CONTEXTS 



Formations ; the Origin of Chalk — Fresh-water and Shore- deposits as 

 Proving the Permanence of Continents — Oceanic Islands as Indications 

 of the Permanenee of Continents and Oceans — General Stability 

 of Continents with Constant Change of Form — Effect of Continental 

 Changes on the Distribution of Animals — Changed Distribution Proved 

 by the Extinct Animals of Different Epochs— Summary of Evidence 

 for the General Permanence of Continents and Oceans. Pages 83 — 105 



CHAPTER YII 



CHANGES OF CLIMATE WHICH HAVE INFLUENCED THE DISPERSAL OF 

 ORGANISMS : THE GLACIAL EPOCH 



Proofs of the Recent Occurrence of a Glacial Epoch — Moraines — Travelled 

 lilocks — Glacial Deposits of Scotland : the "Till" — Inferences from 

 the Glacial Phenomena of Scotland — Glacial Phenomena of North 

 America — Efiects of the Glacial Epoch on Animal Life — Wann and 

 Cold Periods — Palteontological Evidence of Alternate Cold and Warm 

 Periods — Evidence of Interglacial Warm Periods on the Continent and 

 in North America — Migrations and Extinctions of Orc;anisms Caused 

 by the Glacial Epoch >af/cs 106— 124 



CHAPTER VIII 



THE CAUSES OF GLACIAL EPOCHS 



Various Suggested Causes — Astronomical Causes of Changes of Climate — 

 Difference of Temperature Caused by Varying Distances of the Sun — 

 Properties of Air and Water, Snow and Ice, in Relation to Climate — 

 Effects of Snow on Climate — High Land and Great Moisture Essential 

 to the Initiation of a Glacial Epoch— Perpetual Snow nowhere Exists 

 on Lowlands — Conditions Determining the Presence or Absence of 

 Perpetual Snow — Efficiency of Astronomical causes in Producing 

 Glaciation — Action of Meteorological Causes in Intensifying Glaciation 

 — Summary of Causes of Glaciation — Effect of Clouds and Fog in 

 Cutting off the Sun's Heat — South Temperate Amer'ca as Illustrating 

 the Influence of Astronomical Causes on Climate — Geographical Changes 

 how far a Cause of Glaciation — Land Acting as a Barrier to Ocean- 

 cuiTents — The Theory of Interglacial Periods and their Probable 

 Character — Probable Effect of Winter in aphelion on the Climate of 

 Britain — The Essential Principle of Climatal Change Restated — 

 Probable Date of the Last Glacial Epoch— Changes of the Sea-level 

 Dependent on Glaciation — The Planet IMars as Bearing on the Theory 

 of Excentricity as a Cause of Glacial Epochs . . Pages 125 — 168 



