DARTON] 
LOCAL CONDITIONS AFFECTING WELLS. 
21 
region are often widely bared in other areas and receive ample water 
supply diagonally down the dip. 
There are many local conditions that affect individual wells or small 
areas which should be illustrated here, for they are often referred to in 
the following pages. They are represented in the sections in fig. 3. 
Sfctio/v / 
Gravek 
Section 2. 
Fig. 3.— Ideal sections illustrating certain special conditions affecting well prospects. 
Section 1 represents a gravel bed merging into clay or fine sand in a 
circumscribed area. Wells atB and 0, and probably at D, would find 
water-bearing gravels on the crystalline rock floor, whereas at A there 
would be clays all the way down and no water would be obtained. In 
some cases at A the gravels might continue, but with a clay matrix 
which excludes the water. 
Fig. 4. — Ideal section illustrating water-bearing beds in channels. 
Section 2 represents the occurrence of a gravel bed which is com- 
pletely inclosed in clays, so that no water can accumulate in it, and a 
well at A, although finding favorable materials for water, would obtain 
none. 
