How do cracks appear in mud flats during the period of drought?

Cracks in mud flats







We have all seen the cracks crisscrossing all over the surfaces of mudflats. Ever wonder how they appear in a flat drought area? Let’s discuss in detail!

These cracks are called mud cracks or desiccation cracks. They are sedimentary structures. Although they are quite beautiful in their own way, one may wonder how they appeared in the first place.

When a mudflat dries up due to constant evaporation of water, the mud on the upper surface contracts. It sets up a uniform tension throughout the area, and as a result, a crack opens under this tension force. The material to either side is compressed perpendicular to the length of the crack. Gradually, as the squeezing builds up, the easiest way to relieve this pressure is for a new crack to open at right angles to the first one. Such rifts co-occur all over the perched flat and the result is an intricate pattern of polygons.

If the layer of mud is thin, the more rapid shrinking of the upper surface will cause the edges of the polygons to curve upward, and mud curls will appear. In a few cases, some of these cracks can be half a meter wide and double in depth. If emerging on a slope, these tubes of dried mud will simply roll away.

Mud cracks naturally appear in areas that were once saturated with water. Over time due to several reasons, the water dries out, resulting in dry sediment that leads to mud cracks. You will most probably find these cracks on abandoned river channels where the river has changed its direction of flow, floodplain muds that were once flooded, or dried ponds.