In the original work the chapter on Eruptive Rocks comes at the end of the work, but, as the work proceeded, so many unexplained allusions to that chapter were found that it seemed more logical, and more in accordance with chronological order, if the expression may be used, to place that chapter at the beginning. A new edition of the French work having appeared in the early part of 1866, to which the Author contributed a chapter on Metamorphic Rocks, a translation of it is appended to the chapter on Eruptive Rocks. A chapter on the Rhætic (or Penarth) beds has been inserted (amongst much other original matter), the stratigraphical importance of that series having been recognised since the publication of the First Edition. In the present Edition the text has been again thoroughly revised by Mr. Bristow, and many important additions made, the result of the recent investigations of himself and his colleagues of the Geological Survey. THE WORLD BEFORE THE DELUGE. GENERAL CONSIDERATIONS. The observer who glances over a rich and fertile plain, watered by rivers and streams which have, during a long series of ages, pursued the same uniform and tranquil course; the traveller who contemplates the walls and monuments of a great city, the first founding of which is lost in the night of ages, testifying, apparently, to the unchangeableness of things and places; the naturalist who examines a mountain or other locality, and finds the hills and valleys and other accidents of the soil in the very spot and condition in which they are described by history and tradition--none of these observers would at first suspect that any serious change had ever occurred to disturb the surface of the globe. Nevertheless, the earth has not always presented the calm aspect of stability which it now exhibits; it has had its convulsions, and its physical revolutions, whose story we are about to trace. The earth, like the body of an animal, is wasted, as the philosophical Hutton tells us, at the same time that it is repaired. It has a state of growth and augmentation; it has another state, which is that of diminution and decay: it is destroyed in one part to be renewed in another; and the operations by which the renewal is accomplished are as evident to the scientific eye as those by which it is destroyed. A thousand causes, aqueous, igneous, and atmospheric, are continually at work modifying the external form of the earth, wearing down the older portions of its surface, and reconstructing newer out of the older; so that in many parts of the world denudation has taken place to the extent of many thousand feet. Buried in the depths of the soil, for example, in one of those vast excavations which the intrepidity of the miner has dug in search of coal or other minerals, there are numerous phenomena which strike the mind of the inquirer, and carry their own conclusions with them. A striking increase of temperature in these subterranean places