22 
ARTESIAN WELLS ON THE ATLANTIC COAST. 
[bull. 138. 
In fig. 4 a condition is illustrated which is in a measure similar to 
that shown in section 1, fig. 2. The water-bearing beds lie in channels, 
as it were, with intervening belts of nonwater-bearing materials. In 
this case wells at A and A would be successful, but those at B and B 
would not be. 
Figure 5 represents a condition which is no doubt quite frequent on 
Long Island among the drift deposits. The conditions would appear to 
be favorable at A for water in the gravels between the upper clay beds, 
but the water does not accumulate, for it is free to flow over the edge 
of the clay into lower gravels, where it would be found in a deeper 
well, as at B. 
Ideal section illustrating the occurrence of local clay strata in gravels and sands. 
In fig. 6 a condition is shown which is frequently met with along 
the western border of the Coastal Plain in Maryland and northern Vir- 
ginia. The water-bearing beds lie above sea level and are cut across 
Fig. 6. — Ideal section illustrating waterbearing beds intercepted by a valley. 
by a depression, so that the water may escape in springs. Accord- 
ingly, a well at B would usually find but little water, notwithstand- 
ing the fact that a well at A finds an abundant supply in the same 
beds. 
NEW YORK. 
As this report is intended to cover only the Coastal Plain region 
of the Atlantic Slope, in the restriction of the term to the province 
underlain by the Cretaceous and Tertiary deposits, this chapter should 
relate only to Long Island and southern Staten Island. As, however, 
I have incidentally obtained some data for many of the wells on New 
York Island, a list of these wells will also be given. 
