Sir H. H. Hoioorth — Geological History of the Baltic. 559 



to question his argument and conclusions either, which, like mine, 

 are merely tentative. 



He goes on to argue further that, during the period since the 

 Litorina sea was initiated, the climate of Scandinavia has become 

 distinctly colder, if it has changed at all, and he even seems to adopt 

 Ekholm's suggestion that it has become colder to the extent of 

 reducing the midsummer temperature to the extent of 2 degrees 0. 



Whatever the quantitative value of the suggestion, the external 

 and supplementary evidence seems to me to amply sustain the main 

 contention of the Norwegian writers, and to show that for a long 

 time past, whether it be for 6,000 or 8,000 years, and not impossibly 

 the latter, the climate of Scandinavia has been growing colder and 

 not growing warmer. 



Let us shortly turn to this supplementary evidence. In the first 

 place, then, it seems to me that the dominating climatic factor in 

 terrestrial areas depends very largely upon their latitude, an element 

 which is fixed, and their elevation above the sea-level, which is 

 variable. The higher the land, especially in high latitudes, the 

 lower, cceteris paribus, the mean temperature. This is an elementary 

 •axiom of meteorology. Inasmuch as the Scandinavian lands in the 

 Litorina time were more submerged than, and not so high above the 

 water in the Central and Northern Baltic as, they are now, it follows 

 inevitably that the mean climate of the land, in so far as it was 

 affected by its height above the sea-level, was warmer in the Litorina 

 time than it is now. 



Secondly, in northern latitudes salt water has a higher mean 

 warmth than fresh water ; the latter, again, freezes much more easily, 

 and supplies, therefore, a great refrigerator in Winter, when the Salter 

 water is more open. Inasmuch as the feature of the Litorina time in 

 the Baltic was the greater salinity of that sea, it follows that as the 

 Baltic has been becoming less saline it has also become cooler, so 

 that in both respects the tendency has been in the direction of a 

 severer climate. 



A third element, working in the same direction, is caused by the 

 fact that the inflowing water from the North Sea is itself warmer as 

 a whole than the outflowing water from the Baltic, and as the former 

 was present in larger proportionate quantities in the Litorina time 

 than now this again confirms the same conclusion. 



Let us now turn to the fauna and flora of Scandinavia and see 

 what it tells us. There cannot be a doubt that since the Baltic 

 breach took place the fauna and flora of the Scandinavian peninsula 

 and of the Baltic islands has not been in a position to receive fresh 

 recruits and accessions from beyond the sea. The peopling of such 

 isolated areas by the vagabonds of the biological world seems to 

 me to be a quite fantastic idea, and the number of land plants and 

 animals (other than regular or irregular migrants from the classes 

 of birds and insects) which have reached the lands in question since 

 the land-bridge was broken down must have been insignificant. 



We may accept the present fauna and flora of Scandinavia and the 

 Baltic islands, therefore, as a fair measure of what the climate of 



