528 PREHISTORIC EUROPE. 



now maritime regions, but the very general destruction that 

 befell the forests of the inland districts can hardly be due to that 

 submergence alone. That the climate had become considerably 

 colder, may reasonably be inferred from the reappearance of 

 snow-fields and local glaciers in Scotland ; and that it was also 

 wetter, may be gathered from the fact that peat-bogs then over- 

 spread wide areas, in which nowadays they do not grow, but are 

 mouldering more or less rapidly away. 



The gradual disappearance of this cold and inclement epoch 

 was marked by the slow retreat of the sea. The climate at the 

 same time again favoured the growth of great forests — the 

 remains of which are traced not only in the peat of our inland 

 districts, but even in that of the maritime regions. "We can 

 hardly doubt that at the time when those trees were growing 

 the land extended farther out to sea — in other words, the sea 

 had retreated to a lower level than its present tide-mark. The 

 buried trees in the peat of the English coast-lands bear emphatic 

 testimony in this direction. Distinct traces of this second forest- 

 growth are observable, as we have seen, in the inland districts. 

 It is somewhat noteworthy, however, that while in Scotland oak 

 is common at the bottom of the peat-bogs, not only in the low- 

 lands, but even in upland and highland areas, the same tree 

 appears to be generally wanting in the upper forest-layers, at 

 least in the higher-lying parts of the country, and this rule holds 

 true also for many lowland districts. Mr. Kinahan and others 

 have made the same observation in Ireland. The most charac- 

 teristic tree of the upper forest- layers in the peat -bogs of 

 Scotland, more especially in the upland districts, is the pine 

 (Pinus sylvestris), and this is the case also in Ireland. Mr. Blytt 

 has recorded precisely the same fact in south-western and 

 southern Norway. In those regions oaks and alders occur at 

 the bottom of the bog, which is of variable thickness and 

 formed of aquatic and marsh-loving plants. Above this under 

 portion comes a second forest-layer composed chiefly of pines, 

 which are in their turn buried under a second bed of sphagnum- 

 peat. Lindeberg and Olbers tell us of exactly similar pheno- 



