THE ARTESIAN WATER SUPPLY OF EASTERN FLORIDA. 135 
Fig. ii.—Map of flowing area of Nassau and Duval Counties. The area; 
in which flowing wells can be obtained is indicated by shading. 
DUVAL COUNTY. 
LOCATION AND SURFACE FEATURES. 
Duval County joins Nassau County on the south, and is sepa¬ 
rated from it by the Nassau River and its tributary, Thomas 
Creek. The St. Johns River flows through Duval County. The 
surface drainage from this county is carried off largely through 
these rivers and their tributaries. 
The surface is in general flat or but slightly rolling. The 
surface elevation rises gradually from sea level. The highest ele¬ 
vation reached is found in the southwestern part of the county 
