Causes of Glacial Periods--Actual Conditions of existing Glacial Regions--High Land in High Latitudes--Cold alone insufficient--Large Evaporation required--Formation of Glaciers--They flow like Rivers--Icebergs--Greenland and Antarctic Circle--Geographical and Cosmic Causes--Cooling of Earth and Sun, Cold Spaces in Space, and Change in Earth's Axis, reviewed and rejected--Precession alone insufficient--Unless with High Eccentricity--Geographical Causes, Elevation of Land--Aërial and Oceanic Currents--Gulf Stream and Trade Winds--Evidence for greater Elevation of Land in America, Europe, and Asia--Depression--Warmer Tertiary Climates--Alps and Himalayas--Wallace's _Island Life_--Lyell--Croll's Theory--Sir R. Ball--Former Glacial Periods--Correspondence with Croll's Theory--Length of the different Phases--Summary--Croll's Theory a Secondary Cause--Conclusions as to Man's Antiquity 293 CHAPTER X. QUATERNARY MAN. No longer doubted--Men not only existed, but in numbers and widely spread--Palæolithic Implements of similar Type found everywhere--Progress shown--Tests of Antiquity--Position of Strata--Fauna--Oldest Types--Mixed Northern and Southern Species--Reindeer Period--Correspondence of Human Remains with these Three Periods--Advance of Civilization--Clothing and Barbed Arrows--Drawing and Sculpture--Passage into Neolithic and Recent Periods--Corresponding Progress of Physical Man--Distinct Races--How tested--Tests applied to Historical, Neolithic, and Palæolithic Man--Long Heads and Broad Heads--Aryan Controversy--Primitive European Types--Canon Taylor--Huxley--Preservation of Human Remains depends mainly on Burials--About forty Skulls and Skeletons known from Quaternary Times--Summary of Results--Quatrefages and Hamy--Races of Canstadt--Cro-Magnon--Furfooz--Truchere--Skeletons of Neanderthal and Spy--Canstadt Type oldest--Cro-Magnon Type next--Skeleton of Cro-Magnon--Broad-headed and Short Race resembling Lapps--American Type--No Evidence from Asia, Africa, India, Polynesia, and Australia--Negroes, Negrillos, and Negritos--Summary of Results 317 CHAPTER XI. TERTIARY MAN.