Entered according to the act of congress, in the year 1837, by James Kay, Jun. & Brother, in the Philadelphia: Printed by James Kay, Jun. & Brother, THE original MS. of the Principles of Geology was delivered to the publisher in 1827; but the greater portion of it was then in an unfinished state, the chapters on the early history of Geology, and those on "the Inorganic Causes of Change," being the only ones then nearly ready for the press. The Work was at that time intended to form two octavo volumes, which were to appear in the course of the year following. Their publication, however, was delayed by various geological tours which I made in the years 1828, 1829, 1830, and 1831, in France, Italy, Sicily, and Germany. The following were the dates when the successive volumes and editions finally appeared: I have acknowledged on former occasions the valuable assistance afforded me by several of my friends in the execution of this work, and have especially returned my thanks to Mr. Murchison, Mr. Broderip, Dr. Fitton, Mr. Lonsdale, and Capt. Basil Hall, for their zealous co-operation, and for the corrections and improvements which were adopted at their suggestion. In the Prefaces to the third and fourth editions, I gave List of the principal Alterations and Additions in the Fifth Humboldt on preservation of animals in frozen mud Stranding of icebergs on west coast of Iceland Raised beaches in Carlingford Bay, Ireland Omission of remarks on the origin of the valleys of the Moselle and Account of Edmonstone Island corrected Arago on causes of currents, and on relative level of the Red Sea and On the formation of Shingle beaches Dr. Daubeny on a volcanic band across the Italian peninsula . Account of the earthquake in Chili, February 1835, added; with Map Dr. Meyen on proofs of elevation of land in Chili, 1822 On the effects of earthquakes in the excavation of valleys, recast Account of the subsidence of Greenland enlarged Dr. Beck on the great range of some species of testacea Erman on the level of the Caspian Account of Submarine Forests, transferred to this place from Chap- Loess of the Valley of the Rhine, the whole recast with additions 86 107 266, 267 301, 302 Slope of recent strata in the modern delta of the Kander in Lake of Crag of Norfolk and Suffolk, and overlying deposit. The whole of 312 313 M. Dufrénoy on the tertiary strata of the basin of the Gironde 344, 345, 346 Note on the latest opinions respecting an alleged difference of level between the Caspian and Black Seas Professor Sedwick and Sir J. Herschel on the causes of the cleavage of rocks 392, 393 486, 487 A general view or summary of the contents of this work cannot fail to be useful in pointing out more clearly the course of reasoning adopted, and the order in which the different subjects are treated. I therefore hope that the student, by referring from time to time to the subjoined summary, will more easily understand the plan of the whole, and the bearing on geology of several digressions which I have introduced on collateral topics, especially on certain departments of natural history. GENERAL VIEW OR SUMMARY OF THE PRINCIPLES OF GEOLOGY. After some observations on the nature and objects of Geology (Chap. I. Vol. I.), a sketch is given of the progress of opinion in this science, from the times of the earliest known writers to our own days (Chaps. II. III. IV.). From this historical sketch it appears that the first cultivators of geology indulged in many visionary theories, the errors of which are referred chiefly to one common source, a prevailing persuasion that the ancient causes of change were different, both as regards their nature and energy, to those now in action. In other words, it was supposed that the causes by which the crust of the earth, and its habitable surface, were modified at remote periods, were almost entirely distinct from the operations by which the surface and crust of the planet are now undergoing a gradual change. The prejudices which led to this assumed discordance |