30 C. E. VAN ORSTRAND 
100° F. is reached. The numbers on the left of the locations represent 
feet per degree Fahrenheit. 
Very rapid rates of temperature increase have been found at Lost 
Soldier and Thermopolis, Wyoming. At Thermopolis, the writer made 
tests in g wells located on the tops of the two Warm Springs domes, 
Hot Springs County, Wyoming. The depth-temperature curves are 
practically the same in all of the wells. Six of the curves are shown in 
Figure r1. All of the curves in the figure have been drawn on the same 
scale, but the origin for each curve has been displaced to the right for 
the sake of clearness in representation. The two wells in which curves 
A and B were obtained are located 10 or 12 miles northwest of the 
Warm Springs domes. As the Big Horn hot springs, one of the largest 
hot springs in the world, is about 5 miles west of the oil fields, the 
movement of water over the domes may be of very great importance. 
CAUSES OF TEMPERATURE VARIATIONS 
Three distinct types of variation have been discovered, namely, 
variation in the vertical, and variations over both large and small 
areas. 
The dependence of the distribution of temperatures in the vertical 
on the porosity of the rocks and on the rise of air temperatures since 
the ice age is discussed in previous paragraphs. The precision with 
which the rock temperatures are adjusted to the air temperatures 
above them is indicated by the fact that the mean of 514 values of e 
(Table III), distributed throughout the United States, exclusive of 
the Powell oil field, Texas, and the oil fields of California, is —1.54°F. 
The data from the Powell oil field are believed to be erroneous. The 
mean value of e for 144 wells in the California oil fields is —8.44° F. 
The cause of this large value is not known. By assuming it to be an 
error, and adding 1° F. to the observed annual mean temperature of 
the air, the following corrected reciprocal gradients are obtained. 
Bakersfield 53-8 Long Beach 43-1 
Coalinga 45-9 Santa Fe Springs 45-7 
Fullerton 46.9 Seal Beach 42.6 
Huntington Beach 34.6 Whittier 48.2 
Kettleman Hills 42.6 
As these numbers are much less than the corresponding numbers in 
Table III, it follows that the evidence in support of the hypothesis of 
a variation of temperature over these structures is greatly strength- 
ened if it is assumed that the large value of e is due to drilling and pro- 
ducing operations. 
Another marked variation in the vertical is shown in Figure 4. 
Here the rise in the depth-temperature curve is almost imperceptible 
552 
