Mud peeling & crack formation in drying clays

May be we all have seen that drying clay cracked into parts. It looks cool. But science beyond this is quite complicated but interesting.

Mud-cracking is a process commonly observed in hot, dry climates in regions where a clayey soil has been recently saturated with water such as intertidal regions or deserts after a rainfall. There are two main types of fractures that occur during drying.

The first type propagates perpendicular to the clay surface causing the soil to fracture into polygonal sections as in the first picture.

© utpal-biswas

The second type of fracture that occurs with the formation of shrinkage cracks is the formation of “mud curls” or mud peeling. In this case a “peeling” crack propagates parallel to the surface of the clay. Depending on the thickness of the peeled layer, the peel can roll up to leave a characteristic mud curl as in the pictures.

© utpal-biswas

REFERENCES:

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2010JF001842