U.S. GEOLOGICAL SURVEY 
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LEGEND. 
Underlain byPotomacWaters deeper than 50 Ft 
Crystalline Rocks 
C atchment Area of Lower Pot o mac waters 
• Successful wells 
O Unsuccessful wells. 
The heavy blue Contours indicate position of crystalline 
rocks in relation to the level below which they pass at 
the Zero line 
The figures in red indicate depths of wells 
The figures in black indicate number of wells in list 
of wells. 
Scah 
2 MILES 
MAP OF BALTIMORE REGION ILLUSTRATING FWk 
