THE PINE AND OTHER CONHERS. 297 



Conifers ; and to the South of the Pine region, there is 

 the vast extent of country formerly covered by Oak 

 forests. Still further South, on the Mediterranean 

 coastline, we find a flora of Sweet Cliestnuts, of Olives 

 and Vines, and a climate which is very much more 

 genial than that of Central Europe. All these great 

 associations, or Floras, may be looked upon as arrested 

 on their journey north after the retreating Ice Sheet, 

 and upon their border lines they are contending with 

 one another for the use of the soil. 



In many respects, greater height above the sea acts 

 on plants in the same way as a more Northern latitude. 

 Thus, even on such minor mountains as are met with in 

 the Highlands of Scotland, we find at the very summit 

 arctic-alpine plants ; below these a part of the mountain 

 inhabited by heather and peat moss; lower still, bracken- 

 covered pasture, once probably covered by Pine forests ; 

 and in the most sheltered valleys. Oaks and deciduous 

 trees. What actually happened seems to have been 

 somewhat as follows. When the glaciers and their 

 attendant alpine-arctic Mosses and Lichens gradually 

 passed northwards, the Pine forests advanced behind 

 them, and eventually occupied the whole country driving 

 the alpine-arctic forms to the summits of the hills. 



The Pines were then invaded, and dispossessed of the 

 more sheltered valleys by Oaks and other plants. The 

 Beech and a whole host of other trees are now found 

 covering parts of the lowlands which were once in all 

 probability occupied by the Oak-forest. Thus the 

 present distribution shows a sort of zonal arrangement 

 which may be well followed on the map in Geikie's 

 Scenery of Scotland. 



It will be seen that some six distinct vegetations are 

 here recognised which are as follows : 



