3G0 ON THE MOVEMENTS OF THE EARTH .S CRUST. 



eiiand, and near the shore thick deposits can be formed in a .short 

 time. 



The profiles of Eoussillon (by Deperet, in Ann. Sci. Geol. 7o\. xvii. 

 1885) show four alternations in the stage contemporaneous with the 

 Coralline Crag (arc 14'). The overlyiiig stage in Roussillon is a fresh- 

 water formation. The land had risen. The fresh-water stage has sev- 

 eral alternations, probably six to eight, so far as I can see from the 

 profiles given, which, however, are not quite accurately described (arcs 

 15', 16'). 



We now turn again to England. The fossils of the Red Crag show 

 a colder climate than that of the Coralline Crag, and the Chillesford 

 beds, which belong to the last portion of the Red Crag, have distinctly 

 arctic shells. The Glacial epoch was advancing. After the Red Crag 

 was formed, England again rose and became united by land with the 

 continent. Extinct mammals wandered in its forests, which consisted 

 of existing trees (spruce, pines, etc.) and show a temperate climate, 

 milder than that of the Chillesford beds, and about as at present. " The 

 forest bed of Cromer " was overlain by marine deposits — Westleton 

 Shingle and Cromer Clay (arc 16'). In the latest terrestrial formation 

 at Cromer Nathorst has found Arctic plants {Salix polaris, etc.), and 

 the Cromer Clay indicates the vicinity of inland ice. With this the 

 Pliocene closes. 



As regards the Quaternary oscillations, we will take the English de- 

 posits as described by J. Geikie (" Great Ice Age," ed. 2, pp..387 etseq.) 

 as our guide. 



The Quaternary period commences with the retrogression of the ice and 

 with a considerable denudation. Then the sea again rose and covered 

 a great part of the east of England. The inland ice again extended 

 itself and formed a bottom-moraine, " the great chalky bowlder-clay " 

 (arc 1"). After this glacial period an elevation of the land seems to 

 have followed, and the ice retreated. But a new depression followed 

 (Bridlington Crag) and a new glacial period (purple bowlder-clay, arc 

 2"), A fresh elevation seems to have followed, with a new interglacial 

 period. Then came a new depression, which was very considerable, 

 and which at Moel Tryfaen in Wales, at Macclesfield, and in Ireland 

 has left marine shells at heights of 1,000 to 1,300 feet above the sea 

 (nearly approaching that at which the old " seter " or beach-lines in 

 Osterdalen, Ltesje, etc. occur). Like the preceding depression, this was 

 also followed by a glacial period, the last (Hessle bowlder-clay, arc 3"). 

 Finally the laud rose and the ice melted. The Post-glacial period came 

 with its four peat-beds (the last portion of 3" and 1"). To arc 4" cor- 

 responds a small oscillation of the sea immediately before the recent 

 period. In Scania, Giiravallen, a raised beach-formation, rests upon 

 peat; in Gotland, in the British Islands (Carse Clay, etc.), and even in 

 North America, we may trace the same oscillation of the sea; it was no 

 doubt too great to be capable of exi)lanation by local conditions, com- 

 pression of peat-beds by shifting sand-dunes, etc. 



