18th April: Monument Valley

From Wd

from Dan's blog:

The geology of all parks throughout the trip was most interesting. In terms of variety and age, Grand Canyon stood out. However, Monument Valley, in the Navajo Nation, brought home the timescales involved in their formation because it has nearly disappeared.

Nearly, that is, on a geological timescale. But to all of recorded civilisation it has always looked pretty much the same, and it probably always will.

Fifty million years ago, layers of rock filled the entire area up to the top of the buttes you can see in the picture. Since then, water and wind carved out cracks in the rocks, over time cutting out more and more (depositing the debris mostly in California). Today, only a few sparse structures remain, and eventually they will disappear too. The remaining lumps have steep edges because the lower layers of rock are softer and undermine the upper layers only when the lower ones erode.

As an analogy, imagine waking up in the morning and seeing a blanket of snow. The sun comes out and by noon it has all disappeared. Perhaps at one minute to 12, there might just be a few isolated mounds of snow ready to melt away. The ‘monuments’ in the valley are those last remaining bits. We are stuck in this 11:59 moment through all of civilisation. Throughout humanity’s future, it is unlikely that a map of the monuments produced today will ever exist at a time when it becomes wildly inaccurate.