Take rain on a frigid day as it falls down and creeps into small cracks in between. As the night comes and the water freezes, forcing the rock apart from within, it splits like a seam under pressure. Weathering is slow, but no rock on Earth is hard enough to resist it.
Whethering, a word without fixed dictionary meaning, but what I understand as being inside the question, between two or more possibilities, before any of them settles.