The Thanksgiving Crust was 18-24" down from the road to our high point of 2300'. See below for two pits - one at 1900' and one at 2300' - which were dug to compare crust structure/faceting at two different elevations.
The crust was much thicker and buried less deep at 1900', with variation in crust thickness even along the brief distance of the 1 meter pit wall. Small facets (.5mm) surrounding the crust - above and below it at 1900' - didn't show a significant difference in layer hardness when compared to the rounds above and below. No results - even on overdrive - for CTs on the T-Day crust at 1900'.
At 2300' facets were only found below the top of the Thanksgiving Crust, which was 5mm thick and firmly bonded to the slab above it. At this location, the facets were larger (.5 - 1mm) and softer (fist+), in a 3cm thick layer that had very consistent structure across the pit wall. For propagation tests, I got a ECTN result only after "extreme" overdrive (~15 extra taps with lots of force) while a PST failed to the end after just a 30cm cut length. See below for full details!