114 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



Thanks to the bend towards the south which characterises the 

 coux'se of the isothermal lines in these parts, the north-eastern 

 point of Scotland enjoys a temperature several degrees higher 

 than that of the south-western extremity of Scandinavia, the 

 most temperate portion of the latter country. We can therefore 

 say that heat conditions are more favourable in Scotland than in 

 Scandinavia. As for the rainfall, it is practically equal in the 

 two countries, and its variations are parallel, Scotland being 

 divided into a moister western portion and a drier eastern portion, 

 and Scandinavia being divisible in a similar manner. 



If we compare the direction and the force of the winds, the 

 parallel is not unfavourable to the Highlands. In a word, the 

 analysis of the principal climatic factors reveals a striking 

 analogy in their course and relative influence. There is, there- 

 fore, from this standpoint, no reason why Scotland should not be 

 as well wooded as Scandinavia. 



Let us next consider the geological data. We can group 

 Norway, Sweden with the exception of Skane, and Finland as a 

 single mass superficially separated at present by the Bothnic 

 depression, but as having formed a continental area since Silurian 

 times. A large portion of this Scandinavian group belongs to the 

 crystalline rocks known in their entirety under the name of 

 Archaean rocks. In the second rank comes the Precambrian 

 system, occupying nearly a tenth of the surface. We have there- 

 fore almost everywhere a substratum of granite, gneiss, and 

 mica-schist. 



While, in Norway, the drifts cover scarcely a tenth, at the 

 most, of the surface of the country, in Sweden nearly the whole 

 of the forest soil is made up of glacial till. The morainic gravels 

 and clays form good arable land. 



We need change these general features very little irx order to 

 identify them with those of the Scottish Highlands. And it is 

 impossible to say that the geological conditions are more un- 

 favourable to forest vegetation in the Highlands than in the 

 Scandinavian countries. 



Now Scandinavia has always been covered with vast and 

 vigorous forests. In the southern part of the peninsula the beech 

 finds favourable conditions up to the altitude of 300 ^ m. The oak 

 foi'ms forests, the upper limit of which is still at 500 ^ m. in GO" 

 N. lat. As we ascend, we cross the coniferous zone, which, on the 

 -average, does not extend beyond 600^ m., with Finus sylvestris 

 1 1000 feet. - 1600 feet. ^ 2000 feet. 



