OF DENISON UNIVERSITY 
15 
The H*uron 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 Group 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 
palaeontological data. That the formation is newer than the Genessee 
shale is demonstrated by its observed superposition. The palaeonto- 
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: “ I'he light-colored greenish, arena- 
ceous shales on top of the black shale exposed along the shore of Big 
Traverse bay, may be possibly an equivalent of the Erie shales of the 
Ohio geologists, but no fossils have been found by which this question 
can be determined. The shales in the southern part ot the peninsula, 
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 in 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 feet of rock beds below 
this horizon present the faunal characters of the Cuyahoga shales of 
Ohio, which form the upper 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 affirms to be the same hori- 
zon as that at the opposite extreme. These discrepancies are here 
pointed out not in order to harmonize them, which would require care- 
