Escarpment is related to escarp, an old military fortiﬁcation term for a slope or banked wall that lies at the foot of a rampart. In the nineteenth century, naturalists began using escarpment to mean a long line of cliffs, a continuous ridge, or a series of hills that because of faulting or erosion rises abruptly from a level or gently sloping plain or plateau. The dramatic and impregnable features of a cliff escarpment are on display in the three-hundred-mile-long, two-thousand-foot-high, yellow-to-gold-towhite limestone of the Mogollon Rim that forms the southern edge of the Colorado Plateau in Arizona. Less spectacular but perhaps more important is the Balcones Escarpment that cuts across central Texas, manifesting itself as a line of low hills. It divides Texas’s coastal plain from its western hill country and marks the boundary between the cattle-ranch culture of the American West and the traditional agrarian and farming culture of the American South and East.