Dictionary
foot•wall
Pronunciation: (foot'wôl"), [key]—
n.
1. Mining.the top of the rock stratum underlying a vein or bed of ore. Cf.
hanging wall (def. 1).
2. Geol.a mass of rock lying beneath a fault plane.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.