Figure 27. Coming back to reality, I have labeled each of the Powder River sandbars with a number corresponding to its age relative to the others, in an attempt to see the timing of compressional faulting. There is, in general, an east-to-west progression, indicating that thrusting proceeded generally away from the missing thrust/mountain range on the west. Also, more late thrusts appear in the south than they do in the north. This somehow relates to regional tectonics, but I’m not sure how.