Bob and I did a little subsurface investigation in Seattle for a foundation excavation. We had the advantage of a good project manager for the developer that noted that there was a good exposure of the subsurface within a deeper part of the foundation of the existing building on the site and came up with a scheme for excavating the foundation. Our job was to simply verify the soil types and develop the geometry of the excavation in a manner that would be safe for the workers and would not put the neighboring building and property at risk.
The area is mapped as glacial till and I had seen enough of the local till in that neighborhood to suggest we could likely reach undisturbed very hard till with hand tools. Saved a bit of money and time as indeed we had success. Hard glacial till may be lousy for gardens and stormwater drainage, but it does have some geotechnical advantages.
Bob measures and tests the hard unweathered glacial till in our first pit
The second pit found very hard till at less than 1.5 feet.
One last note: Happy Veteran's Day to Bob and all our veterans.