PREGLACIAL GRAVELS NEAR BARABOO, WIS. 663 
have been referred, with some doubt, to the Cretaceous. On 
the other hand, its relations are so uncertain as to have led to the 
suggestion that it may represent a remnant of the Oriskany sand- 
stone.? It is clear that if its relations to the underlying strata 
do not preclude its reference either to the Oriskany or to the 
Cretaceous, they do not preclude its reference to the Tertiary. 
Since it is overlain by glacial drift only, it would not seem that 
there is anything in its relations to superior strata to preclude its 
reference to the Oriskany, the Cretaceous, or the Tertiary. 
Similar gravel in Fillmore county is unhesitatingly referred to 
the Cretaceous,3 because of its association with certain clays con- 
taining Cretaceous fossils. 
The topographic relations of the gravel and conglomerate of 
Minnesota here referred to, are the same as those of similar 
deposits in the driftless area of Wisconsin, and the suggestion is 
here renewed that they probably go together, and that they are 
very likely to be correlated with the high-level gravels further 
south. 
Conglomerate which may be found to belong with the gravel 
and conglomerate of Minnesota, Wisconsin, Illinois, and regions 
further south, is known to exist at Rockville, Iowa. This was 
referred to by McGee‘ in 1879, as belonging to the glacial 
series. 
In the Devil’s Lake gravel there is nothing, so far as known, 
to fix its age. It rests unconformably on Algonkian rock, and 
it is evidently preglacial. It contains silicified fossils, which 
seem to have been derived chiefly from the Niagara limestone. 
Internal evidence, therefore, does not prohibit the reference of 
the gravel to any period between the Niagara and the Pleistocene. 
If this gravel is to be correlated with the gravels of southern 
Illinois, it is doubtless late Tertiary. On the other hand, there 
is no inherent evidence which precludes its reference to the Cre- 
*Final Report Geol. and Nat. Hist. Sury. of Minn., Vol. L., pp. 305-309. 
"Loc. cit., pp. 355-6. 
3 Loc. cit., pp. 307-11. 
4Geological Magazine, Vol. VI, 1879, p. 360-1. 
