Traditional Scottish Farmhouse Gable wall Construction

When they built a house up here two hundred and fifty years ago, they didn't pussyfoot around with breeze-blocks and bricks: they found the largest boulders they could, and piled them up and stuck them together with lime mortar! A neighbouring farmhouse is having its gable end repointed at the moment, which has stripped and exposed the massive stonework involved.With the lime mortar removed, what is still holding it all together? Gravity!