Weathering in the Desert

May 08, 2019


Photographer: Thomas McGuire
Summary Author: Thomas McGuire 

If you think of weathering as a destructive process, it’s no wonder it gets a bad rap. But if you think of weathering as the adjustment of Earth materials to the conditions at Earth’s surface, weathering sounds more appealing. And it is.

Weathering is a function of two factors; rock type and climate. This remote desert in Eureka Valley of Death Valley National Park is usually very dry with daily temperatures that often vary by 60 degrees F (35 degrees C) in a single day. Brutally hot summers and sub-freezing winters are the norm here. The rock is mostly a mixture of basalt, granite and slate.

This image shows a variety of weathering (adjustment) mechanisms, clockwise from the left:

1.) Abrasion by wind-blown sand creates flat surfaces on partly buried rocks, creating a type of rock called ventifacts. (There are many good examples here.)

2.) This rock was split, possibly by daily expansion and contraction in the temperature extremes. Note more rusting (oxidation) on the older outer surface.

3.) The largest rock (the bowling ball) was probably tumbled and abraded round in a desert arroyo during monsoon storms before spalling (onion peel weathering) in the desert sun.

4.) This last rock shows that different minerals weather at different rates. The pits are left by the faster weathering minerals.

In my opinion, Death Valley is one of the most underrated of our National Parks. It’s also one of our least visited, large National Parks. When the word Death, is part of the title and when the highest temperature ever recorded in the western hemisphere was observed here, I suppose one shouldn’t wonder why. If you decide to visit Eureka Valley be prepared for a long drive (30 mi or 50 km) on rocky dirt roads. Photo taken in early April 2019.