1. The abnormal character of much of the fossiliferous deposits. 2. A radical and world-wide change of climate. 3. The marked degeneration in passing from the fossil world to the modern one. 4. The fact that the human race, to say nothing of a vast number of living species of plants and animals, has participated in some of the greatest of the geological changes--we really know not how to limit the number or character of these changes. Surely a true spirit of scientific investigation would now begin to inquire, =How did these changes take place?= Discarding the use of stronger language, it is at least utterly unscientific to begin somewhere at the vanishing point of a past eternity and formulate our pretty theories as to how this deposit was made, and how that was laid down, and the exact order in which they all occurred; while these "recent" deposits, in which our race and the plants and animals living about us are acknowledged to be concerned, are left over till the last, and we then find that they admit of absolutely no explanation. We ourselves, to say nothing of thousands of living species of plants and animals, have participated in some of the very greatest of the geological changes--we know not how many or how great. =These things must be first explained.= Has anything happened to our world that will explain them? Are there known forces and changes now in operation which, granting time enough, will amply and sufficiently explain these facts, as simply one in kind with those of the present day? To this last question we must admit that our historic experience, prolonged over several thousand years, utters a thundering =NO!= Volcanoes are every now and then breaking forth; but volcanoes and mountain ranges have nothing in common with one another as to structure and origin. No one claims that a single mountain flexure is now being formed or has been formed within the historic period. There are indeed "creeps" in the rocks in certain places, but these are not such as to contribute to the height of the mountains in which they occur, but rather the reverse. Sudden changes of level within small areas have occurred, but neither in extent nor in kind do they furnish any key as to past changes of level; while the so-called "secular" changes are so microscopic in extent and so doubtful in character that they are utterly unworthy of consideration in view of the stupendous problems which we are trying to explain. The well-known work of Eduard Suess is a standing protest that such geological chances are =not now in progress=; for, in speaking of how the land and ocean have exchanged places in the past, Zittel represents him as teaching that their "cause of origin until now =has not yet been discovered=."[94] Or, to quote the expressive words of Suess himself, with which he concludes his discussion of this very subject: