escarpment

noun

1. A steep descent or declivity; steep face or edge of a ridge; ground about a fortified place, cut away nearly vertically to prevent hostile approach.

   “After the canyons, the most remarkable features of the country are the long lines of cliffs. These are bold escarpments scores or hundreds of miles in length,—great geographic steps, often hundreds or thousands of feet in altitude, presenting steep faces of rock, often vertical.”

   “The railway winds down the face of the escarpment on a steady grade of 1.05 per cent, which is considerably better than the old route, up which trains took 2 hr. to struggle 15 miles, with two stops.”