Which weathering process is primarily caused by rapid changes in temperature leading to mechanical breakdown of rocks?

The weathering process that is primarily caused by rapid changes in temperature leading to the mechanical breakdown of rocks is known as expansion and contraction. This process involves the repeated heating and cooling of rock material, which causes the minerals within the rock to expand when heated and contract when cooled. Over time, these continuous cycles of expansion and contraction create stress within the rock, leading to the development of fractures and, eventually, the mechanical breakdown of the rock itself.

In contrast, chemical weathering involves the alteration of the chemical composition of rocks and minerals due to chemical reactions, often facilitated by water and atmospheric gases. Frost heaving specifically relates to the freezing and thawing of water in soil, causing soil particles to move upwards, while exfoliation refers to the peeling away of layers from the surface of a rock, typically influenced by temperature changes but in a manner that is more focused on the release of pressure rather than the mechanical breakdown caused by expansion and contraction. Thus, the correct choice accurately represents the weathering process associated with rapid temperature changes and mechanical rock breakdown.