bOlL AND SUBSOIL. 177 



an examination of which should therefore precede every pur- 

 chase of land, or planting of crops. 



Such examinations are most quickly made by means of a probe con- 

 sisting of a pointed, square steel rod five or six feet long, provided at 

 one end with a loop for the insertion of a cross handle like that of a 

 carpenter's auger. The handle being grasped with both hands, the 

 probe is forced into the soil with a slight reciprocating motion, by the 

 weight of the operator; who socn learns how to interpret the varying 

 kinds of resistance, and on withdrawing the probe carefully will generally 

 be able to determine if bottom water has been reached. Should this 

 easy method of examination not convey all the needful information, the 

 pesthole auger may be resorted to ; and it is desirable that extra (three- 

 foot) rods or gaspipe joints be provided for the purpose of lengthening 

 the probe or auger, when necessary, to nine or twelve feet. It will 

 rarely be necessary to go to the trouble of digging a pit for such exam- 

 inations ; but even this is to be recommended rather than " buying a 

 cat in a bag " in the guise of an unexplored subsoil. 



Faulty Substrata. A number of examples of " faulty 

 lands," /. c., such as are underlaid by faulty substrata, are 

 given in the annexed djagram Fig. 35 ; the examples being 

 taken from California localities because of their having been 

 most thoroughly investigated. Similar cases, as well as others 

 not here illustrated, of course occur more or less all over the 

 world. 



Xo. I shows a case which, though at first sight an aggravated 

 one of a rocky substratum, is in reality that of some of the best 

 fruit lands in the State. The limited surface-soil is very rich, 

 and is directly derived (as a "sedentary" soil) from the 

 underlying bedrock slate. But this it will he noted stands on 

 edge, and the roots of trees and vines wedge their way along 

 the cleavage planes of the slate to considerable depth, deriving 

 from them both nourishment and moisture. Under similar 

 conditions the California laurel, usually found on the banks of 

 streams, grows on the summits of rocky ridges in the Coast 

 Ranges. 



The case of Xo. J is quite otherwise. Here the shale lies 

 horizontally, and though much softer than the slate of the first 

 column, obstinately resists the penetration of roots; so that the 

 land, though fairly provided with plant-food, is almost wholly 



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