Answer: pegs, and patience. A lot of patience, although less than you’d think. The video below claims that the first split took about an hour:
Via Laughing Squid. I do not know that this is the method used in antiquity to split rocks – it’s clearly easier to do this with iron or steel tools than it would be other metals – but the principles are easy to grasp, and it would certainly work. Watching this was surprisingly engrossing, too. I feel that I am (very, very) slightly less ignorant about stone than I was before; I applaud the skill of the videographers.
It’s how our ancestors did Stonehenge – having split a lot of wood with a maul and wedges, I’m not surprised the same way works with rock. I liked the musicality of the hammer on the wedges in the rock.
Yeah, that was interesting. I kept expecting him to play a tune.