A canal excavated in the rock

At Coteau-du-Lac, a point formed by superimposed layers of dolomite containing lime and magnesium, the British military excavated a canal by removing rock layer by layer with iron wedges driven between the strata by sledgehammers. On large uncracked surfaces, they drilled holes and partially filled them with gunpowder to blast the rock, and winter frost likely also helped split the stone and ease the work. To prepare a blast, two men bored a hole with a jumper and sledgehammer, filled one-third of it with gunpowder, inserted a long needle, placed a small wad of straw above the powder, packed stone fragments into the hole, rammed the tamping with an iron rod, and sealed the top with moist clay. After the needle was removed, the opening was filled with fine powder or straws containing powder to act as a fuse, then the charge was lit before the explosion. Traces of the boring tools remain on the other side of the canal, where blasting holes in the bedrock measure from 3 to 4 cm in diameter and the deepest reach up to 60 cm into the rock.

Quebec · Canada