Third Rock for the Sand

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Decomposing Rock, Sand, and Landscape Evolution, Joshua Tree National Park, California

Decomposing Rock, Sand, and Landscape Evolution, Joshua Tree National Park, California

The Earth is often referred to as ‘the third rock from the Sun’.

WARNING: This post contains graphic images and explicit geologic explanations!

When the molten core of the Earth invades fractures in the overlying rock it forms seams or large bodies (batholiths) of new rock as it hardens. Because the cooling and hardening occur below the surface (rather than by violent ejection via a volcanic eruption)  the molten rock cools slowly and large crystals form. A variety of crystalline igneous rocks are formed. What type of rock depends on the composition of the molten material and the cooling rate.

These granitoid rocks weather into individual coarse crystal grains which we call sand.

In arid climates like the Mojave Desert in southern California these sands provide a difficult challenge for plants. The coarse grains don’t provide many nutrients.  The sand doesn’t hold very much water. It evaporates or drains quickly. There isn’t very much water to begin with.

Slowly as the sand continues to weather, nutrients and smaller particles are produced. The material retains more water and small plants can survive. Over time these nutrients and water support larger plants.

These three rocks in Joshua Tree National Park tell the rudimentary stories of landscape evolution and plant succession in an arid climate on granitoid rock formations.

The crumbled sand on the left shows small water channels. The sand has been carried by the water and deposited in a small alluvial fan deposit. Plants are starting to occupy deeper pockets of sand in the shade under the rocks. It is a micro model of the vast alluvial fan landforms that occur at the base of the mountains and ridges throughout the arid west of the U.S.

The three crumbling granitoid rocks are interesting shapes resting on an exposed larger bolder. The low-angle evening light highlights the granular makeup of the rock. That is what drew me to this spot initially. But as I looked at the photo I realized that it told a bigger story.

I got feedback on this photo during an art exhibit critique. The reviewer thought that I should have cropped off the left side of the photo up to the edge of the rock.

That might make sense for art composition or to have an abstract photo of three generic shapes. But I feel very strongly that photographs need context. I am not drawn to abstract snippets of scenes. Some people are and they succeed with photographs of splotches on pavement or smashed cans on the ground etc.

If I had cropped this photo the three rounded shapes could have been pottery or any other material, but just shapes. Most of the story of the formation of arid landforms and plant succession would have been lost. I call the photo ‘Making Sand’ and I had hoped that the name would call attention to the context of the three shapes. But maybe it was an obtuse name that nobody thought about.

It is another example of what harsh conditions plants can survive in. And by surviving there and contributing their organic matter remains they make it easier for the next plants. It is not abstract art but the meaning is probably still not apparent to most people. I try to combine artistic composition with context with a little intrigue to tell a story. I think that knowing where the story takes place enhances the image rather than detracts from the composition. It is a balancing act.

Until a person has an art reputation it is hard to get people to stop and look and think about what you are doing. These are just rocks on the ground, big deal.

There are more photos of the Mojave Desert in the Photo Gallery at my website:




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