A while back I started noticing occasional strange pavement patterns, which put me in mind of an old toy I once had, way back in the middle of the previous century:
Photoed by me earlier this week. I just did some Photoshop(clone)ping (contrast, sharpening) to make everything clearer, although it was pretty clear to start with.
I’m guessing these marks are made by a machine doing cleaning of some sort. I further guess that something has to be a bit wrong for this to happen. I particularly note how the pattern is in no way impeded by the joins of the pavement slabs, which suggests that quite a lot of power is being applied, by a quite heavy machine which cannot be easily deflected from the path it has been set on.