Anyone accustomed to the peculiar outlines which ancient ice action has produced in the Alps, cannot fail to be struck, at the first glance, by the contours to the upper parts of the Great Ormeshead and of the Carboniferous Limestone range which extends from near the village of Rhos to the Little Ormeshead; and a more minute examination only strengthens the conviction that, while the leading outlines of the hills are due somewhat to upheaval, but mainly to denudation—probably marine, the surface of the higher ground has in many cases been affected by ice.