1102] 



OUTCROPS OP THE EUTAW CROUP. 



63 



clays form the water-shedding strata of the region ; they are. 

 therefore, frequently struck in wells, and numerous springs running 

 off from their surface, have their basins dug into them by the 

 inhabitants. 



102. In Tishomingo county the cretaceous clay is most character- 

 istically developed near the eastern edge of the region, and in many 

 localities overlies the carboniferous rocks, on which we occasionally 

 find its outliers for 8 to 10 miles eastward. The section at Mc- 

 Dougias' mill (1F87) shows the position of this clay with reference 

 to the carboniferous formation ; near Bay Spring (Grisholm's 

 Factory) and in several localities N., E. and S. of the same, it 

 overlies the carboniferous sandstone. Its laminae, in these locali- 

 ties, are usually separated by thin layers of sand, or, more rarely, 

 of mica. The sandy ingredient increases as we advance westward 

 (therefore towards higher strata) and northward from the line 

 between TT. 4 and 3 ; and near to the line of the Tombigbee Sand 

 Group, we more commonly find yellowish or gray sands with but 

 here and there a lamina, streak or lenticular mass of dark colored 

 clay. Diagram No. 4 is a specimen of the stratification usually 

 exhibited in these cases, from an outcrop on the heads of Little 

 Browns Creek, Tishomingo^county. 



Stratification of the Eutaio Group. 



a, greenish-yellow sand. 



b, blue and gray laminated clay. 



These yellow and gray sands, which eventually become micaceous 

 and calcareous, form the transition into the fossiliferous Tombigbee 

 Sand ; still, sands precisely similar are found interstratified with 

 the characteristic Eutasv clays, so that the line 'between the two 

 groups is necessarily somewhat arbitrary. 



