HISTORICAL SKETCH. XXV11 



The fossils of F. 3 are represented in Table n, na and n&. 



In the general table of stratigraphical and geographical distribution of fossils, Dr. 

 Owen represents the lead-bearing beds (For. 3&) as the equivalent of the Utica slate and 

 Hudson River group, and he indicates what fossils of these beds are found in the Utica 

 slate and Hudson River in New York. This is a very meager showing, as might be antici- 

 pated from the fact that the true horizon of the Hudson River group is entirely above the 

 lead-bearing horizon, and between it and his "Coralline and Pentamerus beds." 



In another table, of the equivalency of the formations of the lead region with the 

 New York system, not only does he express the same idea, but shows clearly that he re- 

 garded the Shell-bed (For. 3a) as the representative of the whole of the "Blue limestone" 

 of Ohio, and also makes it embrace the Trenton and Black River limestones, the Birdseye 

 and Chazy having no representative in the upper Mississippi valley. 



It is singular that neither the survey of Foster and Whitney, whose parties visited the 

 lead region and the falls of St. Anthony, nor that of D. D. Owen, whose central and most 

 important area was that covered by the Lower Silurian, in the upper Mississippi valley, 

 detected the Hudson River group in its true position, although they both made some 

 quasi provision for it in their classification. 



Edward Daniels. 



1854. First annual report of the Geological Survey of the state of Wisconsin, by 

 EDWARD DANIELS; Madison, 1854; pp. 1-84. 



This report is devoted chiefly to the economic resources of the lead region. Two 

 geological sections are given, one from Dubuque to the Blue mounds, and the other a 

 vertical generalized section of the rocks of the lead region; the latter is as follows: 



1. Drift; 20 feet. 



2. Coralline beds of Dr. Owen; 300 feet. 



3. Nucula shale; 15 feet. 



4. Gray limestone the lead-bearing rock; 250 feet. 



5. Blue limestone; 40 feet. 



6. Buff-colored limestone; 30 feet. 



7. Sandstone; 60 feet. 



8. Lower Magnesian limestone of Owen; 200 feet. 



The Nucula shale of this section is the Blue shale of J, G. Percival. It is said to be 

 thickest in the lead region and to gradually thin out toward the north and east. The 

 fossils being all of diminutive size, he styles the shale a "fossil Lilliput," analogous to 

 Hugh Miller's "age of dwarfs" among the fishes of the old red sandstone. He does not 

 assign it to any place in the New York system. 



The Blue limestone is considered as "undoubtedly the equivalent of the Blue lime- 

 stone so abundantly developed at Cincinnati." The Buff limestone is below the Blue. 



J. G. Pericival 



1855. Annual report on the Geological Survey of the state of Wisconsin. By JAMES G. 

 PERCIVAL; Madison, 1855; pp- 1-101. 



The entire report is given to economic geology and the lead region is the only part of 

 the state described. The series of rocks found here is as follows: 



