harmless-depth theory

harmless-depth theory

[′härm·ləs ¦depth ‚thē·ə·rē]
(mining engineering)
Formerly, the hypothesis that there was a certain depth below which mining could be carried on without risk of damage to the surface.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.