Method of generalising. 387 



should always be to state the natural history of that country ; 

 because on soil, surface, and climate is founded all vegetable 

 culture. It may seem almost trifling, to notice the geology of 

 a tour of a few miles in one's own country ; but we do so, as 

 we do many other things in this Magazine, for the sake of 

 inducing the young gardener to think scientifically on every 

 subject connected with his profession or general welfare. 



The London clay extends beyond Harrow and Pinner, 

 where it is succeeded by chalk with flints ; this is in some 

 parts covered with gravel, the surface of the clay being flat, 

 or gently undulated, with some rising nodules, of which the 

 most conspicuous is Harrow Hill. The surface of the gravel 

 and chalk is more wavy than that of the clay. The soil on 

 both is loamy or clayey, and that on the chalk is mixed with 

 flints. The chalk continues to within a few miles of Ayles- 

 bury, where a lower stratum of clay succeeds, and extends some 

 miles beyond that town ; the surface beirjg generally even, and 

 the soil a strong loam. Earthy limestone now begins, and con- 

 tinues, through Buckingham, half way to Banbury; this be- 

 longs to what geologists denominate the oolite limestone form- 

 ation ; the surface gently varied, and the soil rather stiff, but 

 generally on a dry subsoil. Red sandstone and a dry brown 

 light soil succeed, and continue through Birmingham and the 

 coal country beyond, to the neighbourhood of Ashbourne. 

 Here the hard semicrystalline limestone of Derbyshire, with 

 all its singularities of formation and stratification, vrith its 

 caverns, pits, beds of volcanic toadstone and basalt, and 

 metallic veins commences, and continues till we reach the 

 neighbourhood of Stockport in Cheshire, where we again 

 enter on the sandstone, which continues to Manchester. No 

 hilly country occurs in this route till we arrive near Cheadle, 

 with the exception of some small cultivated hills near Bir- 

 mingham, Bromsgrove, Stourbridge, and Dudley. From 

 Cheadle to Ashbourne the country is very irregular, with 

 numerous winding narrow valleys, having rocks protruding 

 from their sides ; beyond Ashbourne towards Dove Dale, the 

 surface becomes very hilly and naked, and continues so to 

 Chapel in le Frith. The elevated bleak aspect of the Peak 

 in Derbyshire used to be well known. It is now almost 

 entirely enclosed by stone walls, and covered with pasture 

 and plantations. Approaching Stockport, the view of Cheshire 

 and Lancashire conveys the idea of a fertile and highly culti- 

 vated plain on sandstone. 



The variety of indigenous plaiits, as seen from the road, in 

 all this tract of country is much less than might be imagined ; 

 partly because a ditch and hedge form a sort of artificial 



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