What forces lead to the formation of rift valleys?

Rift valleys form primarily due to tensional forces, which involve the pulling apart of tectonic plates. This process occurs at divergent boundaries where tectonic plates are moving away from each other. As the plates separate, the crust thins and stretches, leading to the formation of a valley-like depression. The tension causes the crust to break and create faults, resulting in the dropping of the land between these faults, which characterizes a rift valley.

Tensional forces are crucial in this process because they facilitate the extension and thinning of the lithosphere. In contrast, compressional forces would lead to the formation of features like mountain ranges rather than valleys, and shear forces, which involve lateral movement, could lead to strike-slip faults but not rift valleys. Frictional forces, while present in tectonic processes, are not the primary drivers behind the creation of rift valleys; rather, they play a role in how plates interact at boundaries.