NORMAL GEOTHERMAL GRADIENT 79 
c’’c'c) rise in passing over the anticlines. Expressed in terms of gradi- 
ents, this is the equivalent of saying that the gradients are a maxi- 
mum, or the reciprocal gradients are a minimum, along the crests of 
the anticlines. 
ee i Ss 
RUIN iS \ }sl 
OOBAU SS ONG SS ee 

Fic. 1.—Cross section of typical anticline. 
Variations in the vertical are illustrated by the concave and 
convex types of depth-temperature curves (A A’ and BB’) shown in 
Figure 2. Each of the lines cc and ee represents the least square 
adjustment of a straight line through all of the observed points from 
8&8 No.5700, Hope Natural Gas Co, 
Yo/cano, West Virginia 
Total! Depth=4400 Ff. Aya 
TEMPERATURE ° FAHRENHEIT 
VA 
Jon 
lean Temperature 
Fic. 2.—Concave and convex types of depth-temperature curves. 

4500 
DEPTH —- FEET 
100 to 1,000 feet inclusive on the respective curves. Similarly, the 
lines dd and ff were obtained by adjusting, in each case, a straight 
line through all of the points from too feet to the greatest depth, 
inclusive, at which a reading was taken. In curves of the concave 
739 
