22 



GEOLOGICAL REPORT. 



[139 



and those of underlying or adjacent forma- 

 tions ; which plainly prove that the current 

 which first denuded the more ancient forma- 

 tions and then deposited the Orange Sand, 

 sometimes re-deposited the materials first 

 removed, without effecting any great change 

 in their lithological character, or removing 

 them to any great distance from their original 

 place. 



I have stated above (1[25), that where the 

 Orange Sand is in contact with clayey strata 

 of underlying formations, clays closely resem- 

 bling those of the latter are often found 

 unequivocally connected, by stratification, 

 with the Orange Sand deposits. This is so 

 commonly true, that in North Mississippi, 

 where I have most closely observed the 

 formation, the occurrence of these bluish 

 clays is taken as a sign of the approach to the 

 surfice of the " black dirt," warning the well- 

 digger not to proceed any further, for fear of 

 spoiling the quality of his water by contact 

 with the fetid bituminous clays of the Ligni- 

 tic. Similarly, in Tishomingo county, it is 

 often impossible to determine within many 

 feet, the line between the greenish sands of the 

 lower Middle Cretaceous, and the overlying 

 Orange Sand ; and in several cuts on the 

 Memphis and Charleston E. E., it is clearly 

 shown that cretaceous sands, unchanged save 

 in their stratification, have been redeposited 

 on the previously denuded surface of older 

 strata ; retaining in part at least, their lime, 

 and also their characteristic fossils. 



39. Diagram No. 2, representing a cut on 

 Harris' contract, S. 3 T. 3 E. 9 E., will serve 

 to exhibit these phenomena, which are repeat- 

 ed in many other cuts in the same region. 



It will be observed that the undisturbed 

 cretaceous material (a dark-colored, very 

 compact sandy clay), which has evidently 

 been subject to denudation, is overlaid by 

 variegated sand (similar to that which, further 

 W., forms the undisturbed strata of the 

 Cretaceous), the stratification of which con- 



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