56 EDWARD M. SHEPARD 



Sand brought up by springs. — We have noted the character of 

 the water in the sunken lakes and streams — its clearness, purity, 

 and temperature — and that the streams, where sounded, seem to 

 have a hard, sandy bottom, and a general absence of muck. We 

 have further referred to the great volume of pure water that is every- 

 where flowing out of this sunken district, and also to the abundance 

 of game fish which only thrive in pure spring water. That typhoid 

 fever is almost wholly unknown in this district is another fact bear- 

 ing on the purity of its water supply. The people drive a pipe with 

 a strainer 10 or 15 feet into the sand, and obtain an abundance of 

 reasonably pure water, which they pump to the surface. 



A careful study of these streams, especially along the St. Francis, 

 the Little Tyronza and the Big Bay, reveals the fact of the constant 

 escape of water from below through small openings surrounded by 

 little cones of sand. This is noticeable for miles along the St. Francis 

 and in the Big Bay district, especially on the bluff side of the 

 streams. 



Deep-seated water, then, is constantly coming to the surface, 

 bringing with it fine sand from below. It is probable that old fault 

 lines through the clay permit this constant discharge, which must 

 slowly and steadily produce an undermining of the clay layer by the 

 removal of the sand below. A glass of water taken from the springs, 

 though seeming quite clear, will deposit, in a few minutes, a fine film 

 of sand at the bottom. Mixed with the little sand-cones that sur- 

 round the spring outlets are minute particles of lignite, which further 

 indicate the deep source of these waters. 



The soil is generally very thin, especially in the southern part of 

 this district, where the sand deposit is thicker, and the surface sand, 

 for several inches, is destitute of the fine particles of lignite, the 

 absence of which is partly due to the action of surface waters in 

 carrying the lighter particles away. Earthworm castings, however, 

 wherever found, show the presence of the lignite. This sand that 

 is spread over the greater portion of the sunken district, in size of 

 grain, structure, general appearance, and association with lignite, 

 closely resembles the drill samples obtained from the Silicious Clai- 

 borne, or La Grange formation, and justifies the conclusion that it 

 has been thrown up from below. 



