'The ridge upon which the companions stood went down steeply before their feet. Below it twenty fathoms or more, there was a wide and rugged shelf which ended suddenly in the brink of a sheer cliff: the East Wall of Rohan. So ended the Emyn muil, and the green plains of the Rohirrim stretched away before them to the edge of sight.'
JRR Tolkien: The Lord of the Rings
: The Two Towers: Book III
, Chapter 2: The Riders of Rohan