escarpment

noun1

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.

   • 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. — 1950