152 INSECT PESTS 



from the active intelligent interest which smallholders 

 and growers as a body cannot help taking in all that 

 concerns Uving things, an insight into the modus operandi 

 of nature does help in catering for the welfare of the 

 crops we are anxious to produce. 



To begin with, then, soil, with a marvellous history 

 contained in each tiny particle, consists of two main sub- 

 stances, organic and inorganic. Of these, the latter, the 

 mineral portion, is the result of both chemical and mechani- 

 cal processes carried on through countless centuries of 

 time. For instance, before there was any soil as we 

 know it to-day on this infinitesimal but highly important 

 portion of the earth's surface known as England, there 

 was the parent rock. We need not go into the details 

 of the many changes from submarine to dry land condi- 

 tions that are clearly indicated in any quarry cutting, 

 as it will not help us much, and can be left to the geologist 

 to study ; but to-day, after all these various changes, 

 through almost interminable lengths of time, certain 

 parent rocks now he immediately underneath our soil, 

 and determine to a large extent the nature of that soil! 



England and Wales, broadly speaking, is divided into 

 six or seven principal bands of surface strata. Altogether 

 our country has been highly favoured by nature, for 

 there is a greater variety and a more complete geological 

 sequence here than is found in any other similar tract 

 in the whole world. 



Taken in their correct order, we will commence at 

 the Old Red Sandstone, which underhes the greater 

 portion of the West Country, Bristol and the South Wales 

 districts and also extends in a narrow belt right across 

 Scotland from the Firth of Clyde to the mouth of the 

 Tay. All these districts are orchard country, whence 

 it is inferred that fruit growing is most profitable over 

 sandstone. 



Next we get the limestone and millstone grit, which 

 characterizes the landscape of the Pennine Chain, and 



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