On Chalk Marl 



549 



numerous small fissures In the rock, which constitute a natural 

 drainage. It is one of the richest subsoils of the whole chalk series, 

 being admirably adapted for the growth of hops, wheat, beans, &c. ; 

 and indeed nearly the whole of the outcropping of this subsoil from 

 P'arnham to Petersfield is under cultivation for the first-named 

 crop. When exposed to frost this rock crumbles into a fine 

 powder. In the neighbourhood of Farnham, during the last ten 

 , years, many thousands of tons have been dug and used as a ma- 

 nure, under the impression that it was a " good marl this is 

 so far mistaken as rejjards the meaninof of the word marl, which, 

 correctly speaking, should only be applied to a substance contain- 

 ing much carbonate of lime. All those persons who have em- 

 ployed it concur in expressing a favourable opinion of its effects, 

 and particularly on some sandy soils the benefit derived from its 

 application is most striking. That we are not to attribute this 

 eff(ect to the presence of lime in any form, is evident from the 

 composition of the substance as given below. 



At the present time it is still extensively quarried for manure. 

 This section of rock at Farnham is about 40 feet in thickness, 

 and as it approaches the next stratum above it gradually assumes 

 a harder character, and does not so readily moulder into soil by 

 exposure. 



Analysis of Soft Brown Rock immediately above the Gault (No. 4). 



Per Cent. 



Combined water and a little organic matter . 4* 15 



Soluble in dilute acids, 57*10: — 



Silicic acid (silica) 46*28 



Carbonic acid none. 



Sulphuric acid ...... trace. 



Phosphoric acid , ditto. 



Chlorine ....... none. 



Lime 0*26 



Magnesia . . . . . . . '07 



Potash -79 



Soda -43 



Protoxide and peroxide of iron . . . 6*12 

 Alumina .3*15 



Insoluble in acids, 38*75 : — < 



Lime 2-91 



Magnesia traces. 



Potash 1-51 



Soda -60 



Alumina with a little oxide of iron . . .14*20 

 Silicic acid and sand . . , . .19*53 



100*00 



No. 5. The Firestone Rock. — The next in the ascending series 

 is the firestone rock, which is hard, heavy, and compact. It is 

 much esteemed, locally, as a good building-stone, which may be 



