Columnar Basalt - Palm Desert EarthCache

Welcome to Palm Desert

While visiting the area for Coachella, I noticed this striking fountain installation at The Village at University Park in Palm Desert, featuring vertical basalt columns. This EarthCache invites you to explore the characteristics of columnar basalt and how natural processes and human design interact in this display.

The Formation of Columnar Basalt

Basalt forms when lava from volcanic eruptions cools and solidifies into rock. If the lava cools slowly and evenly, it contracts as it loses heat. This contraction creates a network of fractures that typically form geometric patterns, often hexagonal, though other polygonal shapes can appear. These patterns result from the stress in the cooling rock being released evenly, which naturally divides the lava into columns. The cracks usually start at the surface and propagate downward, creating long, vertical structures. The slower and more uniform the cooling, the more regular the columns tend to be, while rapid or uneven cooling can produce irregular shapes.

As the columns grow, the tops may develop uneven surfaces or fractures depending on several factors. Natural weathering from wind, water, and temperature changes can chip or break column tops over time. Additionally, human handling during quarrying, cutting, and installation can modify their appearance, leaving edges jagged or surfaces polished. These factors combined mean that while the overall column shape reflects natural cooling and fracturing, details such as cracks, chips, or irregular tops often tell a story of both geological and human influence.

The toughness of basalt makes it a highly durable rock, able to resist erosion better than many other igneous rocks. This durability is why basalt columns are often preserved in natural settings or used in architecture and art. Even with its strength, water and weathering can slowly alter the surfaces, creating darker areas where moisture collects or lighter, rougher areas where it dries. Observing these variations provides insight into the original lava flow as well as the environmental and human forces that have shaped it since it was formed.

Geological Significance

Columnar basalt provides insights into cooling rates, volcanic environments, and fracture mechanics. While the columns here were clearly arranged and modified by human hands, their size, shape, and textures still reveal information about the original lava flow and cooling process. Basalt columns are used worldwide in architecture and art, from natural landmarks like Devil’s Postpile to urban installations such as this fountain.

Tasks for This EarthCache

To log this EarthCache, visit the site and complete the following tasks. Send me your answers via Geocaching or email.

1. Include "Columnar Basalt - Palm Desert - GCB5M2X" on the first line of your message.

2. Observe several basalt columns and determine how many sides each column has. Are most of the columns six sided, or do you see a variety of shapes? What does this tell you about the cooling conditions of the lava?

3. Some column tops are glossy and fractured. Are the cracks concentrated in certain areas, such as the center or edges? What might have caused these patterns of breakage?

4. Observe the basalt columns where water from the fountain flows and compare them to areas that stay mostly dry. What differences do you notice in color, surface appearance, or texture? What might be causing these differences?

5. In your log, attach a photo of yourself or a personal belonging with the basalt columns in the background. (Note: photos predating the publication of this EarthCache are not accepted.)