Sorry I didn't reply before, but I am surprised at the spread of the bits. I know we don't have a scale for them but it looks quite forceful and I can imagine flakes jumping off the surface due to stresses. However what I notice most is the ground colour which is dark around, and yet these objects are lying in a pale field that follows their pattern of deposition. Is it a light trick or what is it ?
Edit. And spalling is not confined to the hot sunside but at the top- all around. However it is a smaller boulder, and perhaps there is an understandable process going on here. Needs some other feedback from you Geo people. I can "sort of see it" but haven't got clarity yet.