Letter to Sir Archibald Geikie from Capt Clarence Edward Dutton. He encloses a report by Clarence King and explains the poor quality of his own entry in this. He discusses the formation of the basaltic plateaux which are cut by the Grand Canyon in the light of some articles written by Geikie. He concludes that there are 2 models of volcanic eruption: The Mediterranean Type where many small eruptions concentrated in a small area produce cinder cones and the Rocky Mountain Type where few very large eruptions diffuse over a large area.