The various elements of a landscape appear to the ordinary eye so simple, so obviously related to each other, and often so clearly and sharply defined, that they are not unnaturally regarded as the effects of some one general operation that acted for their special production; and where they include abrupt features, such as a ravine or a precipice, they are still popularly believed to be in the main the work of some sudden potent force, such as an earthquake or volcanic explosion. There is a general and perfectly intelligible unwillingness to allow that scenery which now appears so complete and connected in all its parts was not the result of one probably sudden or violent cause. Yet the simplest explanation is not always necessarily the correct one. In reality, the problems presented to us by the existing topography of the land, fascinating though they are, become daily more complex, and demand the whole resources of geological science. They cannot be solved by any rough-and-ready process. They involve not only an acquaintance with the recent operations of Nature, but an extensive research into the history of former geological periods. The surface of every country is like a palimpsest which has been written over again and again in different centuries. How it has come to be what it is cannot be told without much patient effort. But every effort that brings us better acquainted with the story of the ground beneath our feet, and at the same time gives an added zest to our enjoyment of the scenery at the surface, is surely worthy to be made.