113 



80TAS TOBAL AND GEOLOGICAL FEATURES OF 



NO&THWEST LOUISIANA. 



The geology of northwest Louisiana may be Bammed up in a few 

 words. Tin- Boil in the low grounds bordering on the rn 



creeks and bayous is composed of alluvial deposit. The banks of 

 the water courses and their beds are made up of the crumbling 

 brown loam similar to that of the bluff and bill lands between the 

 Ouachita and Red rivers, are covered with the orange sand deposit 

 of the southern diluvial period. 



The alluvial soil on the east side of the Ouachita, is not derived, 

 as might be supposed, from the sediments left behind by the over- 

 flows of that river, but from the spring and early summer rise of the 

 Mississippi, whose backwaters formerly covered the whole area of 

 country included between the Ouachita and Mississippi rivers. 



The Ouachita river is one of the clearest streams in the Southern 

 ' aters are almost transparent, and on this account it may 

 1 as one of the most beautiful rivers of this State. Its 

 banks are composed of a stiff (.rambling brown clay, which do not 

 cave from below by the undermining of the water, but fall down 

 from above by the disintegration of the clay materials. The west 

 side is almost every where protected against the encroachments of 

 the waters by lofty hills and steep or almost perpendicular banks, 

 which, opposite the Hyneston place in Caldwell parish, rise to the 

 height of from sixty to eighty feet. 



The orange sand deposit consists here as every where else of large 

 areas of sand hills; the sand being of various shades of color, from 

 pure white to orange brown; and of various colored clays, which 

 are mostly of a deep red, on account of the prevalence of iron, in- 

 termixed with it in a comminuted state, or existing in large masses, 

 composed of argillaceous iron stone, ferruginous sandstone, and 

 gravel cemented by oaide of iron into a conglommerate or pudding 

 stone. 



The gravel beds are not fo^siliferous. There are, however, found 

 in them, fragments of silicifled ^ood, but no encrimitic stems or 

 shells changed into silica have been met with, similar to the silici- 

 fossils, which exist in great abundance in the gravel beds of 

 Rapides east of Red river, and other parishes east of the Mississippi 

 river. 



