The soil on our property is quite "loamy." Really it's like very fine river sand. There are also a few spots with natural springs. They discovered this while clearing the lot. It was HOT, HOT, HOT and there were spots that stayed muddy for days. At first the builder thought that we might just have some water pockets - water trapped in the sand because of the clay below - but when they didn't evaporate over time, he knew we had springs. Our friends a few hundred feet away confirmed this when they started telling stories about getting stuck in soft spots on their yard equipment.
For a firm foundation - something very, very important - it was decided that we needed to put some piers in. It's not going to have piers all the way around, just mostly on the East side. Our driveway will be (is) gravel to make the moisture issues less of a problem.
Boy oh boy, do those holes bring joy to my heart! It's so very exciting! I was out there doing a very quick happy dance when I snapped these pictures.
Here is yesterday (first two pics) with today following: