ted--Evidences of Ice-action During the
Tertiary Period--The Weight of the Negative Evidence--Temperate Climates in
the Arctic Regions--The Miocene Arctic Flora--Mild Arctic Climates of the
Cretaceous Period--Stratigraphical Evidence of Long-continued Mild Arctic
Conditions--The Causes of Mild Arctic Climates--Geographical Conditions
Favouring Mild Northern Climates in Tertiary Times--The Indian Ocean as a
Source of Heat in Tertiary Times--Condition of North America During the
Tertiary Period--Effect of High Excentricity on Warm Polar
Climates--Evidences as to Climate in the Secondary and Palaeozoic
Epochs--Warm Arctic Climates in Early Secondary and Palaeozoic
Times--Conclusions as to the Climates of Secondary and Tertiary
Periods--General View of Geological Climates as Dependent on the Physical
Features of the Earth's Surface--Estimate of the Comparative Effects of
Geographical and Physical Causes in Producing Changes of Climate.

_Pages_ 169-209

CHAPTER X

THE EARTH'S AGE, AND THE RATE OF DEVELOPMENT OF ANIMALS AND PLANTS

Various Estimates of Geological Time--Denudation and Deposition of Strata
as a Measure of Time--How to Estimate the Thickness of the Sedimentary
Rocks--How to Estimate the Average Rate of Deposition of the Sedimentary
Rocks--The Rate of Geological Change Probably Greater in very Remote
Times--Value of the Preceding Estimate of Geological Time--Organic
Modification Dependent on Change of Conditions--Geographical Mutations as a
Motive Power in Bringing about Organic Changes--Climatal Revolutions as an
Agent in Producing Organic Changes--Present Condition of the Earth One of
Exceptional Stability as Regards Climate--Date of Last Glacial Epoch and
its Bearing on the Measurement of Geological Time--Concluding Remarks

_Pages_ 210-237

{xv}

PART II

INSULAR FAUNAS AND FLORAS

CHAPTER XI

THE CLASSIFICATION OF ISLANDS

Importance of Islands in the Study of the Distribution of
Organisms--Classification of Islands with Reference to
Distribution--Continental Islands--Oceanic Islands

_Pages_ 241-245

CHAPTER XII

OCEANIC ISLANDS:--THE AZORES AND BERMUDA

_The Azores, or Western Islands_

Position and Physical Features--Chief Zoological Features of the
Azores--Birds--Origin of the Azorean Bird-fauna--Insects of the
Azores--Land-shells of the Azores--The Flora of the Azores--The Dispersal
of Seeds--Birds as seed-carriers--Facilities for Dispersal of Azorean
Plants--Important Deduction