12 GEOLOGICAL REPORT. IMS, 19 



alluvium of the Mississippi River, occupying, in N. Mississippi, parts 

 of the counties of De Soto, Panola, Yallobusha, Carroll, Holmes, 

 and Yazoo, gradually diminishing as the territory of the fossiliferous 

 eocene is approached, and giving out almost entirely in the greater 

 portion of Warren county. Then, below Vicksburg, it extends 

 inland in a S. E. direction, and is found in numerous cuts on the 

 New Orleans, Jackson and Great Northern Railroad, down to the 

 Louisiana line. It appears in greatest force W. of the dividing- 

 ridge, and is but thinly represented on Pearl River ; on the waters 

 of the Bogue Chitto, however, it advances eastward, appears at 

 Holmesville, and to a limited extent, in Marion county, on Pearl 

 River. Westward of the dividing ridge, it is frequently met with 

 until we reach the territory of the Bluff formation, where it is 

 generally covered by the materials of the latter ; as it is elsewhere 

 by the yellow surface loam. 



18. The other region of occurrence of the pebble bed, begins at 

 the N., on the Tennessee River, in E. Tishomingo, and extends 

 along the waters of Big Bear Creek, to the eastern heads 

 of the Tombigbee, reaching the latter stream by way of Hurricane 

 and Bull Mountain Creeks, in Itawamba county. It then extends 

 southward on the eastern side of the Tombigbee, and is continued 

 into Alabama, meeting the great pebble beds of the Warrior, 

 which bear the city of Tuscaloosa. It appears that the pebble 

 beds, as well as the Orange Sand in great force, are found well 

 developed in the northern counties of Alabama. Great masses of 

 pebbles are being moved southward, from these beds, by the 

 Warrior and Tombigbee Rivers, whose navigation they tend to 

 obstruct ; the materials of the more ancient beds, however, as well 

 as of those now being formed by the rivers, become finer as we 

 advance southward, and ultimately mingle, imperceptibly, with the 

 sands of the Coast. (Tuomey.) 



Whether or not the two great belts of pebble deposits are connected with one 

 another, somewhere in W. Tennessee, I have not learned ; but from the 

 direction of their respective outlines, where they leave Mississippi, such a 

 junction seems highly probable. Between the two belts mentioned, pebbles are 

 either absent from the Orange Sand formation, or appear only casually, and of 

 inferior size — as small gravel. Some of the latter, however, as well as, 

 occasionally, a few larger pebbles, properly belong to the yellow surface loam, and 

 usually differ, lithologically, from those of the Orange Sand. 



19. As for the material of the pebbles themselves, it is almost exclusively 



