Inside the vault there was a lot of rubble stone, our collected stuff in storage, bits of tile, mortar. Beneath this there was clay, clay, clay. A test pit had been done in 2016 with only a clay pipe stem found. The The plans called for excavation to 400mm, about 16". We did not realize until we started how much higher the tower was from the house - about 18" higher! So the concept of having the same floor levels throughout house and tower had to be revised. When we dug down to the 400mm level in the center of the room it was found that the threshold and interior wall were not supported all the way down.
After conferring with David Sweetman and our engineer, it was decided to take down the floor to a shallower level, about 8" or 200mm below the Hobbit door threshold. We did not want to destabilize any walls and taking out the clay through the one tiny door was grueling work, hence the "Pit of Despair"! Each bucket of clay weighed about 30 lbs and we had to take out about 300 buckets! See more about archeology here.