It must be borne in mind that we have no other methods of ascertaining the truth than by close observation, making diligent search, in order to discover what this earth's crust is made of. We have no supernatural facilities to give us information, and we are very certain there never were any. What information we are reckoned to have, handed down by our antiquated barbarian forefathers, is of a different nature. It refers--briefly stated--to the conduct of Man, the manner in which he shall act as an individual, or collectively as a community; including a great number of what are considered now theatrical or mountebank ceremonies, fancy customs, sacrifices, and a repetition of certain phrases, ordinarily called prayers, accompanied by illustrative images and pictures, and movements of body--fantastic symbols and devices created and prescribed by man. Having no other means of ascertaining facts, man was naturally compelled to search for testimony in the earth's crust--to discover what it is composed of; the kind of material; how it was formed; the time it took to form; the period that elapsed between formations; how the layers or strata were superposed one upon another; what substances were found in them; where organic life was first found; what it consisted of; when man first appeared. By examining this table we get a glimpse of the true state of things. This shows the order of superposition, or chronological succession, of the principal European groups: I. Post-Tertiary. A. Post-Pliocene. Periods and Groups. 1. Recent. Peat mosses, shell marls, with bones of land animals, human remains and works of art. Newer parts of modern deltas and coral reefs. 2. Post-Pliocene. Clay, marl, volcanic trap. All the shell of living specimens. No human remains or works of art. Bones of quadrupeds, partly of extinct species. II. Tertiary. B. Pliocene. 3. Newer Pliocene. Boulder formation. Cavern formation, or Pleistocene. Three-fourths of fossil shells of extinct species. A majority of the mammals extinct; but the genera corresponding with those now surviving in the same great geographical and zoological provinces. Icebergs frequent in the seas; glaciers on hills of moderate height. 4. Older Pliocene. A third or more of the species of mollusca extinct. Nearly, if not all, the mammalia extinct. C. Miocene. 5. Miocene. About two-thirds of the species of shells extinct. All the mammalia extinct. D. Eocene. } Fossil shells of the Eocene period, with very 6. Upper Eocene. } few exceptions, extinct. All the mammalia of } extinct species, and the greater part of them 7. Middle Eocene. } of extinct genera. Plants of Upper Eocene } indicating a south European or Mediterranean 8. Lower Eocene. } climate; those of Lower Eocene a tropical } climate. III. Secondary. E. Cretaceous--Upper. 9. Maestricht beds. Yellowish-white limestone. Large marine saurians, etc.