ElvISHA MiTCHELIv SCIENTIFIC SOCIETY. 9 



gioti, especially in Moore and Harnett Counties, there 

 are limited exposures of silicious Kocene deposits (over- 

 lying- the Potomac series, and capping- some of the 

 sand-hillsj which have recently been tested for fire- 

 brick with very satisfactory results. These deposits 

 are from 5 to 15 or more feet in thickness, and are over- 

 laid b}^ but a few feet of loose sand. The following 

 analysis of this material, collected two miles N. E. of 

 Spout Si)rings," shows its general composition. 



ANALYSIS OF "fire-clay" ( EOCENE) TWO MILES N. E. OF SPOUT 

 SPRINGS, N. C. 



Silica 87.70 



Alumina 3,29 



Ferric oxide 2,81 



Lime 0.48 



Magnesia 0,40 



Alkaline chlorides 1.48 



Loss on ignition 3.15 



Total 99.31 



Among the Miocene deposits, there are, in places 

 along- the river-bluffs of the Coastal Plain region, es- 

 pecialh^ on the Roanoke and the Tar, somewhat exten- 

 sive exposures of "blue marl," a calcareous clay ^vhich 

 may prove to be of some value, but of which no prac- 

 tical tests have yet been made- 



The Lafayette (Pliocene; materials, which are spread 

 over so large a portion of the Coastal Plain region, are 

 g-enerally gravell}^ or sandy in composition, with a 

 large admixture of loam in many places. No extensive 

 deposits of clay have been observed among- the mate- 

 rials of this formation, though doubtless limited depos- 

 its of cla}^ will be discovered as more extensive explo- 

 rations are made. 



^ Made in the laboratory of the N. C. Geological Survey. 



