IOWA ACADEMY OF SCIENCES Hfe, 



ON SOME CARBONIFEROUS FOSSILS FROM JACKSON COUNXr, 

 IOWA— [with exhibition of specimens.] 



Br HERBERT OSBORN. 



While on a hasty visit to Jackson county, Iowa, this summer, I was taken, 

 by the kindness of Hon. C. M. Dunbar, to a lime quarry near Monmouth, in 

 the western part of that county, about sixteen miles fromv Maquoketa. 



I found there in the possession of Mr. Stewart, the owner of the quarry 

 and kiln, some fine specimens ©f Lepidodrou and Calamites, which naturally 

 excited ray curiosity (especially as they were so large as to preclude the idea 

 of their having been brought from a distance as specimens), and led me to 

 make special inquiry as to their occurrence. 



Mr. Stewai-t stated that they were found on a hillside near his place, and 

 described the formation in which they occurred as compact sandstone, out- 

 cropping near the top of the hills and extending in isolated outcrops as an 

 open segment of a circle for a distance of about three miles. 



The fossils, which are typical carboniferous forms, are imbedded in a com- 

 pact sandstone. The size of some of the specimens seen, as well as the direct 

 statements of Mr. Stewart, who is well informed on geological subjects, and 

 whose statements may be taken as perfectly reliable, preclude any doubt as 

 to their location. There would be no ground for supposing them erratics 

 and deposited by glacial action, as no carboniferous rocks are known in the 

 direction from which such deposits have come. It seems therefore certain 

 that we have here a limited occurrence of carboniferous strata at a point 

 very distant from the other strata of like age, and indicating a much more 

 extensive area than present strata show. Whether this was actually con- 

 nected with the great carboniferous area, and the intervening portion has 

 been removed by erosion, or whether it represents a small area adjacent to 

 the principal seat of carboniferous deposit, it would be difficult now to con- 

 jecture. It would seem well worth while to make a careful examination of 

 the localiti", and also of all elevated areas intervening between this and the 

 nearest earbonifei'ous outcrops to the south and west. 



