Ferruginous Sand Formation. 289 



Arkansas. — Mr. Nuttall describes this formation as occurring ex- 

 tensively on the calcareous platform of the Red river, above and be- 

 low the junction of the Kiamesha ; and Dr. Pitcher has lately ob- 

 tained there some large Ammonites and other fossils which I have 

 not yet received. 



Missouri. — Messrs. Lewis and Clarke, Mr. Nuttall and Col. Long 

 found Baculites, Hamites?, Gryphsese, and other marl fossils at the 

 Great Bend of the Missouri river (Lat. 43° 40' N., Long. 72° W. 

 from Washington) intimating the existence of the ferruginous sand in 

 that remote region of our continent, as mentioned on a former occasion. 



Now these various deposits, though seemingly insulated, are doubt- 

 less continuous, or nearly so, forming an irregular crescent nearly 

 three thousand miles in extent ; and what is very remarkable, there 

 is not only a generic accordance between the fossil shells scattered 

 through this vast tract, but in by far the greater number of compar- 

 isons I have hitherto been able to make, the same species of fossils 

 are found throughout : thus the Ammonites placenta, Baculites ovatus, 

 Gryphcea Vomer, Gryphaa mutabilis, Ostrea falcata, &fc. are found 

 without a shadow of difference, from New Jersey to Louisiana : al- 

 though some species have been found in the latter State, that have 

 not been noticed in the former, and vice versa. 



There seems also to be superposed on the ferruginous sand of the 

 Southern States a calcareous deposit, in mineralogical characters not 

 very unlike that of New Jersey ; but of its organic remains I have 

 seen but few species, consisting of Nummulites, Gryphites, and Pec- 

 tens ; all differing obviously from any others with which I am ac- 

 quainted. The principal deposit of this kind occurs near Claiborne, 

 Alabama. Another, noticed by Mr. Nuttall, near Wilmington, in 

 North Carolina, appears to be a link in the same series. 



In further corroboration of the views maintained in these essays I 

 may add, that Mr. DelaBeche, in his Geological Manual, p. 294, 

 after giving a list of the fossils contained in the former parts of this 

 Synopsis, concludes his observations on the cretaceous group in these 

 words : " It is almost impossible not to be struck, in the foregoing 

 list, with the great zoological resemblance of this ferruginous sand 

 deposit with the cretaceous rocks of Europe. As has been above 

 noticed, the genera Baculites, Scaphites and Turrilites have not been 

 discovered out of this series in Europe. The Pecten quinquecosta- 

 tus is a well known and widely distributed chalk fossil. But it is 

 not so much by individual parts as by the general character of the 



Vol. XXIIL— No. 2. 37 



