Fault block mountains are formed primarily through the tectonic forces that create tension and produce faulting in the Earth’s crust. These types of mountains are typically associated with divergent boundaries, where tectonic plates move apart, allowing blocks of the Earth’s crust to either uplift or drop due to the shifting forces.
In contrast, transform boundaries are locations where two tectonic plates slide past one another horizontally. The motion at these boundaries is primarily lateral, which means that the crust is not being pulled apart or compressed in the same way that occurs at divergent and convergent boundaries. Because the mechanism of formation is different, the characteristics of the landforms that emerge from transform boundaries differ as well.
At transform boundaries, the lateral movement tends to create features such as fault lines and shear zones rather than the vertical displacements necessary for fault block mountains. The earlier horizontal sliding can lead to the development of linear ridges or valleys but does not typically create the steep, blocky profiles associated with fault block mountains.
In summary, fault block mountains are uncommon at transform boundaries because the lateral motion of tectonic plates does not create the same conditions for uplift and dropping of crustal blocks that generate these types of mountains. Instead, transform boundaries are characterized by different landforms that result from the unique stress and strain associated with horizontal movement.