Geography Reference
In-Depth Information
Chapter 7
Giving Earth a Facelift
In This Chapter
Sculpting the planet
Making soil for plants and food
Depositing debris
Living with flood plains and sea shores
G
radational force,
whichwearsdowntheEarth'scrustandisthesubjectofthischapter,istheopposite
of
tectonic force,
which builds up the Earth's crust, and was discussed in Chapter 6. Indeed, you could
say a competition of sorts is going on between those two powerful and opposing sets of forces which
respectively wear down and build up Earth's crust, and thus create and alter the natural landforms that
give character to Earth's surface. Gradational forces may not have the cataclysmic pizzazz of earth-
quakes and volcanoes, but their results, as shown in Figure 7-1, may be truly grand.
Figure 7-1:
The
Grand Canyon is
a product of
gradational force.
Listening to the reactions of people who are seeing the Grand Canyon in person for the first time is
always extremely interesting. Some gasp. Some say, “I had no idea!” Others ask, “What's for lunch?”
Okay, so not everybody is mightily impressed.
But they ought to be! The beauty is spectacular,and the scale is grand. InGrand Canyon National Park,
the featured attraction is a mile deep and 10 to 18 miles across, rim to rim, depending on where you
measure from. By way of explanation,
carved
is a verb you see a lot — as in “The Colorado River
carved
the Grand Canyon.” Phooey. The river didn't
carve
diddly. Instead, it
carried away
every last
ounce of rock and soil that once occupied the space that is now the Canyon.
