532 TIIK MARQUEITE IIJOX-BEAIUNG DISTRICT. 



pianos. As till' Darallel l)an(Iiiii>' is coniincd to this oiu' direction, it is certain 

 that (luring- its developuient no other system of jjaralk'l phmes existed iutlie 

 rock. The last se\-ere folding, which has determined the larger structural 

 features of the ^[arquette district, has also affected the rocks in a more inti- 

 mate wav. In certain localities strong minor, even minute, crenulations 

 have been i)ro(luced, and also parallel cleavage, which sometimes traverses 

 the banding of the rock at right angles. The little folds are often broken 

 and faulted and the siliceous bands reduced to fragments. Along the 

 parallel cleavage planes mo^■ement has often taken place, as is shown by 

 the displacement of a particular band on the two sides. Along this sec- 

 c>ndar>' cleavage, whicli dates from the j)eriod of general folding after 

 Upi)er Marquette time, no great development of new minerals, except the 

 iron oxides, has taken place, while the displacement which the minute 

 faulting has caused in the lianding conclusively proves that this structure 

 was present before the folding. 



From these various lines of evidence, from the apparently definite 

 stratigraphical ])Osition of the two main varieties of the iron-bearing member, 

 from the presence in the upper conglomei-ate of pebbles of all the various 

 kinds of i-ock which are now found in the iron-bearing member, and from 

 the mechanical eflects which the last folding has produced in the banded 

 structure, it seems beyond question that the iron-bearing formation had 

 essentially its present character at the time when the Upper Mar(j[uette series 

 was laid down. 



CONTACTS BETWEEN THE LOWER MARQUETTE SERIES AND THE ARCHEAN. 



It has alreadv been said that the Ajiliik (piartzite lias been foand in 

 only a few places. The contact between this rock and the Archean is 

 almost everywhere drift-covered, and actual juxtaposition has been found 

 in but two localities. The i-vidence at one of these as to the relations 

 between the two series is very clear and convincing. 



In the eastern part of the NW. ] of the NE. \ sec. 18, T. 46 N., R. 29 W. 

 (Atlas Sheet XI), is a large outcrop of the (piartzite, which was discov- 

 ered bv Pumpellv and Credner in ISfiT. The locality is at the extreme 

 southern end of the Rejjublic syncline. A short distance southwest of the 



