BY CHARLES LYELL, Esq. F.R.S. FOREIGN SECRETARY TO THE GEOLOGICAL SOCIETY OF LONDON. "The inhabitants of the globe, like all the other parts of it, are subject to PLAYFAIR, Illustrations of the Huttonian Theory, § 413. IN FOUR VOLUMES. VOL. II. THE THIRD EDITION. LONDON: JOHN MURRAY, ALBEMARLE STREET. Educ T20290.357530 v.2 AUG 13 1921 HARVARD COLLEGE LIBRARY GIFT OF GEORGE ARTHUR PLIMPTON JANUARY 25, 1924 PRINCIPLES OF GEOLOGY.' BOOK II. CHANGES OF THE INORGANIC WORLD. PART I.- AQUEOUS CAUSES - continued. CHAPTER VII. ACTION OF TIDES AND CURRENTS - continued. Action of tides and currents, continued-Inroads of the sea upon the delta of the Rhine in Holland-changes in the arms of the Rhine Estuary of the Bies Bosch, formed in 1421 Formation of the Zuyder Zee, in the 13th century Islands destroyed - Delta of the Ems converted into a bay - Estuary of the Dollart formed Encroachment of the sea on the coast of Sleswick - Inroads on the eastern shores of North America - Tidal wave, called the Bore Influence of tides and currents on the mean level of seas Action of currents in inland Baltic-Cimbrian deluge― Straits of Gibraltar lakes and seas -No under-current there Whether salt is precipitated in the Mediterranean - Waste of shores of Mediterranean. Inroads of the sea at the mouths of the Rhine. - THE line of British coast considered in the preceding chapter offered no example of the conflict of two great antagonist forces; the entrance, on the one hand, of a river draining a large continent, and on the other, the flux and reflux of the tide, aided by a strong current. But when we pass over by the Straits of Dover to the continent, and proceed northwards, we find an admirable illustration of such a contest, where the Rhine and the ocean are opposed to each other, each disputing the ground now occupied by Holland; the one striving to shape out an estuary, the other to form a delta. There was evidently a period when the river obtained the ascendency, when the shape of the coast and set of the tides were probably very different, but for the last two thousand years, during which man has witnessed and actively participated in the struggle, the result has been in favour of the ocean, the area of the whole territory having become more and more circumscribed; natural and artificial barriers having given way, one after another, and many hundred thousand human beings having perished in the waves. Changes in the arms of the Rhine. The Rhine, after flowing from the Grison Alps, copiously charged with sediment, first purges itself in the Lake of Constance, where a large delta is formed; then, swelled by the Aar and numerous other tributaries, it flows for more than six hundred miles towards the north: when, entering a low tract, it divides into two arms, not far north of Cleves a point which must therefore be considered the head of its delta. In speaking of the delta I do not mean to assume that all that part of Holland which is comprised within the several arms of the Rhine can be called a delta in the strictest sense of the term; because some portion of the country thus circumscribed, as, for example, a part of Gelderland, consists of tertiary strata which may have been deposited in |