I like dolerite. It is a solid rock which weathers to a rough pitted surface which is great for climbing. At the base of cliffs like these, it is ideal for seal and bird colonies. There isn't a lot to disturb them. Fishermen don't like the seals and may harrass them (illegal to do so) and there are tour boats which go around this coastline. Otherwise, the only disturbance is the rare mad climber.