CURRENT PRE-CAMBRIAN LITERATURE 745 
resting with visible contact upon the Basement Complex,and composed 
of material mainly derived from it. South of the Cascade range, 
there are again a number of localities from Secs. By hose Marty) IMs Ie 
26 W, where there are basal conglomerates, the great bowlders again 
being mainly identical with the adjacent granites, gneisses, and schists 
of the Basement Complex. South of Summit Mountain, in the west 
half of Sec. 25, T 47 N, R 27 W, is an exposure of the basal conglom- 
erate. The conglomerate grades downward into a schist which is 
scarcely distinguishable from the Palmer gneiss, with which it is in 
contact. The next contact to the west is in Sec. 28, T 47 N, R 27 W, 
where the phenomena are similar to those south of Summit Mountain. 
At the end of the Republic Trough a conglomerate hangs with visible 
contact upon the flank of the Archean granite, bearing well rounded 
waterworn bowlders from it. 
At the north side of the Lower Marquette series, and near the east 
‘end of the district there is exposed a magnificent basal conglomerate 
about three miles west of Marquette, north of Mud Lake. The next 
contacts to the west are at the base of the quartzite east and west of Teal 
Lake. At one place here the relations are such that the layers of the 
conglomerate cut across the foliation of the subjacent schists at an 
acute angle. Still farther west, in Sec. 30, T 48 N, R 28 W, contacts 
are found in a number of places. West of this point the only actual 
contact known is north of the Michigamme mine. 
The unconformity between the Lower Marquette and Upper Mar- 
quette series is also well marked. At the close of Lower Marquette 
time the land was raised above the sea, gently folded and eroded, and 
the Upper Marquette sediments were later laid down unconformably 
upon this floor. In general the discordance between the Lower Mar- 
quette series and the succeeding series is not great, being measured 
frequently by five to ten degrees, at other times by ten to fifteen 
degrees, and it is only rarely that the plications of the lower series are 
such as to make the beds abut perpendicularly against those of the 
overlying series. Erosion has cut deeper in the Lower Marquette 
series in some places than in others, so that the Upper Marquette 
series rests upon different members of the lower series. At the east 
end of the area it left a very considerable thickness of the iron-bearing 
formation, but in places to the west this formation is quite cut out. 
Indeed, in places erosion cut through the Siamo slate and the Ajibik 
quartzite, and in some places even into the Basement Complex. This 
