154 



GEOLOGICAL REPORT. 



[12'17, 248 



(Sec. 36.) 

 SECTION OF BLUFF AT DWYER'S FERRY, JACKSON COUNTY. 



This is the last outcrop observed in this direction, bearing the character of the 

 Grand Gulf Group. 



NEWER TERTIARY? OF THE COAST. 



217. It has been mentioned, when speaking of the Orange Sand 

 Group, that its characteristic strata extend, in several points, to 

 within a few miles'of the Gulf Coast. It overlies there a forma- 

 tion partly marine, partly fresh-water, consisting chiefly of gray or 

 black, fetid, ill stratified, massy clay, which forms the impervious 

 stratum to which the "Pine Meadows" of the coast region owe 

 their peculiar features (see "Sea Coast Counties"), and extends 

 seaward into the Mississippi Sound, where it constitutes the ''blue 

 clay bottom" of the deeper channels, beyond the sands of the 

 beach. It is readied at moderate depths along the whole coast, 

 and renders the water of wells uudrinkable, whenever it comes in 

 contact with the "black mud." Notwithstanding that at Pass 

 Christian, for instance, the stratum is reached at 7 feet, it is but 

 rarely so exposed as to afford good opportunities for observation, 

 and the brief space of time which 1 have spent on the coast, has 

 not allowed me to search for them systematically. I shall simply 

 give, therefore, the data I have thus far succeeded in obtaining, 

 without attempting to fix the precise epoch which these strata may 

 represent. 



248. On the Rayon Bernard, near Mr. Bell's, on S. 15, T. 7, R. 11 W., there 

 is an outcrop some 300 yards long, of about 8 feet of dark, bluish-black clay, 

 which is very tenacious, fetid, and irregularly stratified. In this there occurs a 

 lenticular mass, about 10 yards long and 2 to 2y 2 feet thick, of white shells 

 imbedded in clay sinvlar to that which surrounds it. These shells are very 

 much decayed ; we can nevertheless recognize the common living oyster, O. 

 Virginica, which forms their main mass ; adhering to the oysters, we find 

 occas'onal.y the common Bahmus (Barnacle) of the Coast, together with Mytilus 

 hamatas, which at present, also, is generally found clinging lo the oyster. No 

 signa of other fossils were found in the clay surrounding the shelly mass. 



