A HdfioiKtl \' icir of Ihc Keireeiid iraii. — W i iiclu'll. 159 
there tra.s a Ioikj erosion inferrttl. It may l)e that the great t'el- 
syte-pebble conglomerate at the mouth of the Montreal river 
will prove yet to be the basal conglomerate of the Keweena- 
wan proper. It is evident that it remains yet to trace out this 
(juartzyte and conglomerate carefully in Wisconsin and Michi- 
gan, as well as in Minnesota, for that they have an important 
place and significance seems unquestionable. It will doubtless 
be found, in the main, along the base of the precipitous side 
of the Keweenawan ridge, in Minnesota on the north side of 
the Keweenawan hills and in Wisconsin on the south side of 
the same range. Owing to the induration which it and the 
overlying sandstone have suffered by the action of the Ke- 
weenawan traps, it is very persistent and has escaped the de- 
struction which otherwise would have befallen it. In volume, 
character and hardness it is comparable to the conglomerate 
and associated quartzyte described by the writer at Cascade, 
Mich., and at Ishpeming.* At the former of these points it 
lies on the Taconic ore horizon of the Animikie and contains 
the peculiar taconyte pebbles, but at the latter it is non-con- 
formable on the lower iron horizon, viz., that of the Vermilion 
range of Minnesota, and is made up locally of the debris of. 
the Archean. The horizon of the conglomerate itself, how- 
ever, is the same at both points, as it is traceable continuously 
between them. It has been supposed to belong in the base of 
the Taconic horizon (Ui)per Huronian) but evidently it is later 
and, according to the foregoing classification, belongs to the 
base of the Keweenawan. Other conglomerates in the region, 
much less dense, though non-conformable on the Taconic iron 
horizon, may belong higher. The mere fact that a conglom- 
erate contains taconyte does not prove it to belong at the base 
of the Keweenawan. It only proves that it cannot be older 
than the base of the Keweenawan. 
There is a curious anomaly to which Van Hise has called 
attention in the Penokee regif>n, viz., the "clun-ty carbonate" 
is intermittent, although it is a part of tlic Penokee series. A 
(•(tnglomeratic qiuirtzyte lies non-conformably upon it. It 
may be that in some places he has mistaken the basal con- 
glomerate of the Keweenawan for a conglomerate of the Pen- 
okee series. In case the structural relations do not sufficiently 
♦Sixteenth Minnesota report, pp. 4.3-48, 1887. 
