OF ROCKS. 223 



Rocks are proverbially associated with barrenness, 

 though there is no rock but which, if left at rest and 

 watered, will produce its plants nay, a succession 

 of races ; and if the climate were favourable, .and 

 we could wait long enough, there is not the least 

 doubt that we could water a rock till it became so fer- 

 tile on the surface that we could sow it with grain, 

 or plant it with vegetables. Pebbles in a brawling 

 stream, or rolled on the beach by the waves, are 

 unproductive things certainly ; and not merely that, 

 for they wear one another ; but examine the very 

 same kind of pebbles in a shallow standing pool, or 

 on a part of the beach where they are left at rest, 

 and you will find that they have their plants and 

 their animals. The mountain rocks, even in the 

 coldest places, are covered with lichens, some of 

 which are of value in the arts, and others as articles 

 of food. Many dying materials are obtained from 

 those curious "productions, some of which are in 

 themselves not easily distinguished from the rocks 

 on which they grow. 



The common people in the northern countries 

 have long been in the habit of dying their stuffs with 

 these substances; and in their hands the colours 

 that are produced are very durable, though not very 

 brilliant. The orchal, or French rock-moss (Lichen 

 parellus, of Linnaeus), which forms a very white, 

 rough, and warty crust on the rocks, and might, by 

 a careless observer, be taken for a patch of mortar, 

 produces very beautiful shades- of crimson and pur- 

 ple; and cudbear (Lichen tartareus), which forms 

 grayish patches, is found so valuable in giving a 

 bloom to colours, that there are manufactories for 

 the express purpose of preparing it, and people who 

 resort to the rocks and earn their living by scraping 

 it off. Hard as it is, it grows much faster than would 

 be supposed ; and the cultivator of it (if he can be so 

 called) has little labour compared with other cultiva- 

 tors, as he has merely to come and scrape the rocks 



