832 UTILIZATION OF STONE, GKAVEL, ETC. 



with clay they are used for cement. Quarries of gypsum, felspar 

 and kaolin are rare. 



2. Mode of Utilization. 



Stone is obtained either by quarrying the mountain-side, in 

 deep quarries, or by collecting boulders or flint-nodules from 

 the surface of the ground. From a silvicultural point of view, 

 permanent quarries are greatly preferable to the employment 

 of boulders, as the area taken from the production of wood is 

 then of limited extent and more easily controlled : the growth 

 of wood being permanently excluded from the area, no question 

 of indirect injury to the forest can arise. Direct injury to the 

 forest may, however, occur in quarrying in the experimental 

 search for suitable localities for a quarry ; the loss of wood 

 production on areas which are often extensive ; the damage to 

 roads, and occasionally the increase in forest offences owing 

 to the presence of the quarry-men in the forest. 



The quality of stone from the same geological formation 

 may vary considerably in different parts of the same moun- 

 tain-side ; hence several experimental quarries are frequently 

 commenced and eventually abandoned. This causes loss of a 

 considerable area for wood-production, as when the soil is 

 covered with fresh unweathered rock it is often impossible 

 to restock it with trees. Even when a workable quarry has 

 been started, often fairly large areas are required for deposit 

 of the refuse stone, and on steep slopes the latter often 

 accumulates in long strips down the valleys, as in the 

 Siebengebirge. 



This nuisance may, however, be improved by good regula- 

 tions and confined within reasonable limits. It is therefore 

 indispensable that not only the quarry itself, but the area on 

 which refuse may be thrown should be demarcated carefully. 

 Forest offences by quarry-men, who are sometimes imper- 

 fectly acquainted with the limits of mine and thine, cannot 

 be avoided altogether. Considerable damage also is done to 

 the forest roads, no traffic being more ruinous to them limn 

 that of stones from quarries. The latter are not usually im- 

 portant enough to warrant the construction of roads specially 

 made for them alone ; hence the nearest forest road is used, 



