Thanks to Rick Lloyd for a recent inquiry from another corner of the world:

Q: “...Once again I am making enquiries about crushed stone bases.  I've just run a drystone walling weekend here, the first ever in Japan.  The whole thing was a great success, in that I managed to get people to understand the science behind drystone walls, got them to build some drystone walling, had fun and more importantly for me managed to pass on the joy and beauty of drystone walling to a nation that has forgotten the grace and beauty of the natural world. Anyway the reason I am writing to you again is because one of the people attending the event said they live at an altitude of 1150m and in the winter the ground freezes to a depth of 60cm.  In such an environment is it necessary or advisable to dig the crushed stone base deeper than the frost or simply stick to the "half the height of the wall" calculation?”

A: “Congratulations on the successful walling weekend!  It's always gratifying to introduce others to the enjoyment we get from dry stone. At 1150 meters I'm guessing their soil depth is pretty thin; not that far to bedrock. If that's the case, then there may not be much excavation necessary, or even possible. For walls less than 1 meter high I think the "half the height" calculation is fine in any environment. For higher walls, especially retaining walls, in areas with a deep frost line I would recommend a footing that is at or below that depth. All best, Dan.”

Pictured above - photos from the workshop. Photo credit: Rick Lloyd.