A thrust fault is a type of planar fault where movement occurs horizontally, resulting in one slab of rock moving up and over a younger or underlying slab. This type of faulting is characteristic of compressional tectonic environments, where immense lateral forces push rock masses together. As plates or crustal segments converge, the frictional resistance causes the overlying material to shorten and deform, ultimately leading to the systematic upward transport along the fault plane. The forces involved are responsible for forming characteristic geological folds and complex mountain building structures by stacking rock layers upon one another.