What is the definition of stress in geological terms?

Stress in geological terms refers specifically to the force applied per unit area on a material, such as rocks. This definition highlights how stress is a measure of the intensity of internal forces acting within an object or a body of rock. When external forces are applied to a geological material, they lead to stress, which can result in changes to the material's shape or volume.

This concept is crucial for understanding various geological processes, such as the deformation of rocks during tectonic activity. It is essential to grasp that stress is not merely about the force itself but also how that force is distributed over an area, which can greatly influence rock behavior, such as causing bending, breaking, or flowing.

The other terms mentioned, such as the change in shape of a material or the amount of strain, relate to the effects of stress on materials rather than defining what stress itself is. Thus, while they are important in the broader context of understanding geological mechanics, they do not capture the specific definition of stress as it pertains to force distribution.