Geological Observations on the Volcanic Islands by Charles Darwin Contents EDITORIAL NOTE DETAILED TABLE OF CONTENTS CRITICAL INTRODUCTION CHAPTER I.—ST. JAGO, IN THE CAPE DE VERDE ARCHIPELAGO CHAPTER II.—FERNANDO NORONHA; TERCEIRA; TAHITI, ETC CHAPTER III.—ASCENSION CHAPTER IV.—ST. HELENA CHAPTER V.—GALAPAGOS ARCHIPELAGO CHAPTER VI.—TRACHYTE AND BASALT.—DISTRIBUTION OF VOLCANIC ISLES CHAPTER VII.—AUSTRALIA; NEW ZEALAND; CAPE OF GOOD HOPE INDEX TO VOLCANIC ISLANDS EDITORIAL NOTE Although in some respects more technical in their subjects and style than Darwin’s “Journal,” the books here reprinted will never lose their value and interest for the originality of the observations they contain. Many parts of them are admirably adapted for giving an insight into problems regarding the structure and changes of the earth’s surface, and in fact they form a charming introduction to physical geology and physiography in their application to special domains. The books themselves cannot be obtained for many times the price of the present volume, and both the general reader, who desires to know more of Darwin’s work, and the student of geology, who naturally wishes to know how a master mind reasoned on most important geological subjects, will be glad of the opportunity of possessing them in a convenient and cheap form. The three introductions, which my friend Professor Judd has kindly furnished, give critical and historical information which makes this edition of special value. G.T.B. VOLCANIC ISLANDS. DETAILED TABLE OF CONTENTS I.—ST. JAGO, IN THE CAPE DE VERDE ARCHIPELAGO. Rocks of the lowest series.—A calcareous sedimentary deposit, with recent shells, altered by the contact of superincumbent lava, its horizontality and extent.—Subsequent volcanic eruptions, associated with calcareous matter in an earthy and fibrous form, and often enclosed within the separate cells of the scoriae.—Ancient and obliterated orifices of eruption of small size.—Difficulty of tracing over a bare plain recent streams of lava.—Inland hills of more ancient volcanic rock.—Decomposed olivine in large masses.—Feldspathic rocks beneath the upper crystalline basaltic strata.—Uniform structure and form of the more ancient volcanic hills.—Form of the valleys near the coast.—Conglomerate now forming on the sea beach. II.—FERNANDO NORONHA; TERCEIRA; TAHITI, ETC. FERNANDO NORONHA.—Precipitous hill of phonolite. TERCEIRA.—Trachytic rocks: their singular decomposition by steam of high temperature. TAHITI.—Passage from wacke into trap; singular volcanic rock with the vesicles half-filled with mesotype. MAURITIUS.—Proofs of its recent elevation.—Structure of its more ancient mountains; similarity with St. Jago. ST. PAUL’S ROCKS.—Not of volcanic origin.—Their singular mineralogical composition. III.—ASCENSION.