342 Sir H. E. Eoivorth—The Baltic— The Ancylm Sect. 



which has occurred in other Ancylus beds (Nathorst, Sveriges 

 Geologi, pp. 258-266). 



De Geer has calculated that the Ancylus sea extended over 

 570,000 square kilometres (220,000 miles), and included the whole 

 Baltic area with Finland and Lake Ladoga (see Nathorst, op. cit., 

 pp. 258 and 259, where a map of the Ancylus sea is given). 



The facts here mentioned, and others similar to them, have 

 satisfied the Northern geologists that the recent history of the Baltic 

 involves its having been first a widely spread fresh-water sea and 

 then a brackish -water one, more salt than the present Baltic, which 

 has gradually become less salt until it acquired its present condition. 



The change here mentioned, from a fresh- water sea to a brackish 

 one, involved one inevitable corollary, namely, that at a not 

 remote time in its history the Baltic must have been entirely shut 

 off from the North Sea and been a completely enclosed lake. This 

 conclusion, again, has been found to exactly harmonize with other 

 evidence forthcoming from other sources, and which I will shortly 

 condense. 



Anyone who looks at the broken and irregularly outlined Danish 

 islands, separated by their narrow sounds and belts and partially 

 closing up the space between Jutland and Skane in Sweden, will be 

 impressed by their resemblance to a ruinous remnant of a formerly 

 continuous land surface. This appearance is fully borne out by the 

 actual evidence, which proves that the whole area has sunk con- 

 siderably in comparatively recent times. A movement of elevation 

 subsequently intervened and affected a portion of the sunken surface. 

 This is very plainly shown by the fact that all along the coast of 

 Skane and elsewhere in this area the marine beds of recent origin, 

 which are found at a small elevation above the sea and whose shells 

 show they belong to the Litorina period, frequently lie upon turf or 

 upon beds containing land shells and land plants, as has been pointed 

 out by many observers. This proves that the district in question, 

 which was once dry land, has at one time been sunk below the water 

 sufficiently deeply and long to get a covering of marine deposit upon 

 it, and has been then raised again to its present level. The first 

 person who argued that the land ofi" the coast of Skane had sunk 

 was J. C. Wilcke, who, writing in 1770 in regard to the harbour of 

 Landskrona, notices how in the banks bounding its entrance and 

 which are covered by five or six feet of water there are found trunks 

 of rotten and upright trees, showing that the submerged ground was 

 once a wood, and tells us how he had been told in 1767 that a large 

 oak with its trunk and branches intact had been found under six 

 feet of water. 



On the oyster ground Wilcke found decayed trunks in a layer of 

 submerged mould, in which they had probably grown, and he con- 

 sidered the layer of soil marked the former level of the land, which 

 had therefore been about five feet below the main level of the 

 water. These facts led him to the conclusion that there had been 

 a considerable subsidence along the coast. 



In 1847 Nilsson published his well-known work on the 



