Exfoliation is primarily caused by changes in which environmental factor?

Exfoliation is primarily caused by temperature changes, specifically the process of thermal expansion and contraction. When rocks are exposed to significant temperature variations, they expand during the heat of the day and contract at night when it cools down. This repeated cycle of expansion and contraction can cause the outer layers of the rock to weaken and ultimately peel away, a process often referred to as exfoliation. This phenomenon is particularly evident in granite formations, where layers can become detached due to these thermal stresses.

Other environmental factors, such as water content, pressure, and wind speed, can influence weathering processes but do not primarily drive the exfoliation process. Water might contribute to chemical weathering, pressure changes can lead to different types of physical weathering, and wind speed can enhance erosion, but none are the main forces behind the thermal expansion that leads to exfoliation.