Honeycombing at Mount Rushmore

Dynamite was used until only three to six inches of rock was left to remove to get to the final carving surface. At this point, the drillers and assistant carvers would drill holes into the granite very close together. This was called honeycombing. The closely drilled holes would weaken the granite so it could be removed often by hand

See full article at http://web.archive.org/web/20080801031839/http://www.nps.gov/archive/moru/park_history/carving_hist/workers.htm