This is a more severe example of eroding hummocks and hollows.
Isolated haggs (islands) are now cut off from each other by groughs (small water channels) or even large pools!
Pools form where peat has washed down the hagg sides. They are so wet they are often completely bare of vegetation as few species can tolerate such wet, anaerobic conditions.
Cotton grass (Eriophorum spp.) which is tolerant to very wet conditions, is often found in very wet peaty pools.