6 B. B. WEATHERBY AND L. Y. FAUST 
Ideal conditions for determining the velocity-depth function can be 
approximated by velocity measurements of the section of Pennsyl- 
vanian sediments between the Hogshooter and the Oswego. This 
section is fairly constant in its lithologic character throughout central 
Oklahoma. The average lime content of the section in the wells where 
velocity measurements were available was 14 per cent with a maxi- 
mum variation in any well of 3 per cent from this mean. The average 
thickness of the section was 750 feet. Figure 3 represents the differ- 
ential velocity obtained in this section plotted against the mean 
depth below the surface of the section. 
LIMESTONE VELOCITIES 
Except for the work of Weatherby, Born, and Harding’ in the 
measurement of the longitudinal velocity of Arbuckle limestone, little 
work has been done on the accurate measurement of surface velocities 
in limestone. The data available on surface limestone velocities is 
listed in Table ITI. 
TABLE III 
SURFACE LIMESTONE VELOCITIES 
Age Velocity (Ft./Sec.) 
Cambro-Ordovician (Arbuckle)* 17,400 
Ordovician (Viola) 16,700 
Devonian (Hunton) 4,000 
Mississippian (Mayes) 12,500 
Pennsylvanian (Belle City) 15,000 
Cretaceous (Edwards) II,000 
With the exception of the Pennsylvanian value these velocities 
follow the age of the limestones in an orderly fashion. The greater 
velocity of the Pennsylvanian may be due to its having been under 
a few feet of cover while the rest of these velocities were determined 
on surface exposures. It should be noted that these velocities may 
be in rather serious error due to surface weathering and erosion. 
TABLE IV 
VELOCITIES IN LIMESTONE 
Age Velocity Mean Depth of 
(Ft./Sec.) Section 
Measured 
(Feet) 
Ordovician 20,000 4,000 
Devonian 17,500 4,500 
Mississippian 17,000 4,700 
Pennsylvanian 15,500 3,000 
Permian 15,500 3,900 
Cretaceous 13,500 3,300 
3B. B. Weatherby, W. T. Born, and R. L. Harding, Bull. Amer. Assoc. Petrol. 
Geol., Vol 18, No. 1 (January, 1934), p. 106. 
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