Volcanoes: What They are and What They Teach
9781465671233
213 pages
Library of Alexandria
Overview
In preparing this work, I have aimed at carrying out a design suggested to me by the late Mr. Poulett Scrope, the accomplishment of which has been unfortunately delayed, longer than I could have wished, by many pressing duties. Mr. Scrope's well-known works, 'Volcanoes' and 'The Geology and Extinct Volcanoes of Central France'—which passed through several editions in this country, and have been translated into the principal European languages—embody the results of much careful observation and acute reasoning upon the questions which the author made the study of his life. In the first of these works the phenomena of volcanic activity are described, and its causes discussed; in the second it is shown that much insight concerning these problems may be obtained by a study of the ruined and denuded relics of the volcanoes of former geological periods. The appearance of these works, in the years 1825 and 1827 respectively, did much to prepare the minds of the earlier cultivators of science for the reception of those doctrines of geological uniformity and continuity, which were shortly afterwards so ably advocated by Lyell in his 'Principles of Geology.' Since the date of the appearance of the last editions of Scrope's works, inquiry and speculation concerning the nature and origin of volcanoes have been alike active, and many of the problems which were discussed by him, now present themselves under aspects entirely new and different from those in which he was accustomed to regard them. No one was ever more ready to welcome original views or to submit to having long-cherished principles exposed to the ordeal of free criticism than was Scrope; and few men retained to so advanced an age the power of subjecting novel theories to the test of a rigorous comparison with ascertained facts. But this eminent geologist was not content with the devotion of his own time and energies to the advancement of his favourite science, for as increasing age and growing infirmities rendered travel and personal research impossible, he found a new source of pleasure in seeking out the younger workers in those fields of inquiry which he had so long and successfully cultivated, and in furthering their efforts by his judicious advice and kindly aid. Among the chosen disciples of this distinguished man, who will ever be regarded as one of the chief pioneers of geological thought, I had the good fortune to be numbered, and when he committed to me the task of preparing a popular exposition of the present condition of our knowledge on volcanoes, I felt that I had been greatly honoured. In order to keep the work within the prescribed limits, and to avoid unnecessary repetitions, I have confined myself to the examination of such selected examples of volcanoes as could be shown to be really typical of all the various classes which exist upon the globe; and I have endeavoured from the study of these to deduce those general laws which appear to govern volcanic action. But it has, at the same time, been my aim to approach the question from a somewhat new standpoint, and to give an account of those investigations which have in recent times thrown so much fresh light upon the whole problem. In this way I have been led to dwell at some length upon subjects which might not at first sight appear to be germane to the question under discussion;—such as the characters of lavas revealed to us by microscopic examination; the nature and movements of the liquids enclosed in the crystals of igneous rocks; the relations of minerals occurring in some volcanic products to those found in meteorites; the nature and origin of the remarkable iron-masses found at Ovifak in Greenland; and the indications which have been discovered of analogies between the composition and dynamics of our earth and those of other members of the family of worlds to which it belongs.
