Subsurface Methods as Applied in Geophysics 



1057 



contrast as measured is not sufficient to explain the magnitude of the 

 anomaly, and either the sediments have retained some remanant magnetiza- 

 tion or higher susceptibilities must exist at depth. 



From gravity data the dome is a symmetrically shaped salt mass, 



Figure 556. Thomasville magnetic anomaly in northern Clarke County, 

 Alabama. (Adapted from Eby and Nicar.) 



with its upper and lower bases at depths of about 215 feet and 15,000 

 feet and the radii from 4,000 to 2,500 feet.^^ 



Thomasville Anomaly, Clarke County, Alabama — One of the better 

 examples of magnetic anomalies that are not associated with structure is 

 afforded by the large symmetrical magnetic anomaly lying in the northern 



" Peters, J. P., and Dugan, A. F., Gravity and Magnetic Investigations at the Grand Saline Salt 

 Dome, Van Zandt Co., Texas: Geophysics, vol. 10, no. 3, pt 376, July 1945. 



