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

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