There are two opposing theories about mountain formation and climate over the past 40 million years: either the surge of mountain building (i)_____ the global cooling or vice versa. The first of these two theories asserts that widespread mountain building cooled the earth as a result of the (ii)_____ mountains and climate. For example, mountain glaciers tend to be (iii)_____: once established, they increase the reflectivity of the surface, thus lowering temperatures and allowing more ice to form.