BY DR. J. V. DANES. 77 



by water, by help of sand, gravel and rock debris, and are 

 full of potholes of very diversified size and aspect. In 

 old caves, the traces of the mechanical action are generally 

 obliterated ; the old channels are filled by loam, sand and 

 secondary limestone, the walls covered by secondary 

 limestone, and numerous, often beautiful and picturesque 

 stalactites and stalagmites give the most attractive appear- 

 ance to old caves. Gradually the roofs give way to pressure, 

 and often in old limestone areas there occur long, narrow, 

 precipitous gorges, which were caves before the collapse 

 of upper layers of rocks. Blind valleys are the result of 

 such a process, and also broad level basins* occur in some 

 extensive limestone areas with rivers and creeks, which 

 on one side leave the subterraneous passage, and on the 

 other side disappear once more under the continuous 

 barrier of rocky ridges. 



Many limestone mountains represent rocky deserts,, 

 whose passage is very (difficult, there being no definite 

 valleys, which generally form the most important ways of 

 communication in rugged mountainous countries. 



Where the limestone rocks are devoid of vegetation,, 

 the chemical and mechanical action of the falling rain- 

 w^aters affects the surface in a peculiar way. 



The edges and corners of limestone blocks look as if 

 worked by a fine chisel, and later develop deep correlated 

 forms ; extremely sharp and fine ridges fall abruptly 

 into miniature valleys or basins, which generally end at 

 a fissure or a cavity, where the water disappears into the 

 underground depths. 



This phenomenon is very well developed, especially 

 on many barren limestone ridges and plateaus in the Alps, 

 and is known under the name of " Karren " to the Germans, 

 and " Lapiaz " to the southern Frenchmen. f All those 

 forms of terrain, which form the peculiarity of the 

 physiographical character of the limestones, are known 

 as the " Karst phaenomena," " Karst " or " Eras " is a 



South Slavish word designating a barren, rocky 

 country, and was originally applied to the vast limestone 



♦Such basins are called '• poljes," and occur along ihe Adriatic coast, 

 in the French Jura, and in Jamaica. The greatest " Livanjskopolji" in 

 Western Bosnia covers about 180 square miles. 



t In the Adriatic Karst. 



