WITH THOSE OF NEW YORK. 285 



boniferous limestone is wanting, its fossils appearing only in a 

 few places in shale and sandstones associated with the coal strata. 



For the greater part of the distance along which this limestone 

 was seen, it is but slightly inclined, often appearing horizontal. 

 The only deviation of importance noticed, is near Herculaneum, 

 on the Mississippi river. At this place there appears to have 

 been an extensive uplift in a northeast and southwest direction, 

 elevating the strata at an angle of thirty degrees ; and from the 

 existence of one or two small islands, seeming, at some remote 

 period, to have obstructed the course of the river. From the shal- 

 low water at this place, the uplift appears to have been of more 

 recent origin than the excavation of the river channel, otherwise 

 there appears no reason why the depth here should not be as great 

 as in other places. 



Along the Mississippi river the common fossils were a large 

 species of Delthyris, with a smooth Orthis or Atrypa, in form like 

 the A. concentrica of the lower rocks, but larger ; these appeared 

 at numerous localities which I had opportunities of examining. 

 Several species of Producti, with the larger valve very much 

 arched, and the upper one concave and slightly wa'inlded, are 

 constant, and good guides for this mass. My friend Dr. Owen 

 has recently figured some of the common forms in the July num- 

 ber of the American Journal of Science. Residing upon this 

 formation, his opportunities of investigation are ample, and we 

 may expect that his zeal will lead to the fuU developemcnt of its 

 interesting organic contents. 



After leaving the carboniferous limestone, near the mouth of 

 Rock river, the coal and associated rocks appear, and beyond this 

 point the lower limestones ; the intermediate rocks not being seen. 

 There is evidently either an abrupt synclinal axis, or fault, which 

 has brought up the lower masses. From want of sufficient time 

 to investigate this point, I was unable to determine the precise 

 cause, or amount of change. The contrast between the two lime- 

 stones thus brought into proximity is very striking ; the gray or 

 ashen color is exchanged for a brown or iron-stained rock, harsh 

 to the touch, and composed of small crystalline grains. The 

 mass rises in broken or detached knobs or pinnacles, presenting 



