Still, it may be that neither of the coast ranges was the work of a single cold epoch; but the western range must necessarily have been the earliest deposit. Although the coast ranges differ from the Sierras in their make up, yet it does not disagree with the glacial origin of the former inferior mountains, from the fact that the ice-sheets, while moving their bulk westward, displaced the deposits of such bays, lakes, rivers, and marshes as lay abreast of the Sierra slopes. The advancing ice-sheets, thousands of feet in depth, moving from a lofty and steep incline, pressed and ploughed below the somewhat superficial cretaceous and alluvial strata which lay in their course. The disturbed strata, while forced along in confused heaps in front of the ice, were amassed in ridges sufficient to form the hills of the coast ranges. The bowlders found imbedded in several of the coast hills must have been moved by the ice from the Sierras on account of the coast ranges not having a rocky core of sufficient firmness to give shape to such bowlders. Moreover, the temperature of the Pacific waters would not be favorable for glaciers to form on the coast ranges, with the ice-sheets of the Sierras terminating at the foot-hills. The Sacramento and San Joaquin Valleys are now covered by recent river deposits. Therefore, the glacial drift which should be traced from the Sierras to the coast ranges is concealed. Yet the abraded appearance of exposed solid rocks at the base of the foot-hills, and also the scattered bowlders which gradually disappear beneath the diluvial deposits of the plains, indicate that the Sierra ice-sheets could not have ended at the foot-hills, but must have moved further westward, while gathering immense accumulations in their front, sufficient to form the coast hills, the débris thus amassed being able to arrest the further movement of the ice seaward. The coast ranges in several places have been subject to igneous action, which may have been brought about through heat generated from pressure exerted on the interior masses after the ice had melted away, the heat thus produced being sufficient to cause outbursts of lava, where the nature of the material favored combustion. The low plains, lakes, and bays which separate the Sierras from the coast hills are in a position similar to the shallow sounds which separate Nantucket, Martha’s Vineyard, and Long Island from the inferior slopes of the mountains of New England. Therefore, while agreeing with glacialists, who believe that great geological changes have been wrought by ice-sheets in Italy and New England, it appears to me that the ancient glaciers of the Sierra Nevada have accomplished more extensive work, owing to the Sierras being situated in a more favorable position to receive the humidity of the ocean.