Cornwall, Devon, and West Somerset. 27 



between Ilfracombe and Bull Pointy on the south of the last^ is, 

 again, less fertile, while that which succeeds it in the ascending 

 series, and which is chiefly composed of fine argillaceous slate, is 

 generally not much inferior ; being, however, liable to form a 

 clayey soil where the natural drainage is not good. The next 

 band, principally formed of sandstones, and ranging from the 

 coast at Morte Bay and Baggy Point, to Heydon and Main 

 Downs, near Wiveliscombe, presents generally a poor soil ; while 

 the band above it, extending from the vicinity of Barnstaple, by 

 Dulverton and Raddington, to Bathealton, and which is often 

 calciferous, is frequently fairly fertile. 



On the south, the differences of soil, from variations in the 

 mineral structure of the grauwacke and its associated trappean 

 rocks, is still more remarkable ; and we may here observe that 

 the latter rocks, which are chiefly compounds of hornblende and 

 felspar, afford the most fertile soils of any in the district, when 

 their decomposition has taken place to any sufficient depth ; so 

 much so, that when much disintegrated, they are sometimes 

 worked as marl-pits for manure, and the land thus treated is 

 always found to be greatly benefited. The trappean ash, par- 

 ticularly when mingled with calcareous matter, which is some- 

 times the case, affords a remarkably fine soil.''' The trappean 



* I had an opportunity last autumn of observing this trap-rock at my 

 friend Sir Thomas Acland's place near Exeter. In the quarry it has the 

 appearance of volcanic lava, and sometimes of ashes; and though its fiery 

 origin is infinitely more ancient than any existing volcano, you might sup- 

 pose while standing on it that you were at the foot of Vesuvius. The stones 

 from this quarry at Killerton had been found to act excellently as a dress- 

 ing for corn-land : and the soil over this rock was stated by the bailiff to be 

 worth 105, an acre more than the neighbouring land. Professor Johnston 

 has found the same circumstances in Scotland. " In the neighbourhood of 

 Haddington," he says, " I have seen a farming- tenant removing 12 inches 

 of trap soil from the entire surface of a field for the purpose of spreading a 

 layer of an inch in depth over twelve times the area in another part of his 

 farm." "The same general character," he also states, "is exhibited by the 

 trappean soils of other parts of the island. The height of the Cheviot Hills 

 renders the climate in many places unfavourable to arable culture, yet they 

 produce the sweetest pasture, while the low country around them has been 

 largely benefited by admixture with their crumbling fragments. The 

 whole of that lowland tract of Scotland over which these rocks extend, com- 

 prehending the counties of Ayr, Renfrew, Lanark, Linlithgow, Fife, and 

 portions of Perth, Stirling, Edinburgh, and Haddington, exhibit the fertile 

 or fertilising character of the decomposing greenstone. Professor Johnston 

 informs us that, according to Dr. Riippell, the only fertile tracts of Abyssinia 

 are found in valleys and on mountain slopes, where the soil is composed of 

 the washings of trap-rocks ; and he adds, " The more modern volcanic lavas, 

 which overspread Italy, Spain, and Germany, are closely related to the 

 trap-rocks in their general composition, and the fertility wliich overspreads 

 thousands of square miles of decomposed lava-streams and ejections of vol- 

 canic ashes in Italy and Sicily is too well known to require any detailed 



