256 FERTILITY DEPENDENT ON GEOLOGICAL STRUCTURE. 



On these hard slate and gneiss rocks extensive pine forests in Sweden and 

 Norway have long lived and died. In these countries it is customary in many 

 places to burn down the wood, to strew the ashes over the thin soil, to harrow 

 in the seed — to reap thus one or two harvests of rye, and to abandon it aga^n to 

 nature. A grove of beech first springs up, which is supplanted'by an after- 

 growth of pine, and finally disappears. 



Such is a general description of the nature and order of succession of 

 the stratified rocks, as they occur in Great Britain and Ireland — of the 

 relative areas over which they severally appear at the surface — and of 

 the kind of soils which they produce by their natural decay. The con- 

 sideration of the facts above stated,* shows how very much the fertility 

 of each district is dependent upon its geological structure — how much a 

 previous knowledge of that structure is fitted to enlighten us in regard to 

 the nature of the soils to be expected in any district — to explain anoma- 

 lies also in regard to the unlike agricultural capabilities of soils a{)par- 

 ently similar — to indicate to the purchaser where good or better lands 

 are to be expected, and to the improver, whether the means of amelio- 

 rating his soil by limeing, by marling, or by other judicious admixture, 

 are likely to be within his reach, and in what direction they are to be 

 sought for. There still remain some important branches of this subject 

 to which, at the risk of fatiguing you, it will be my duty briefly to draw 

 your attention in the following lecture. 



* For much of the practical information contained in this section, I have to express my 

 obligations to the following works:— For the extreme soathern counties, to De La Deche's 

 Geological Report on Cornwall and Devon ; and to a paper by Sir Charles Lemon, Bart., on 

 the Agricultural Produce of Cornwall ;— for Wales and the Border counties, to Murchison's 

 Silurian System; — for the Midland counties of England, to Morton on Soils, a work I have 

 in a previous note recommended to the attention of the reader; for Yorkshire, to a paper by 

 Sir .lohn Johnston, Bart., in the Journal of the Royal Agricultural Society ,•— and for the Old 

 Red Sand-stone of the north of Scotland, to the very interesting little work of Mr. Miller on 

 IVie Old Red Sarulstone. The reader would read the above section wfth much greater 

 profit if he were previously to possess iiimself of Phillip's Outline Map of the Geology of the 

 British Islands. 



