Lithosphere (April 1993);
Fallbrook Gem and Mineral Society, Inc.; Fallbrook, CA

Just how much relief does the Earth have? I mean, suppose that
someone gave you a two-foot diameter sphere and a bucket of modelling
clay and told you to construct a three-dimensional, exact scale model
of the Earth. How much clay would you have to slather on the sphere
in order to accurately model the Earth's mountains? Would you have
to put on a quarter of an inch thickness of clay? Half an inch? One
inch? More?

Time to yank out the old geography book. Let's see ...
The radius of the Earth at the equator is 3,963 miles.
The radius of our model Earth is 12 inches. The elevation
of the highest mountain on Earth, Mount Everest, is 5.5
miles. So how high will our model Mount Everest have
to be?

Uh-oh, this looks like a job for (*gulp*) proportions! Ok,
one step at a time: 3,963 miles is to 12 inches as 5.5
miles is to x inches. Solving for x we get:

x = ((12)(5.5))/3963 = 0.017 inches

That's only 1/60 of an inch! Kind of hard to believe,
especially if you're standing next to Mount Everest, but
it's true. The Earth is actually so smooth that it only
takes a light smear of clay on the surface of a two-foot
diameter globe to accurately model the Earth's mountains.
I guess we'll just have to look at someplace other
than the Earth for relief.

The preceding article was originally published in the April 1993
issue of Lithosphere, the official bulletin of the
Fallbrook [California] Gem and Mineral Society, Inc; Richard Busch
(Editor).

Permission to reproduce and distribute this material, in
whole or in part, for non-commercial purposes, is hereby granted
provided the sense or meaning of the material is not changed and
the author's notice of copyright is retained.

Last updated: 18 September 2002
http://geopress.rbnet.net/relief.htm