Clay structure changes when it gets wet and dries out. The size of the spaces between clay particles is the main factor in these changes. Young soils get denser when they dry, while older soils become looser. Cracks in the soil depend on how much pressure is on it and how stressed it was to begin with. When soil dries, big holes increase, but when it gets wet, most big holes close up. After many wet and dry cycles, the soil's holes and properties stay more stable.