Read it through once

On the way back to Stawell we had a chance to see a group of boulders called the Three Sisters—a curiosity oddly located; for it was upon high ground, with the land sloping away from it, and no height above it from whence the boulders could have rolled down. Relics of an early ice-drift, perhaps. They are noble boulders. One of them has the size and smoothness and plump sphericity of a balloon of the biggest pattern.