MEDITERRANEAN 283 



alfa plateau. Such areas correspond to a rainfall below 

 16 inches. The most important are found in the Ebro 

 valley, in La Mancha, and on the south-east coast. The 

 high ' Meseta ' plateau, another centre of low rainfall, 

 is equally arid and treeless. 



Illyrian Karst. The Highlands of Illyria, Albania, 

 and Greece separate the Mediterranean from central 

 Europe. A series of limestone ranges, rising sharply 

 from the Adriatic and shaping its eastern shore, run in 

 a general north-west to south-east direction, forming 

 many longitudinal terraces and scarps, deep valleys, lofty 

 plains, stony depressions and rugged highlands ; they 

 sink gradually to the north-east into the hilly lowlands 

 of the Save and Danube. Here the prevalence of lime- 

 stone rock entirely controls the nature of the relief and 

 largely that of the vegetation. The rock is full of cracks, 

 fissures, caverns, and holes of all sizes, through which 

 rain-water sinks too rapidly, leaving the surface dry. 

 When torrential downpours sweep across the country, the 

 overflow comes rushing down the steep slopes, washing 

 away the loose soil and depositing it over the closed 

 plains or 'poljes'. Scarcity of soil naturally renders 

 vegetation both stunted and scattered, and confines it 

 largely to valleys and terraces. These conditions of 

 sheer slope, porous rock, and scanty soil, resulting from 

 the soluble nature of the limestone, impart to the vege- 

 tation a much drier aspect than it would possess other- 

 wise. According to the elevation three climatic zones 

 may be distinguished : a lower or Mediterranean, a mid- 

 dle area whose climate corresponds to that of the low- 

 lands of central Europe, and a higher mountain belt 

 corresponding to the Alps. As features of this region 

 are to be counted the bora and the sirocco : the former 

 a dry icy blast sweeping down, in winter, from the snow- 



