THK SOIL OF THE FAUM. 395 



The importance of this fact to the agriculturist is at once apparent, 

 when we find that each stratum in turn occupies the surface of the coun- 

 try . It is the constant order of succession which makes the arrangement 

 of the various formations of practical use to the land- valuer or the agri- 

 culturist. 



Some geological formations yield soils of high average fertility, while 

 others yield inferior soils. Some are stiff and expensive to work, while 

 others are generally free working. It must, however, be remembered that 

 geological knowledge, although useful, is not entirely to be relied upon. 

 On all formations, good, bad, and indifferent soils are no doubt to be met 

 with. The mingling of formations together at their edges, accumulation 

 of drifted matter, the occurrence of less important strata, unnoticed per- 

 haps in the geological chart, and other reasons, create numerous excep- 

 tions to any rule which may be laid down with respect to the soils of a 

 certain geological formation. The subject is full of interest, and deserves- 

 a longer notice than we can at present afford it. 



4. PHYSICAL PROPERTIES OF SOILS, AND SURROUNDING CONDITION-. 



THE PROXIMATE CONSTITUENTS OF SOILS. Soils differ widely from each 

 other in their physical properties. Some are wet and consequently cold ; 

 others are warm and dry ; some are easily worked, while others are 

 exceedingly tough; some are easily burnt up by drought, while oil 

 maintain a thriving herbage through the most trying seasons. The phy- 

 sical nature of a soil depends upon the proportion in which its proximate 

 constituents are blended. All soils are composed of five pro ximate in^iv- 



ts; namely: (1) Sand, (2) Clay, (3) Lime, (4) Vegetable matter, (o) 

 Mineral fragments (stones). Whether derived from the decay of chalk or 

 sandstone, it will be found that all fertile soils are thus constituted, and 



kind and quality of the soil depends to a great extent upon the pro- 

 portion in which thus*- materials are mixed together. A short account of 



6 familiar substances becomes therefore very necessary if we ;u 

 arrive at a sound conclusion regarding the nature of soils. 



i may he cither cal.-areous, micaceous, or siliciou^. A ealctt 

 sand simply means a sand in which particles of lime, it may be shell 

 chalk, al.ouii'l. Many MA sands are <.f this nature aii'l may l.e applied t 

 land a- a BOUTC6 of lime. Tun- >an<l IB, howeTOT, frer t'i <i\\ lime, ami C 



alm>t exclusively of small grains nf ftilicfo acid qtUUTtl . It 

 in it -ilver sand, ami is accumulated in <|uant it ies wl. 



parate.l fmrn cartliy matter l.y the action of water. It 



