I. ˈ ̷ ̷ˌ ̷ ̷ noun
Etymology: rim (I) + rock
1. : a top stratum or overlying strata of resistant rock of a plateau outcropping to form a more or less vertical face (as in the wall of a canyon)
mesas topped with rimrock — Agnes M. Cleaveland
— compare cap I 2a(3)
2. : the edge or face of an outcropping of rimrock
stopping the car on the high rimrock , we looked down — Frank Waters
a high flat mesa, with rimrocks all around — Will James
II. transitive verb
West : to destroy (as a flock of sheep) by driving over a cliff