BOOK III REPRINTS, SPECULATIONS, AND CHAPTER XX DENUDATION OF THE TWO AMERICAS1 'Whence it appears, not only that in proportion as knowledge becomes quantitative do its previsions become complete as well as certain, but that until its assumption of a quantitative character it is necessarily confined to the most elementary relations.'- Herbert Spencer's Essays, vol. i. Essay iii. INTRODUCTION WHEN, in 1876, I had the honour to deliver a Presidential Address to this Society, I chose as its subject-matter 'Geological Time.' I then had the pleasure to lay before you some calculations relating to 'Chemical Denudation,' which at the time possessed some little novelty. Since the information. was published it has, to a certain extent, been incorporated with geological literature. The subject was, however, far from being exhausted, nor is it likely to be for many years yet to In the meantime, having accumulated additional facts, it will be part of the object of this address to arrange and analyse them, so as to check the original generalisations, and further to illustrate the value in geological speculation of an accurate knowledge of the relative magnitude of the various objects and things dealt with. come. The importance of a quantitative examination of geological data is not yet properly appreciated. Some of our authorities, 1 Presidential Address to the Liverpool Geological Society, Session 1884-5. |