The district of Cleveland, long known for the beauty and variety of its scenery, has during the past few years acquired great importance through the discovery of valuable beds of iron ore in the Middle Lias. So much has been written on this district, and in a lesser degree on East Yorkshire generally, that the geological structure of this country must be tolerably well known. My object then is not so much to describe the beds as to give some notes on the physical geography of the country, explaining the relation of its present surface outlines to its internal structure, and to enquire by what means those external features have been produced.