Chapter IX: The Glacial Period and Croll's Theory

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