Wisemans Ferry, Sydney, NSW, Australia
The 'Devines Hill' section of the Great North Road, constructed 1829 - 1836 to replace the 'Finch's Line' section (Governor Ralph Darling deemed it too steep).
The horizontal holes are ‘wedge pits’ - a line of holes across the edges of a stone, into which an iron wedge was driven by a sledgehammer. The iron wedge was hit once or twice, moved to the next hole and struck again - and the entire operation repeated several times, until the rock began to give way.
The vertical hole is a remnant from the way several of the stone blocks were removed - using gunpowder. The hole itself was formed from convicts working in pairs, driving a ‘jumper bar’ into the rock with a sledgehammer. Gunpowder was then poured into the shaft, and most likely tamped down with clay.
AustraliaGreat North RoadNSWRalph DarlingSydneyWisemans Ferryblasting holewedge pits
From Great North Road