THE ROCK WORK 75 



tion, a few winters' frosts and rains will work 

 them loose and a quantity of the soil be washed 

 out, to the great detriment of whatever is 

 growing in it. This applies chiefly to the 

 larger fissures, for in the smaller ones the soil 

 is less likely to be dislodged. 



A number of the rarer alpines, however, so 

 dislike moisture lying about their crown that 

 they can only be grown successfully in this 

 type of fissure ; the chief difficulty is to get 

 the plant well established ; but once it is 

 established, the roots will help to keep the 

 soil in position and the leaves protect it from 

 being washed away by the action of the rain. 



The oblique and horizontal fissures are, on 

 the other hand, quite easy to make, and prove 

 very satisfactory. Of the two the oblique is to 

 be preferred, as it ensures utiHsing all available 

 moisture. 



On studying the face of a quarry, it will 

 be seen that there is a certain uniform grain 

 or strata running through it ; this may vary 

 greatly in form, and is very much more marked 

 in some kinds of rock than in others. In 

 limestone it is very apparent, and in a less 



