220 APPENDIX. 



pieces of limestone, tlie origin of which I will not attempt to 

 assign precisely, though they may have belonged to subordi- 

 nate beds of this rock, that exist somewhere in this forma- 

 tion. I have collected some myself ; others were brought 

 to me by my men ; and, as a notification to future geologists 

 who may travel over this region, I signalize them by their 

 mineralogical characters. 



" 1. A cylindrical limestone, resembling arragonite. 



*' 2. Limestone of loose texture, yellow, crossed by small 

 and numerous veins of calcareous spar. 



" 3. Limestone of a greyish color, with veins of calcareous 

 spar, and invested occasionally by dog-tooth spar. [C. carb. 

 metastastique of Haiiy.] 



" 4. Greyish limestone, with veins of calcareous spar. 



" The inferior members of the group that I have just 

 described contain, it is true, but rare and indistinct organic 

 remains. But no richer field could be ofifered to the fossil 

 conchologist than that presented by the upper portions of the 

 plastic clay — by the variety, the abundance, and the beauty 

 of the specimens, being nearly all new species of ammonites, 

 baculites, belemnites, hipponyx, cytherea, tellina, inoceramus, 

 &c. The species, however, which, from its abundance, and 

 the difi'erent signs under which it is found, would seem to me 

 to characterize the whole formation, is the inoceramus bara- 

 bini of Morton. 



" This cretaceous formation may be considered, I believe, 

 as fairly exhibiting the characteristic features in the geology 

 of the Missouri, over an extent of country more than 400 

 miles in length by water, starting from the mouth of the 

 Sioux River, which latter river is 795 miles from the conflu- 

 ence of the former with the Missisippi, to the approach of the 

 Shayen, which I have laid down on my map as the Washtey, 

 or Good River of the Sioux. It will be readily conceived 



