[5] Penrhyn quarry in Bethesda was based around a single large pit over 400 feet deep, worked as a series of terraces.
A variety of means were used to transport slate from the terraces to the mills where the rock was processed.
The quarry already had an extensive internal narrow gauge railway system in place, and many terraces were connected via inclines.
Blondins were used to connect more remote terraces directly to the mills - they were distinguished by the fact that rock was transported on the ropeways in railway wagons slung from cradles.
Though most well-known in the Welsh slate industry, they were used in quarries of many sorts, and on bridge construction and other engineering projects.