470 



SEISMIC METHODS 



[Chap. 9 



Table 50 

 SANDSTONES AND SHALES 



Table 51 

 LIMESTONE, GYPSUM, ANHYDRITE, CHALK, SALT 



" These velocities may be in entH' as much as SOS m./8eo. (or 1000 ft./8ec.) because of surface weathering 

 and erosion. 



