JS^eic Features in Geology of Jlinnesota. — Winc/iell. 51 
considerations that we reached the tentative conclusion that 
this slaty rock is an upper member of the Animikie not before 
individualized by the survey, nor indeed before mentioned by 
any geologist. It is over this soft, slaty, greenish rock, that 
the Puckwunge conglomerate belongs. 
This conglomerate consists of quartzyte pebbles, for the 
most part, but this quartzyte varies in color from white to 
pink and to red. These are not perfectly characteristic, but 
are referable to the quartzytes that are a large feature of the 
Animikie in the hills next further north. We gathered an 
assortment of these pebbles, and shall make further examina- 
tion of them. We sought in particular for the well-known 
taconyte pebbles, which would show this conglomerate to be 
later than the ores of the Mesabi iron r^ange, hence later than 
the Animikie, and although the specimens have not yet been 
examined microscopically, two or three of them appear to be 
of that peculiar kind of pebbles.* 
The importance of this discovery is also great. It extends 
to a region not before suspected the basal conglomerate of the 
Keweenawan. This conglomerate is known at the base of 
Grand Portage island and more recently we have identified it. 
tentatively, along the lake Superior coast, at intervals, from 
Baptism river to near Beaver bay, and further east. It is a 
valuable guide to the separation of the older Norian eruptives 
from the true Keweenawan. I have recently brought this sub- 
ject out fully in a series of papers in the American Geologist, 
and it is not necessary to dwell on it again. f 
These three important observations and that relating to the 
nature of the contact of the Saganaga granite on the Ogislike 
conglomerate, were the results of a three weeks' trip late last 
fall. They show that it is necessary to proceed very careful- 
ly in drawing general conclusions as to the geological struct- 
ure of that portion of the state. Our work has shown the ge- 
ographic distribution of the formations, but it has not been 
sufHcient to show, in all cases, the chronologic order and the 
genesis of the rocks that we have described. 
*Thin sections have later been examined. They show the peculiar 
crypto-crystalline silica of the rock taconyte, but not the usual amouut 
of iron oxide. They arc referable to the Animikie. 
tA rational view of the Keweenawan. Am. Geol., xvi, 150, 1895. 
