6 GEOLOGICAL REPORT. [H"7, 8, 9 



Sand strata — overlaid very generally, by the Yellow Loam deposit 

 previously referred to, which is one of the newest formations of 

 Mississippi. 



7. The thickness of the Orange Sand formation is extremely varia- 

 ble. As originally deposited, its strata appear to have been dependent, 

 as to their thickness, on the degree of denudation which the strata 

 of the more aucient formations had previously undergone ; but at 

 present, the extensive denudations which have taken place in the 

 Orange Sand formation itself have added a complicating element ; 

 so that a most extraordinary capriciousness in this respect, charac- 

 terizes these deposits. The greatest thickness observed with 

 certainty, to my knowledge, was in a well dug at the University of 

 Mississippi, to a depth somewhat more than two hundred feet ; and 

 a section of about the same thickness occurs, according to Prof. 

 Wailes, at the White Cliffs, in Adams county. One hundred feet 

 is no unusual thickness ; but most commonly it varies between 40 

 and 60 feet. Even on different portions of one and the same acre 

 of ground, great variations frequently occur. Thus, in the town 

 of Brandon, wells N. of the R. R. cut reach water at 45 feet, 

 passing through Orange Sand strata all the way ; while S. of the 

 cut, the gray clay of the Upper Lignitic formation is struck after 

 passing through a few feet only of sand. 



8. The existence of hills of more ancient formations within those 

 of the Orange Sand, as exemplified in diagram No. 2, (T39,) is 

 shown in numerous profiles, all over the State ; nor does the exter- 

 nal shape of these ancient hills leave any doubt as to their having 

 been, themselves, originally formed by denudation, and afterwards 

 covered over by the Orange Sand deposits. In such cases, the 

 lines of deposition of the Orange Sand usually exhibit, near 

 to the line of contact, slight inflections, conformable to the 

 curvature of the interior mass ; but the general horizontality of the 

 stratification lines is not thereby disturbed. Nor do I know any 

 instance of the departure from horizontality, in the Orange Sand 

 strata, which could be referred to an upheaval, either local or 

 general. The water obtained within these deposits, never exhibits 

 any tendency to rise. 



9. It is not to be inferred, however, that the stratification of this 

 formation is remarkable for regularity. On the contrary, it is 

 often extremely difficult to trace out one and the same stratum, or 



