BULLETIN OF THE AMERICAN ASSOCIATION OF PETROLEUM GEOLOGISTS 
VOL. 19, NO. 1 (JANUARY, 1935), PP. 9-18, 6 FIGS. 
EFFECT OF MOISTURE UPON VELOCITY OF ELASTIC 
WAVES IN AMHERST SANDSTONE! 
W. T. BORN anp J. E. OWEN? 
Tulsa, Oklahoma 
ABSTRACT 
Laboratory measurements of the velocity of elastic waves in Amherst sandstone 
show that the bar velocity is dependent on the moisture content, the velocity decreasing 
as the moisture content is increased. Bar velocities ranging from 7,640 to 4,415 feet 
per second were observed. It is shown that the change in velocity is caused primarily 
by a change in the value of Young’s modulus of the material. The suggestion is made 
that this phenomenon may have some bearing on the question of Gulf Coast reflection 
surveys. 
INTRODUCTION 
In the course of a program of work being carried on at the labora- 
tory of the Geophysical Research Corporation to determine the 
velocity of elastic waves in various materials, it was found that one 
of the samples used showed variations in velocity from day to day of 
an amount entirely too great to be accounted for by experimental 
errors. The determinations were made with the sample in an air-dry 
condition and it was therefore suspected that the velocity variations 
observed might be caused by a change in the moisture content of the 
sample due to varying atmospheric conditions. This supposition led 
to the work here described. 
DESCRIPTION OF SANDSTONE 
The sample used was a bar of Amherst sandstone approximately 
2 inches square and 4 feet long. This rock is fine-textured sandstone 
of Triassic age, outcropping in the Connecticut Valley. The sample 
was one of a number obtained from a local stone cutter who, unfor- 
tunately, was unable to specify the exact location from which it was 
obtained. The density of a dry sample of this material was found to 
be 1.92. To obtain an idea of the total porosity of the stone, a sample 
1 Read before the Geophysics Division of the Association at the Dallas Meeting, 
March 23, 1934. 
2 Geophysical Research Corporation. The writers wish to extend their thanks to 
Miss Margeret C. Cobb and Bruce H. Harlton, both of the Amerada Petroleum Cor- 
poration, for their study of the rock section, and also to Parker D. Trask and K. E. 
Lohman of the United States Geological Survey for their kindness in furnishing the 
photomicrographs. 
9 669 
