xil THE PALEONTOLOGY OF MINNESOTA. 



as more recent than the Coal Measures, probably the equivalent of the limestone above 

 the coal fields of Wheeling and Zanesville, W. Va. , and after considerable discussion he 

 places them as the American equivalents of the Lias of Europe; this conclusion is reached 

 mainly from a consideration of the similarity of the lithology of the two limestone forma 

 tions to the limestones of the Lias. In a detailed section at Ft. Snelling (pp. 319-320) he 

 describes an upper limestone formation, which lies on a friable sandstone, which in turn is 

 underlaid by another formation of limestone.* He consideres these strata as similar to 

 those mentioned above as occurring in southern Wisconsin. At Ft. Snelling 'the first 

 stratum which is observed is about eight feet thick; it is formed of limestone, and presents 

 a very distinct slaty structure. The texture of the rock is compact, its fracture splintery 

 and uneven; organic remains abound in it. These are, as far as we saw, exclusively 

 Producti ; they lie in the rock as thick as possible; a small vacant space is generally ob- 

 served between the inner and outer casts of the shell." 



Sir John Franklin. 

 (Second Overland Journey.) 



1825. Narrative of a second expedition to the shores of the Polar sea, by JOHN FRANK- 

 LIN, Capt. R. N., F. R. S., etc. London, 1829. 



"Professor Jameson enumerates Terebratulce, Orthoceratites, Encrinites, Caryophyllitce, and Lingulae, 

 as the organic remains in the specimens brought home by captain Franklin on his first expedition. Mr. 

 Stokes and Mr. James De Carle Sowerby have examined those which we procured on the last expedition, 

 and found amongst them terebratulites, spirifers, maclurites and corallines. 



" The maclurites belonging to the same species' with specimens from lakes Erie and Huron, and also 

 from Igloolik, are perhaps referrible to the Maclurea magna of Le Sueur. 



"Mr. Sowerby determined a shell occurring in great abundance in the strata at Cumberland House, 

 about one hundred and twenty miles to the westward of lake Winnipeg, to be the Pentamerus aylesfordii." 



This is perhaps the species since described from that region by Whiteaves as Penta- 

 merus decussatus. 



G. W. Featherstonhaugh. 



1835. Report of a geological reconnaissance made in 1835, from the seat of Government, by 

 way of Green bay and the Wisconsin territory, to the Coteau de Prairie, an elevated ridge divid- 

 ing the Missouri from tlie St. Peter's river, by G. W. FEATHERSTONHAUGH, U. S. Geologist. 

 Senate Doc. 333; Washington, 1836, pp. 1-168. 



The route taken was from Green bay along the Fox and Wisconsin rivers to the 

 Mississippi, then up the latter stream to Fort Snelling and from there up the Minnesota 

 to its head waters. The geology of the route is very rarely spoken of. The author 

 considered the strata of the entire region, from Green bay west to the Cottonwood river 

 and south to the mouth of the Des Moines, as made up of beds of blue and gray limestone 

 underlaid by a friable sandstone. He refers both of these to the Carboniferous. In the 

 description of Fort Snelling, he says: 



"The fort is built upon the bluff, which overlooks both the Mississippi and the St. Peter's, resting 

 upon grayish buff-colored, fossiliferous beds of the Carboniferous limestone, containing zoophytes, many 



'Tills lowar Iiiu3itoa3 does not exist at Ft. Snelliug; what Keating called the lower limestone is uothiug but the 

 detaclnd fragments of Mie limestone from above the sandstone, which fragments now lie In the river bed many feet below 

 their original position. 



