Haematites of great commercial importance occur in West Cumberland, chiefly in the Carboniferous Limestone. Worked as early as the twelfth century the annual output reached half a million tons by 1861, since when the output has varied between that figure and one million tons. During these years of active exploitation many ore-bodies in the exposed ore field were worked out and active exploration is now concentrated around and to the south of Egremont, where the Carboniferous Limestone plunges beneath the New Red rocks. Among the problems confronting the searchers for new ore-bodies in this concealed ore field there is one of long standing, upon which unanimity has not been reached, namely the origin of the haematites. The question of origin is not one of mere academic interest. Its solution affords an important clue in the search for new ore-bodies. Two theories—magmatic origin and deposition from meteoric waters—are and have been propounded by rival advocates during the last fifty years. J. D. Kendall (1893) attributed the origin of the ores to ascent of magmatic solutions in pre-Permian times. To him we owe the theory of metasomatic replacement of the limestone by haematite, now generally accepted.