Weather Words: Desiccation Cracks

Have you ever been in an area so drought-stricken that the ground appears more like a mosaic than a flat surface? Those are desiccation cracks. They are the polygon-shaped fractures that form in soil, mud or sediment as it dries out.

They usually appear after wet ground has been exposed to heat or dry air, causing the material to shrink. These cracks are commonly seen in dried-up lake beds, riverbanks, floodplains or after heavy rains recede. As the surface water evaporates, the soil contracts and fractures, creating a natural mosaic pattern that can range from tiny, hairline cracks to wide, gaping splits.

The shapes of desiccation cracks are often roughly polygonal, forming patterns that can look almost geometric. The exact size and shape depend on factors like soil composition, moisture content and how quickly the ground dries.

Desiccation cracks aren’t just visually interesting, they can also tell a story about the environment. Scientists can use them to study past weather conditions, soil health and even ancient landscapes preserved in the rock record. Fossilized desiccation cracks, called mudcracks, provide geologists clues about prehistoric lakes and climate patterns millions of years ago. Even in modern settings, these cracks influence water infiltration, plant growth and erosion patterns.

Jennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.