year some new igneous rocks are produced in the bowels of the earth, but we cannot watch the progress of their formation; and as they are only present to our minds by the aid of reflection, it requires an effort both of the reason and the imagination to appreciate duly their importance.” But that they are actually of extreme importance, that in fact all the most characteristic features of our earth at present are due to the steady action of these two causes, no geologist now doubts. I propose now to consider one form in which the earth’s aqueous energies effect the disintegration and destruction of the land. The sea destroys the land slowly but surely, by beating upon its shores and by washing away the fragments shaken down from cliffs and rocks, or the more finely divided matter abstracted from softer strata. In this work the sea is sometimes assisted by the other form of aqueous energy—the action of rain. But in the main, the sea is the destructive agent by which shore-lines are changed. The other way in which water works the destruction of the land affects the interior of land regions, or only affects the shore-line by removing earthy matter from the interior of continents to the mouths of great rivers, whence perhaps the action of the sea may carry it away to form shoals and sandbanks. I refer to the direct and indirect effects of the downfall of rain. All these effects, without a single exception, tend to level the surface of the earth. The mountain torrent whose colour betrays the admixture of earthy fragments is carrying those fragments from a higher to a lower level. The river owes its colour in like manner to earth which it is carrying down to the sea level. The flood deposits in valleys matter which has been withdrawn from hill slopes. Rainfall, acts, however, in other ways, and sometimes still more effectively. The soaked slopes of great hills give way, and great landslips occur. In winter the water which has drenched the land freezes, in freezing expands, and then the earth crumbles and is ready to be carried away by fresh rains; or when dry, by the action even of the wind alone. Landslips, too, are brought about frequently in the way, which are even more remarkable than those which are caused by the unaided action of heavy rainfalls.