Of course that method of grubbing out forest and burning stumps and gathering rock into piles, then capping it is a mainstay of GC construction since such has been done. But, I've seen these efforts to bury the grubbed out material and rock piles, capped, that have gone badly over seasons of winter freeze-thaw upheavals here in the norther states. I've seens caved in areas where the remaining stumps not consumed by enough fire have rotted and gave way, and boulder rocks poke upwards, and even irrigation placed over such buried material and it being broken during the upheavals.
For Tom D., or other GC constructor experts, what is the secret of keeping the boulders and large unburned stumps from heaving up through the surface turf eventually after seasons of winter frozen then thawed ground? Does anyone know if that upheaval of material issue was a specific problem here on Thompson's encredibly enchanting hole?