CHAP. XVII. POST-GLACIAL DISLOCATIONS. 341 CHAPTER XVII. POST-GLACIAL DISLOCATIONS AND FOLDINGS OF CRETACEOUS AND GEOLOGICAL STRUCTURES OF THE ISLAND OF MÖEN -GREAT DIS- AND GLACIAL DRIFT-DIFFERENT DIRECTION OF THE LINES OF SUCCESSIVE - N the preceding chapters I have endeavoured to show that IN the study of the successive phases of the glacial period in Europe, and the enduring marks which they have left on many of the solid rocks and on the character of the superficial drift, are of great assistance in enabling us to appreciate the vast lapse of ages which are comprised in the postpliocene epoch. They enlarge at the same time our conception of the antiquity, not only of the living species of animals and plants, but of their present geographical distribution, and throw light on the chronological relations of these species to the earliest date yet ascertained for the existence of the human race. That date, it will be seen, is very remote if compared to the times of history and tradition, yet very modern if contrasted with the length of time during which all the living testacea, and even many of the mammalia, have inhabited the globe. In order to render my account of the phenomena of the 342 FOLDINGS OF STRATA CHAP. XVII, glacial epoch more complete, I shall describe in this chapter some other changes in physical geography, and in the internal structure of the earth's crust, which have happened in the post-pliocene period, because they differ in kind from any previously alluded to, and are of a class which were thought by the earlier geologists to belong exclusively to epochs anterior to the origin of the existing fauna and flora. Of this nature are those faults and violent local dislocations of the rocks, and those sharp bendings and foldings of the strata, which we so often behold in mountain chains, and sometimes in low countries also, especially where the rockformations are of ancient date. Post-glacial Dislocations and Foldings of cretaceous and drift Strata in the Island of Möen, Denmark. A striking illustration of such convulsions of post-pliocene date may be seen in the Danish island of Möen, which is situated about fifty miles south of Copenhagen. The island is about sixty miles in circumference, and consists of white chalk, several hundred feet thick, overlaid by boulder clay and sand, or glacial drift which is made up of several subdivisions, some unstratified and others stratified, the whole having a mean thickness of sixty feet, but sometimes attaining nearly twice that thickness. In one of the oldest members of the formation, fossil marine-shells of existing species have been found. Throughout the greater part of Möen, the strata of the drift are undisturbed and horizontal, as are those of the subjacent chalk; but on the north-eastern coast they have been, throughout a certain area, bent, folded, and shifted, together with the beds of the underlying cretaceous formation. Within this area they have been even more deranged than is the English chalk with flints along the central axis CHAP. XVII. IN THE ISLAND OF MÖEN. 343 of the Isle of Wight in Hampshire, or of Purbeck in Dorsetshire. The whole displacement of the chalk is evidently posterior in date to the origin of the drift, since the beds of the latter are horizontal where the fundamental chalk is horizontal, and inclined, curved, or vertical where the chalk displays signs of similar derangement. Although I had come to these conclusions respecting the structure of Möen in 1835, after devoting several days in company with Dr. Forchhammer to its examination, I should have hesitated to cite the spot as exemplifying convulsions on so grand a scale, of such extremely modern date, had not the island been since. thoroughly investigated by a most able and reliable authority, the Danish geologist, Professor Puggaard, who has published a series of detailed sections of the cliffs. These cliffs extend through the north-eastern coast of the island, called Möens Klint,† where the chalk precipices are bold and picturesque, being 300 and 400 feet high, with tall beech-trees growing on their summits, and covered here and there at their base with huge taluses of fallen drift, verdant with wild shrubs and grass, by which the monotony of a continuous range of white chalk cliffs is prevented. In the low part of the island, at A, fig. 47, or the southern extremity of the line of section above alluded to, the drift is horizontal, but when we reach B, a change, both in the height of the cliffs and in the inclination of the strata, begins to be perceptible, and the chalk No. 1 soon makes its appearance from beneath the overlying members of the drift Nos. 2, 3, 4, and 5. This chalk, with its layers of flints, is so like that of England as to require no description. The incumbent *Lyell, Geological Transactions, 2nd series, vol. ii. p. 243. † Puggaard, Geologie d. Insel Möen, Bern, 1851; and Bulletin de la Société Géologique de France, 1851. 344 STRUCTURE OF ISLAND OF MÖEN: CHAP. XVII. drift consists of the following subdivisions, beginning with the lowest : No. 2. Stratified loam and sand, five feet thick, containing at one spot, near the base of the cliff at s, fig. 48, Cardium edule, Tellina solidula, and Turritella, with fragments of other shells. Between No. 2 and the chalk No. 1, there usually intervenes a breccia of broken chalk flints. No. 3. Unstratified blue clay or till, with small pebbles Fig. 47 A B Southern extremity of Möens Klint (Puggaard). A Horizontal drift. B Chalk and overlying drift beginning to rise. c First flexure and fault. Height of cliff at this point, 180 feet. Fig. 48 TALUS D Section of Möens Klint (Puggaard), continued from fig. 47. s Fossil shells of recent species in the drift at this point. and fragments of Scandinavian rocks occasionally scattered through it, twenty feet thick. No. 4. A second unstratified mass of yellow and more sandy clay forty feet thick, with pebbles and angular polished and striated blocks of granite and other Scandinavian rocks, transported from a distance. No. 5. Stratified sands and gravel, with occasionally large C CHAP. XVII. M. PUGGAARD'S SECTIONS. 345 erratic blocks; the whole mass varying from forty to a hundred feet in thickness, but this only in a few spots. The angularity of many of the blocks in Nos. 3 and 4, and the glaciated surfaces of others, and the transportation from a distance attested by their crystalline nature, proves them to belong to the northern drift or glacial period. It will be seen that the four subdivisions 2, 3, 4, and 5, begin to rise at B, fig. 47, and that at c, where the cliff is 180 feet high, there is a sharp flexure shared equally by the chalk and the incumbent drift. Between D and G, fig. 48, we observe a great fracture in the rocks with synclinal and anticlinal folds, exhibited in cliffs nearly 300 feet high, the drift beds participating in all the bendings of the chalk; that is to say, the three lower members of the drift, including No. 2, which, at the point s in this diagram, contains the shells of recent species before alluded to. Near the northern end of the Möens Klint, at a place called 'Taler,' more than 300 feet high, are seen similar folds, so sharp that there is an appearance of four distinct alternations of the glacial and cretaceous formations in vertical or highly inclined beds; the chalk at one point bending over, so that the position of all the beds is reversed. But the most wonderful shiftings and faultings of the beds are observable in the Dronningestol, part of the same cliff, 400 feet in perpendicular height, where, as shown in fig. 49 (p. 346), the drift is thoroughly entangled and mixed up with the dislocated chalk. If we follow the lines of fault, we may see, says M. Puggaard, along the planes of contact of the shifted beds, the marks of polishing and rubbing, which the chalk flints have undergone, as have many stones in the gravel of the drift, and some of these have also been forced into the soft chalk. The manner in which the top of some of the arches of bent chalk have been cut off in this and several adjoining sections, attests the |