ABSTRACT OF VOLUME. XXI 



deeply into the underlying rock formations. This necessitates a classification of the 

 underground waters and a description of the several rock formations penetrated, 

 including a discussion of the attitude of the strata. The essential conditions for 

 obtaining artesian wells are considered, and also the relation of the drift to the 

 ordinary wells. There is a brief discussion of gas wells, confined mainly to tliose 

 obtained in the drift. A tabulation of sources for city water supply is then presented, 

 after which there appears a detailed discussion of wells, taken up by counties. 



Chapter XV. Soils. — The sources of soil material are first discussed. An 

 attempt is then made to classify the soils according to their origin. Eight classes are 

 recognized, as follows: Residuary soils, bowlder-clay soils, gravelly soils, sandy soils, 

 bluff-loess soils, silts slowly pervious to water, fine silts nearly impervious, peaty or 

 organic soils. 



