I have hitherto assumed a certain acquaintance, upon the part of the general reader, with the terms Eocene, Miocene, and Pliocene, happily invented by Sir Charles Lyell to designate three of the four great divisions of the Tertiary age. These, from their universal acceptation and constant use, have "become familiar in our mouths as household words." But it will be well, before further elaborating points in the history of these groups, bearing upon our argument, to take into consideration their subdivisions, and the equivalent or contemporary deposits composing them in various countries. This can be most conveniently done by displaying these, in descending order, in a tabular form, which I accordingly annex below. This is the more desirable as there are few departments in geological science which have received more attention than this; or in which greater returns, in the shape of important and interesting discoveries relative to man's existence, have been made. Comparatively recent--comparatively, that is to say, with regard to the vast æons that preceded them, but extending back over enormous spaces of time when contrasted with the limited duration of written history,--they embrace the period during which the mainly existing distribution of land and ocean has obtained, and the present forms of life have appeared by evolution from preceding species, or, as some few still maintain, by separate and special creation. THE TERTIARY OR CAINOZOIC AGE. | | | | | | 1. Recent } | | | } | |Man's | 2. Post Glacial } | |range |Man's } Post } |Man's |according |range, 3. Pleistocene or}Tertiary} |range, |to |generally Quaternary } } |according |Capellini,|admitted (including } } |to l'Abbé |Marsh, | Glacial } } |Bourgeois, |and | formation) } } |Quatrefages,|others. | } |and | 4. Newer Pliocene} } |others. | }Pliocene}Tertiary | +--------------------- 5. Older Pliocene} }or | }Cainozoic | 6. Upper Miocene } } | }Miocene } +---------------------------------- 7. Lower Miocene } } } 8. Upper Eocene } } } } 9. Middle do. }Eocene } } 10. Lower do. }