Before deciding on the right kind of foundation, it's necessary to drive a spike into the soil and find out how hard it is. So a young man with a pile-driving/drilling machine with his trousers not on properly came by and drilled holes in each corner of the floor plan and one in the middle.
On many building sites apparently, you can drill down about 6 metres before you hit rock. In our case, rock was hit at about 4 metres, which is a good sort of sign. Since our land is a little scraping off a large mountain, this is not really surprising. Many people choose low lying land that is just accumulated silt.
However, although the ground in general was quite hard, there was a bit of a soft spot in a middle layer at one of the corners. So the hole company recommended that instead of a footing foundation (a kind of buried wall essentially), we have a slab foundation that will be resistant to sinking in one place. This will be a little more expensive, but we have budgeted for it.
This inspecting the ground was supposed to have been something of an event, and I was urged to make haste on the way, lest we arrive late and miss something. But as somebody who has spent a good deal of time inspecting the ground in one way or another, I knew that it's not something to get excited about. In fact, it can be quite a boring matter.