On the Agricultural Geology of England and Wales. 453 



intimate connection than usual subsists between the soils and the 

 rocks on which they rest. We find, accordingly, that Sir H. De la 

 Beche takes the substratal view of the origin of soils, supposing- 

 them to have resulted from the decomposition of the subjacent 

 rock in situ. He observes, however, of the chalk and greensand 

 on the eastern borders of the district, that they are so overlaid by 

 transported gravel as to possess a common agricultural character 

 very different from that of the more eastern chalk districts, and 

 bv no means one of fertility. He mentions also other scattered 

 deposits of gravel (besides the stream tin gravel of the valleys) 

 in other parts of Devon and Cornwall. It is needless to enume- 

 rate more particularly the other points of that Report bearing on 

 agriculture, because they have been republished by Sir H. De la 

 Beche in the Journal of the Royal Agricultural Society, and have 

 been more than once referred to by agricultural writers in that 

 Journal. By far the greater part of the agricultural geology of 

 England and Wales at present known is to be found in Mr. 

 Morton's work on Soils, which has served as a text-book to most 

 subsequent writers on the subject. It contains much valuable 

 information respecting soils, the result of personal observation, 

 and many useful hints for their improvement, but it falls into the 

 prevailing error of drawing general conclusions from limited in- 

 ductions, and assigning too much influence to the rock formations, 

 and too little to the superficial deposits. 



The points insisted on are, that the nature and colour of the soil 

 partake of that of the subjacent rock, the principal mineral being 

 that of the geological formation beneath — so that argillaceous soils 

 rest on the clay formations, calcareous soils on the chalk, and 

 oolites and siliceous soils on the various sandstones ; the colour 

 also of the soils being those of the rocks on which they repose — 

 white on the chalk, red on the new red sandstone, and on the 

 sands and clays in general nearly of the same colour as that of 

 the stratum below. Any differences which exist are referred to 

 the presence of animal or vegetable matter, or to exposure to the 

 atmosphere and oxidation of the iron contained in the strata. This 

 connection between the soil and the subjacent rock is insisted on 

 as forming the best foundati(m for a classification of soils ; many 

 attempts, it is alleged, having been made to classify them on other 

 principles, which have failed to convey to the mind either of the 

 practical farmer or scientific agriculturist any correct idea of their 

 nature and properties. Local names are therefore preferred by 

 the author, and he proposes to classify soils by referring them to 

 the geological formation on which they rest. 



Diluvium is defined to be a vast accumulation of sand, gravel, 

 and other materials which are found covering in masses some of 

 the older and continuous geological formations to a greater or less 



