Many indications of ice action are found in these islands; striated surfaces are to be seen on the cliffs in Eday and Westray, in Kirkwall Bay and on Stennie Hill in Eday; boulder clay, with marine shells, and with many boulders of rocks foreign to the islands (chalk, oolitic limestone, flint, &c.), which must have been brought up from the region of Moray Firth, rests upon the old strata in many places.