I'm not sure if the images are the same, but from being there, and as evidenced by the video it is clear that the original limestone wall was repaired using facing granite (ashlars). The original limestone wall has been cut back to accommodate the varying widths of the granite repair ashlars..
So therefore the question is why did they use repair, facing ashlars of various widths/depths??
Obviously the granite facing was not custom cut for the job . So therefore as a "work around" they cut the wall instead.
I'm of the opinion that the walls were refaced in dynastic times using re-cycled/found granite. Granite that could not readily be trimmed to size.
Dynastic salvage and restoration.
Look at the video at 5.43, behind him there's one of the ashlar rebates (cut outs)
There are many like that. Some still with repair ashlars in place.
Post Edited (28-Jun-15 18:50)