There's this from 2001 when a dig was started near the Wall of the Crow before some work started nearby:


Robbers and Granite workers
This spring we turned to the area off the east end of the Wall of the Crow, our operation WCE (Wall of the Crow East), and were surprised to find more gallery walls. The gallery system ran farther north than we had thought! We had to excavate through many layers of sand and stonedence of much more extensive stone working a thick deposit of granite dust (the by-product of pounding granite) mixed with sand and innumerable large chunks of red granite and dark diorite. Many workers must have toiled away here shaping and dressing granite blocks. The sandy granite dust covered the entire 10 x 10-meter area that Tobias exposed and was 85 centimeters to 1.30 meters thick.

Aeragram Vol 5 Number 1 2001

Jon