CHAPTER I. CAUSE OF COLD AND MILD PERIODS. CHAPTER II. HOW ICE PERIODS IN THE NORTHERN HEMISPHERE ARE BROUGHT ABOUT. CHAPTER III. THE SPREAD OF GLACIERS DURING COLD EPOCHS. CHAPTER IV. THE GLACIERS OF THE TEMPERATE ZONES. CHAPTER V. REMARKS ON THEORIES ADVANCED FOR EXPLAINING ICE PERIODS. THIS MAP SHOWS THE SPREAD OF GLACIERS AND ICEBERGS, AND THE EXTENSION OF SOUTHERN LANDS DURING ICE AGE AND ALSO THE DIRECTION OF WINDS AND OCEAN CURRENTS. Map 2 THE |