Devils Postpile: When the Geometry Is the Story
Near Mammoth Lakes, California
About nine miles west of Mammoth, at the end of a shuttle-bus road through the Inyo National Forest, there is a wall of basalt columns that look as though someone designed them.
Nobody designed them. That is the point.
Between ninety thousand and one hundred thousand years ago, a lava flow from the Long Valley volcanic system pooled in a canyon here and cooled slowly. Very slowly, by geological standards, meaning over centuries. As the basalt cooled, it contracted, and the contraction cracked the rock into columns. The geometry that emerged is hexagonal, columns with five or six sides in near-perfect arrays, some of them sixty feet tall.
This is not an artistic result. It is a physical one. When a uniform material cools and contracts from all directions equally, the most efficient geometry for the crack pattern that emerges is hexagonal. Hexagons are how a plane fills itself most efficiently with identical shapes, which is also why honeybees build hexagonal cells and why soap bubbles form hexagonal arrays. The basalt did what physics told it to do, and it produced what looks, to a human eye, like craftsmanship.
Ten thousand years ago, a glacier scraped across the top of the columns, shearing them flat. The tops of the posts, exposed where the glacier passed, look like a tile floor. If you walk up onto the top of the Postpile, you are walking on a surface that a glacier finished.
The columns are a National Monument. They are also a geometry lesson that happens to be ninety-five thousand years old.
