40 GEOLOGICAL RErORT. [TT70 



32, T. 10 R. 10, E. On the territories of the calcareous (Upper and 

 Middle) stages of the cretaceous, as well as of the tertiary formation, 

 clays suitable for pottery are very rare or entirely absent. The 

 calcareous clay marls often greatly resemble potter's clay, but may 

 he distinguished by their effervescence with vinegar. They are 

 too fusible to serve any purpose of this kind in their natural condi- 

 tion, and they do not appear to have entered to any great extent 

 into the materials of the Orange Sand ; which, moreover, is but 

 feebly developed in their region of occurrence. 



70. On the territory of the Southern Lignitic Tertiary, or Grand 

 Gulf Group, strata of plastic clay also intervene with frequency 

 between the Orange Sand and the undisturbed clays of the lower 

 formation, while considerable deposits of pipeclay entirely within 

 the Orange Sand are on the whole less common than in N. Mississippi. 

 Their layers and nodules (or "pebbles") of pink and purple clay 

 are of very common occurrence in Wilkinson, Amite, Franklin, 

 Pike, Lawrence, Covington, Marion and Perry, and occur more or 

 less over the whole territory of the Southern Lignitic ; but I am 

 not acquainted with any extensive continuous deposits of this 

 character ; they are usually met with in wells just before water is 

 struck, and when penetrated, the lignitic clays are commonly 

 reached at no great distance. 



The pale pink varieties often become of a lighter tint when burnt, 

 and are very refractory ; such is the case, for instance, with the 

 variegated (pink and white) clay occurring at Mr. Wesley Gray's 

 mill on Bouie Creek, near Mt. Cannel, Covington county, which 

 would make good fire-brick. The darker colored varieties, how- 

 ever, become red when heated, and do not resist a high tempera- 

 ture. The intensity of their color is a good indication as to their 

 fusibility. 



At Mr. Bell's, S. 16, T. 7, R. 11 W., Harrison county, .on the 

 Bayou Bernard, there is an outcrop of white and cream colored 

 pipeclay, which is highly refractory and apparently meagre enough 

 to be worked into fire-brick without any further addition ; the 

 Bayou would afford a ready means of conveying it to market. 

 Any admixture of the red and yellow materials occurring at the 

 same place, ought to be avoided. 



The gray potter's clays of this southern region will be mentioned 

 in connection with the southern Lignitic formation. 



