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Other alluvial parts are quite fertile when drained, but 

 swampy when not. Above 1,500-2,000 feet the typical 

 leathery-leaf vegetation gradually gives way to a sum- 

 mer-green landscape which covers most of the hill-lands, 

 depressions, and slopes up to 3,800 feet. This is the 

 temperate oak belt which, wrapping round the ranges of 

 high mountains, reappears on their eastern and northern 



Fig. 111. Limestone slopes on the Adriatic. 



sides and spreads over the uplands draining to the Save 

 and Danube, and the middle valleys draining to the Aegean 

 Sea. Great havoc has been wrought among these de- 

 ciduous oak forests on the Mediterranean slopes, but 

 extensive timber areas still persist on the Danube side. 

 The karst-forest includes, beside oaks, characteristic 

 forms such as the manna-ash, various kinds of maples, 

 and hornbeams; it is frequently replaced by scrub, 



