The range of physical geography found in Arizona is typical of the great contrasts in the state. There are mountains of all ages, shapes, and origins; there are high plateaus, and plateaus upon plateaus; and other areas are noted for broad, open valleys (Map 2. 1). This physical variety is accompanied by many climatic variations, with some portions of the state averaging less than 3 in. of precipitation a year, and other regions receiving 10 times that amount. The vegetation also varies greatly, ranging from barren deserts to forests.