In speaking or writing of the earliest stages of the world's history we have to adopt what seems to be the most likely history, modestly qualifying what we say by adding that these speculations are only the fruits of an inquiry that man has pushed beyond the ascertained facts. But we are on firmer footing when we come to deal with that portion of the globe which we can examine. The crust of the earth has been found to consist of successive layers of rock which, though far from constant in their occurrence, and though often broken and crumpled by subsequent disturbances, have been recognised over a large portion of the globe. They are the earth's own chronicle of its history. Had these rocks of the Geological Record remained in their original positions we should have known little of them, because only the most recent would have been visible. Owing, however, to the way in which the earth's crust has been twisted and cracked and broken, portions of the bottom layers have been pushed up to the surface, and the lower rocks have been inclined so that we can examine their upturned edges. Instead, therefore, of being restricted to examining a few hundred feet of earth crust we can examine many thousand feet. The total thickness of the rocks of Europe which contain fossil remains has been estimated at 75,000 feet, or fourteen miles. This vast depth of rock has been laid open to our observation by disturbances, twists, contortions, upsettings of the crust. We shall not press on the reader in a volume of this kind any detailed classification of the strata, but he will like to know the names of the five great periods into which geologic time is divided. The first period was the Archæan, embracing the periods of the earliest rocks wherein few or no traces of life occur. The second period was the Palæozoic (ancient life) or Primary, which includes the long succession of ages during which the earliest types of life existed. The third period was the Mesozoic (middle life), comprising a series of ages when more advanced types of life flourished. The fourth period was the Cainozoic (recent life) or Tertiary period, when such types of life as we know and see now appeared. This period, however, does not include man. The fifth period is the Quaternary or Post-Tertiary and Recent, and includes the time since man appeared on the earth.