OF DENIbON UNIVFRSITV ir 



The Huron Group furnishes "all that is requisite to answer the 

 demands of the Portage and Chemung groups. The thickness is, in- 

 deed, considerably reduced; but it must be remembered that all other 

 New York groups traced into Michigan exhibit even a greater attenu- 

 ation than this parallel would imply." 



Enumerating the fossils of the Huron Ciroup in 1870, Prof. Win- 

 chell says: '' Four of the [19] foregoing species I have identified 

 more or less doubtfully with species of the Hamilton group." "The 

 equivalencies of these rocks are not very precisely indicated from the 

 palasontological data. That the formation is newer than the Genessee 

 shale is demonstrated by its observed superposition. The palasonto- 

 logical evidence indicates, at least, that the fauna is older than that of 

 the Marshall group; and this is all that is necessary. If this group of 

 rocks is proven by stratigraphical superposition to be newer than the 

 Genesee, it belongs either to the horizon of the Portage and Chemung, 

 or to that of the Marshall." "The Huron group, above the black 

 shale, must correspond to the Portage and Chemung or to some por- 

 tion of them." 



Rominger, in 1876, writes: " The light-colored greenish, arena- 

 ceous shales on top of the black shale exposed along the shore of liig 

 Traverse bay, may be possibly an equivalent of the Erie shales of the 

 Ohio geologists, but no fossils have been found by which this (juestion 

 can be determined. The shales in the southern part ot the j)eninsula, 

 which were considered by Winchell, as a part of his Huron shales oc- 

 cupy a higher position, and must be identified with the Waverly." 

 "The conformity of rock material and stratification m this part of the 

 formation, above and below the imaginary division line between the 

 Devonian and carboniferous deposits is .so perfect that no one would 

 accept this stratum as the terminal deposit of the Devonian ocean, 

 even if the fact were ignored that at least 500 f^^et of rock beds below 

 this horizon present the faunal characters of the Cuyahoga shales of 

 Ohio, which form the uj)per division of the Waverly group.'' The 

 order of sequence as given by Winchell, Rominger declares entirely 

 wrong, claiming that it was based upon a mistake of a synclinical sec- 

 tion for a regularly descending one, so that what was regarded by the 

 former as the foot of the section the latter atihrms to be the same hori- 

 zon as that at the opposite extreme. 'I'hese discrepancies are here 

 pointed out not in order to harmoni/e them, which would reiju ire care- 



