INTRODUCTION ΤΟ GEOLOGY: COMPRISING THE ELEMENTS OF THE SCIENCE IN ITS PRESENT ADVANCED STATE, AND ALL THE RECENT DISCOVERIES; WITH AN OUTLINE OF THE GEOLOGY OF ENGLAND AND WALES. BY ROBERT BAKEWELL. THE THIRD EDITION, ENTIRELY RECOMPOSED, AND GREATLY ENLARGED. WITH NEW PLATES. LONDON: PRINTED FOR LONGMAN, REES, ORME, BROWN, AND GREEN, PATERNOSTER-ROW. PREFACE TO THE THIRD EDITION. THE First and Second Editions of the Introduction to Geology were favourably received, and sold off, soon after their publication. The work has since been translated and published in Germany, by Mr. Frederick Muller of Friburg; but it has been long out of print in this country. The causes which have retarded the publication of a Third Edition it is unnecessary to mention: the delay has, I trust, been favourable to its appearance in a very improved state; as I have been collecting materials for it, during several years, having visited almost every situation of much geological interest in our own island, from the Land's End in Cornwall, to the Grampian Mountains in Scotland; and passed part of three years in examining the geology of Savoy, Switzerland, and France. There is scarcely a rock formation described in the present volume, that I have not examined in its native situation, and compared with the descriptions of former geologists. I have also had opportunities of examining the collections, and of profiting by the communications, of |