rimrock

/ˈrɪmˌrɑk/
noun
  1. A steep cliff or rock face that forms the edge of a plateau or canyon, often found in dry, mountainous regions.
    • Ancient petroglyphs were discovered on the face of the rimrock.
    • The hikers stopped to admire the view from the rimrock overlooking the valley.
    • The ranch was nestled at the base of a towering rimrock.