No Relief for the Earth

by Richard Busch

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.

Copyright © 1993 by Fallbrook Gem and Mineral Society, Inc.

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).


Last updated: 18 September 2002