Iron-rich solutions precipitated the iron on to a syenite porphyry footwall. These are known as "footwall shortcuts". The UG2 chromitites are underlain by pyroxenite footwall that is distinct from hanging wall pyroxenite. In a normal fault, the hanging wall moves downward, relative to the footwall. The two sides of a non-vertical fault are known as the "hanging wall" and "footwall". The hanging wall occurs above the fault plane and the footwall occurs below it. The Mons Cupri rhyolite is in the footwall and shows typical silica-chlorite alteration. The deposits are found within the footwall and hanging wall of the St. Louis fault. In reverse, or thrust, faults, relative subsidence may be measured in the footwall. Thrust faults typically form ramps, flats and fault-bend (hanging wall and footwall) folds. The footwall is also much more extensively hydrothermally altered than in continental settings.