ENGLISH AGRICULTURE. 23 



to the valleys, and deposited, forming a level and fertile 

 valley witness the valley of the Rhone. 



I have endeavoured to describe the action of the natural 

 forces which have gradually given us the loose material that 

 covers the surface of the planet. It would be a mistake 

 indeed to imagine that soil is merely pounded rock ; or that 

 by putting rocky material through a mill we would obtain 

 soil. Two conditions are necessary before pounded rock can 

 be converted into fertile ground. These two conditions are, 

 first, time, and secondly, vegetation. Before we can have a 

 soil such as I speak of, we must not only have certain forces 

 disintegrating and breaking down rock, but ample time must 

 be allowed. 



First, then, with reference to time. If we can imagine a 

 sample of soil to be before us, we should observe that it is 

 made up of fragments of various sizes. It contains a large 

 number of mineral fragments, and very little reflection will 

 show that these fragments form a descending series as to 

 size, from pebbles and stones of varying size, down to minuto 

 chips requiring the magnifying-glass to render them apparent. 

 Now, these mineral fragments are parts of the original rock 

 from which the soil was derived, and they are all continually 

 exposed to the same cosmic forces which, in the first instance, 

 broke down the continuity of the parent rock. And if we 

 fix our attention upon those minuter fragments which might 

 require the microscope to make them evident, we shall have 

 no difficulty in understanding that there must be a perpetual 

 passage from a condition of compactness to a state of solution. 

 There is a gradual and constant disintegration, and therefore 

 a constant passage from minute but compact material to a 

 soluble state ; and this continuous process is what we refer to 

 when we speak of the constituents of the soil changing from a 

 dormant, or, as it may well be termed, a "potential" condition 

 of plant food into what is designated an " active," but which 



