Dimension stone (Salisbury area granites)
Mining (continued)

Slot drill at work drilling closely spaced vertical drill holes to separate five-foot-thick blocks of dimension stone.


These two images provide details of the slot drilling. The image to the left shows a track slot drill in the vertical position. It is drilling very closely spaced drill holes to separate five-foot-thick slabs. 

Before this step, a much larger block has been defined by horizontal and vertical slot drilling (bottom and back of the block), and jet channeling was used to burn the sides of the bench. 

The image below shows the diameter and spacing of the 20-foot-deep vertical drill holes that are bored to define the back side of a bench.

Closely spaced vertical 20-foot-deep drill holes define the back of the block to be quarried .