tectonics answers some of their
questions.

Suggest also a look for these people: Arthur N. (AN) Strahler, and Grove
K. (GK) Gilbert, an early geologist of the American West, whose work was
revived by Strahler.

From a continental viewpoint, plate tectonics still does not answer all
the geomorphical questions raised by the people and theories above because
of the problem of scale. PT is largely a 'big picture' theory and the
questions asked by geomorphology are often smaller scale problems.

Whew, that was bit much for me, but I got the gist of the matter. It dealt
mostly with water erosion, but it should still be applicable for wind - wind
is a fluid just like water.



.

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