Arches form where wave erosion cuts an opening through a headland as a result of differential erosion. The formation of an arch is much more favorable when waves attack a headland from two different directions.
Images
Arch, Stack and Sea Cave Burchfield, B. Clark; Foster, Robert; Keller, Edward; Melhorn, Wilton; Brookins, Douglas; Mintz, Leigh; Thurman, Harold.
Physical Geology.
Charles E. Merrill Publishing Co., 1982.
