20 ROCK GARDENING FOR AMATEURS 



a better example for us to follow. Variation revealing 

 the essential form of stratification is, then, the aim. 

 When employing flat rocks, between the fissures of which 

 plants are to be grown, do not have the strata level, for 

 in such a case any soil between the layers becomes dried 

 up readily ; give them a slope and plants will establish 

 themselves easily, sending their roots down to the soil 

 below. 



The grouping of a mixed quantity of rocks makes 

 a difficult problem for the beginner. He must select them 

 a little ; unless they are all stratified, or all unstratified, 

 he should place them in two heaps composed respectively 

 of the different kinds. As a general rule keep the stratified 

 for one corner of the work, the unstratified for the other, 

 and combine the two groups by a rock construction in 

 which a gradual change from one type to the other does 

 not strike the eye as being peculiar and out of place. 

 Often the evils of sudden changes from a sedimentary 

 basis to a volcanic formation are noticed, and the result 

 is scarcely ever pleasing. Groups of one kind of rock 

 interspersed in rockeries composed chiefly of the other 

 have the same result, and seldom look well. One might 

 think that this scientific selection is unworthy of con- 

 sideration when a small rockery is being built, and that 

 anything will do ; but a rockery is an artistic creation, 

 and as such it has established itself in the heart of the 

 modern aesthetic gardener. Any kind of paint will 

 cover a canvas, but blending, harmony, and the right 

 colours make a picture. 



