PART L] CULTURAL 109 



rise. The high cliffs are in places worn into deep caves, in 

 others slender pillars of rough rock have been separated from 

 the main mass, and stand solitary on the beach, while larger 

 islands of rock stand out at sea, through which arches of every 

 size and shape have been excavated. No rock can be better 

 suited for rock-gardens if used rightly, and it is moreover 

 known that its chemical composition is such as to be very 

 beneficial to rock-plants. These magnesian limestones are 

 called Dolomites, and it is notable that their fantastic shapes 

 are by no means confined to England, since no mountain range 

 is so remarkable for abruptness and startling variety of con- 

 figuration as that in the Italian Tyrol, known as the Great 

 Dolomites. Besides the hard old stony limestones of which 

 we have spoken, there are in England a number of other kinds, 

 from the oolitic limestones to the chalk, which can occasionally 

 serve the landscape gardener's purpose. Their appearance is 

 too well known to need description here. In the newer 

 geological series there are frequently beds of a light porous 

 limestone, very similar in appearance to the sinter which is 

 deposited by petrifying springs. In many places this is called 

 " ragstone," and it is extremely well adapted for our purpose ; 

 their distribution is, however, very local in Britain, so that, 

 according to our theory as to aesthetics of rock-gardens, they 

 cannot be very widely used. Abroad, in Tertiary districts, they 

 are far more common, especially on the shores of the 

 Mediterranean, both on the European and on the African 

 side. 



SCHISTS AND SHALES. 



These may, for the purposes of rock-building, be considered 

 together; the former being simply the hardened and altered 

 form of the latter. Their weathered appearance, where exposed, 

 varies very much with the angle of their dip and with the 

 degree of crystallisation to which they have attained. Some 

 schists are quite as crystalline as granite, and they then weather 

 in the same manner, with this proviso, that the lines of folia- 



