VII.—The Cause of Crateriform Sand Dunes and Cwms

Extract

At St. Anne's-on-the-Sea, Lancashire, there are a great number of very large sand-hills. They are for the most part crateriform in the centre, from the gyratory movement of the wind in stormy weather. There must be some cause, however, which determines the course of the wind, for its natural action one would suppose should be to carry away dunes by sweeping them before it.