AND THE SALT D K ]' O S I T ON PETITE A N S E ISLAND. 23 



of its formation with that of the Port Hudson bkiff ; inchiding even (at the proper 

 level) the characteristic calcareo-ferriiginous nodules. 



West of the Mississippi we have, opposite Port Iliidson, where the Cote Gclee 

 and the Grand Coteau dcs Opelousas abut upon the Bayou Cocodrie, outcrops, and 

 profiles, in wells, correspondinjj^ closely to that of Port Hudson; especially as regards 

 the blue clay with stumps and trunks of trees, near low-water level. 



Few outcrops or well profiles in the Opelousas and Attakapas prairies, from 

 bayou Cocodrie to the Calcasieu river, reach below wliat are doubtless the 

 equivalents of the upper portion of the Port Hudson bluft', viz. gray, yellow, or 

 mottled siliceous silts or loams ; beneath which, at depths varying from ten to 

 twenty feet, water, mostly very hard from carbonate of lime, and frequently tinged 

 and flavored with vegetable matter, is obtained. The dead uniformity in the con- 

 formation of the whole prairie region, can leave no doubt as to the continuity of 

 the underlying formation; whose clay members approach nearer the surface as we 

 advance westward and coast-ward, preventing the percolation of the atmospheric 

 waters, and thus causing the wet glades and prairies that have, to a most unwar- 

 rantable degree, impressed themselves upon almost all the maps of Calcasieu and 

 the western coast of Louisiana. In reality, neither canoes nor mudstilts would be 

 of any special use in the Calcasieu prairie, away from the heads of streams; the 

 wide belts of marsh represented as flanking tlie latter on their course to the sea 

 being, as a rule, neither better nor Averse than other river bottoms in the Gulf 

 States usually are. 



Near the latitude of Lake Charles, the soil of the Calcasieu prairie is directly 

 derived from the stifl" clay with calcareous nodules, tliat crops out in tlie beds of 

 streams; it resembles closely the more clayey strata at C6te Blanche and Weeks' 

 Island, while on Lake Charles, near the town of that name, tliere are outcrops of 

 the reddish silt and loam which forms a conspicuous feature in the Cote Blanche 

 profile. Wells at Lake Charles strike these materials, and not unfrequently also 

 the common oyster of the coast, as well as logs — precisely as is the case farther 

 east ; on Bayou Sale, at Bonnet Carre, New Orleans, and on tlie Mississippi coast ; 

 and showing, here as there, an increase of the marine facies as we approach the 

 coast. 



The thickness of the formation is shown in the bores made for petroleum and 

 sulpliur, near tlie West Fork of Calcasieu river. Having been dei^jositcd on a 

 deeply denuded surface of Drift beds, it varies, within seven hundred yards, from 

 one hundred and sixty to three hundred and fifty-four feet; marine shells having, 

 apparently, been found only in the upper portion. 



The belt of coast prairies continues, with little change of character, into Texas, 

 where the conformation of the coast seems to be almost exactly parallel to tliat 

 prevailing in Mississippi and Alabama ; viz. long sandy islands, ofl" the mainlaiul, 

 on whose beach blue clay with stumps is washed by the surf; while near the heads 

 of the bays, there are bluff" banks exhibiting outcrops of blue or variously tinted 

 clays. Outcrops almost precisely corresponding to those at Cote Blanche and on 

 Lake Charles, have lately been studied by ]\Ir. II. II. Lougliridge, my Assistant, on 

 Lavaca Bay. The occurrence of similar clays on Aransas Bay. and on the Laguna 



