I found this amazing picture on the Internet a while ago and have finally been to investigate. Here is a view looking down the slope. When I was there it was clear that I was looking down lines of stones.
I first read about solifluction a couple of years ago. It is when water in the ground freezes and expands, thus pushing stones upwards. This tends to push stones out of the way. The grit that is left can accommodate more water so this amplifies the frost-heave effect there and pushes more stones. The areas where the stones accumulate have less water to freeze so the stones stay put. I have seen pictures of it producing hexagons on flat surfaces but stripes on slopes. It has been suggested that melt water flowing down the grooves between the stone stripes extenuates the effect.
This picture shows solifluction producing hexagon-like shapes on the flat surface but them breaking down to become stripes on the slopes.
