and the Mudlumps of the Mississippi 4:31 



A sample from tlie general mass shows it to consist mainly 

 of very iine quartz sand, mostly angular, with but a few large, 

 angular grains ; and but little true clay. 



In washing the mass, even the first washings were found to 

 contain but little clay, but chiefly very fine suspended silex. 

 A few ill defined spicules, a Navicula, and bark fibers. 



In the middle portion, spicules a little more abundant. 



In the coarsest portion, much variously colored mica, along 

 with, mostly sharply angular, quartz grains ; numerous particles 

 of water-browned wood ; very distinct spine of a radiate ; sev- 

 t-ral specimens of Rotahna, and fragments of same as well as 

 Uvigerina, Cristellaria, Amphistegina, and Coccmeis . Also 

 iridescent fragments, showing lines of growth, from the edges . 

 of larger bivalves. 



Quartz grains mostly transparent and angular; some ot 

 luilkv, oil-green, and rose quartz ; these mostly rounded. Ihis 

 ^an.r resembles closely that of the bottom outside Northeast 

 i';is< l);,r, in 40 to 50 feet water ; specimens of which were fur- 

 Mi^liwl me by the Coast Survey party, under command of Capt. 

 !■'• V. Webber of the schooner Varina, in 1869. 



Specimens from mudlumps on Southwest Pass show coarser 

 sand, and rather more Foraminifera. 



'The character of the materials ejected by the mudlump 

 springs, as determined by the foregoing investigations, may be 

 summed up as follows : . . , 



^ 1. The gas is such as is evolved by vegetable matter in its 

 first stages of decay or lignitization. . . 



2. The earthy matter contains both river and marme fossils-- 

 driftwood reduced almost to its cell- elements by maceration and 

 tnturation, as well as Foraminifera. Its fineness is such that, 

 before final deposition, it may have been carried out into water 

 of considerable depth. " t 



,.3. The mudlump waters appear to be sea-water more or less 

 diluted, and chemically changed under the joint influence o 

 fermenting organic matter, and the more active ingredient, o 

 tiie river deposit, viz: carbonates of lime and magnesia, and 

 oxide of iron. ,,.,. 



The first effect thus produced would probably be the addition 

 of the soluble carbonates of these metals to the solution But 

 ^lie soluble sulphates could not, in the presence of a soluble 

 ifon salt, long resist the reducing influence of decaying organic 

 °^tter. As usual under such circumstances, iron |yrixe^ 

 j;ouldbe formed, withdrawing in the end all the ^ulptur cjicki 

 from the solution, and forming, instead, equivalent amounts of 

 tbe respective carbonates. The amounts of the chlorides ot 

 * See Bischoff, Chemische Geologie, vol. i, p. 559. 



