Which process involves the freezing and expansion of water in rock cracks?

The process that involves the freezing and expansion of water in rock cracks is known as freeze-thaw action. This geological process occurs when water seeps into cracks in rocks. When temperatures drop, this water freezes and expands, exerting pressure on the surrounding rock. As the ice thaws and the water melts, it causes the material to contract. Repeated cycles of freezing and thawing can gradually lead to the widening of the cracks and the eventual breakdown of the rock. Over time, this mechanism can lead to significant weathering of rock surfaces, contributing to the formation of features such as talus slopes or scree.

The other processes listed, while related to geological change, do not involve freezing and expansion in the same manner. Hydrolysis refers to the chemical reaction between water and minerals, leading to the alteration of the mineral structure. Carbonation is a process where carbon dioxide dissolves in water, forming carbonic acid, which can react with minerals in rocks. Exfoliation involves the peeling away of layers from the surface of rocks due to temperature changes, rather than the physical action of freezing water. Therefore, freeze-thaw action is particularly distinctive for its role in physical weathering through the mechanics of ice formation.