foreshaft sinking

foreshaft sinking

[′fȯr‚shaft ‚siŋk·iŋ]
(mining engineering)
The first 150 feet (46 meters) of shaft sinking from the surface; the plant and services for the main shaft are installed during this step.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.