172 Cmcinnati Society of J^afural History. 



In 1875, he described,* from the Ripley Group at Snow Hill, Greene 

 county, North Carolina, Anomia linifera^Badula oxypleura, Trigonarca 

 triquetra, T. umhonata^ T. perovalis.^ T. caroUnensis, T. congesfa, Ne- 

 modon hrevifrons^ Barhatia caroUnensis, BAintea, Arcoperna caroUn- 

 ensis^ Inoperna caroUnensis^ Mytilus condecoratus, M. nasutus, Etea 

 caroUnensis., Bracliymeris aUa, Crassatella caroUnensis, C. x>teropsis, 

 Arene caroUnensis, Lucina glebula, Cardium caroUnense, Protocardia 

 caroUnensis, Aphrodinaregia,Cyclothyris aUa, C. caroUnensis, Bar o da 

 caroUnensis, Oene plana, Linearia caroUnensis, Valeda Untea, Cypri- 

 meria depressa, Hercodon elUpticus, CymeUa hella, Corhula caro- 

 Unensis, C. hisulcata,C. perbrevis,C. suhgihbosa, Diploconcha cretacea, 

 Callonema caroUnense, Leioderma thoracica., LunaUa caroUnensis, 

 and from Cape Fear river, Corhula oxynema, and Anomia Untea. 



The Cretaceous rqcks,f corresponding in age with the great chalk 

 formations of Europe, though ver3^ different from them in mineral 

 character, are spread over a great extent of surface in the western part 

 of British America. Except in a few localities, and those chiefl}^ in 

 proximity to the Rock}^ Mountain region of uplift, the}' are still 

 almost as perfectly horizontal as when first deposited. The eastern 

 edge overlaps Silurian and Devonian beds, and runs nearl}^ parallel 

 with the base of. the Laurentian range for a distance of about 130 

 miles, from the 53d to the 55th parallel of latitude. Southward it trends 

 to the East, and probably crosses the 49th parallel east of Red river; 

 while in southwestern Minnesota it reposes in some places directly 

 on granites which are no doubt Laurentian. The general course of 

 the eastern outcrop is consequent!}' about north-northeast; and it is 

 marked, broadly, b}' a series of escarpments and elevations, including 

 — from south to north — Pembina, Duck, Porcupine and Basquia 

 Mountains. All these appear to be composed, for the most part, if 

 not entirely, of Ci-etaceous rocks, though the extreme edge of the 

 formation may often stretch beyond them. These mountains are, more 

 correctly speaking, the salient points of the edge of the second plateau, 

 and the geuerall}' horizontal position of the beds thus suddenly cut 

 off to the east, attests the immense denudation which must have taken 

 place in modern times. North of the Basquia Mountain the edge of 

 the Cretaceous would appear to run westward and cross the Sas- 

 katchewan near Fort a la Corne, where, at Cole's Falls, a dark-colored 

 shale has been referred to the lowest member of the series. The 



*Geo. of N. Carolina, 1875. 



t Dawson's Rep. Geo., 49th Parallel, 1875. 



