The POST-TERTIARY or QUATERNARY division comprises the concluding chapters of geological history. The _Pleistocene_ (_pleistos_, most, and _kainos_, recent) contains no extinct species of shells, but a number of extinct mammalia. In the _Recent_ deposits all the species of animals and plants are living. The Tertiary and Quaternary formations are partly of marine and partly of terrestrial and fresh-water origin. At the close of the Tertiary period the 'glacial epoch' of Pleistocene times began, and the British Islands and a large part of northern Europe and North America were then cased in snow and ice. Traces of glacial conditions have also been met with in the Eocene and Miocene. The evidence furnished by Palæozoic and Mesozoic formations points chiefly to mild, genial, and sometimes tropical conditions. But traces of ice action are occasionally noted (namely, in the Silurian, Old Red Sandstone, Carboniferous, Permian, and Cretaceous formations), pointing, perhaps, in some of the cases, to former alternations of cold and warm periods. Indeed, the belief is now gaining ground, that the so-called glacial epoch of Pleistocene times was not one long continuous age of ice, but rather consisted of an alternation of warm and cold periods. And it is not improbable, but highly likely, that similar alternations of climate have happened during every period of great eccentricity of the earth's orbit. QUESTIONS. Section 1. What is Geology? 2. Define the term _rock_. How many classes of rock are there? 3, 4, 5. Into what groups are the mechanically formed rocks divided? Define the terms _conglomerate_, _sandstone_, and _shale_. 6. What is the nature of the rocks belonging to the Aërial or Eolian group? 7. Give an example of a chemically formed rock. 8. Give examples of organically derived rocks. 9. What kinds of rocks are embraced by the Metamorphic class? 10. What are igneous rocks? 12. What is the mineralogical composition of granite? 13. What is meant by a _mineral_? 14. Name five minerals which do not contain oxygen. Where does _fluor-spar_ occur? What is the element that enters most largely into the composition of the earth's crust? 15. Name the forms under which the mineral _quartz_ occurs. Name some of the oxides of iron. What is _iron pyrites_? 16. Name two _sulphates_. Name two _carbonates_. Name some of the _silicates_. In what kinds of rock is _augite_ found? Where does it never occur? In what kinds of rock does _hornblende_ usually occur? Mention three species of felspar. What is one of the most distinguishing characteristics of mica? Name three silicates of magnesia. Mention some of their distinguishing peculiarities. Where do _zeolites_ commonly occur? 17. What is a _quartzose conglomerate_? What is a _calcareous conglomerate_? 18. What is _grit_? What is _freestone_? To what are the various colours of sandstone due? What is _shale_? 19. Name some typical Eolian rocks, and tell where they occur.