ioo REPORT OF THE SPECIAL COMMITTEE 



On the west side of Echo Lake we ascended the prominent bluff 

 next north of the west limestone point, and here found the formation 

 nearly horizontal, but dipping slightly into the hill. The quartzite 

 in this position composes the greater part of the bluff. A short dis- 

 tance from the top we found the quartzite grading upward into a 

 graywacke-like rock, and this into a conglomerate which contains 

 granite and green-schist fragments; indeed, it is typical slate con- 

 glomerate. This conglomerate is only a few feet in thickness, and 

 above it appears a siliceous limestone, and above this, normal lime- 

 stone like that of Garden River and the east side of Echo Lake. 

 The total thickness of the limestone here seen was probably not more 

 than fifty feet, and of the conglomerate below, not more than thirty 

 feet. The lower five hundred feet or more of the bluff is the white 

 quartzite. 



The other bluffs on the west side of the lake were not visited by 

 the party, but Leith, Seaman, and Van Hise have examined each of 

 these bluffs, and found the succession above given to obtain upon 

 each prominent bluff, with the exception that on the next bluff to 

 the north the limestone is wanting, so far as observed. The lime- 

 stone is also in greater force on some of the other bluffs, but is always 

 subordinate in thickness to the quartzite. It thus appears that the 

 great formation on the west side of Echo Lake is the quartzite; that 

 the limestone above appears, not as a single belt, but as a number 

 of synclinal patches often capping the hills; and that the conglom- 

 erate showing both north and south of the limestone is a very thin 

 formation between the quartzite and the limestone, and is, therefore, 

 the lower slate conglomerate. 



Our observations from Root River to Echo Lake convince us 

 that there is a considerable structural break in the Huronian. The 

 upper series includes the following formations of Logan, viz. : white 

 quartzite, chert, and limestone, yellow chert and limestone, white 

 quartzite, red jasper conglomerate, red quartzite, and upper slate 

 conglomerate. The lower series includes the lower limestone of 

 Logan and the lower slate conglomerate, white quartzite, and gray 

 quartzite. North of Thessalon the two series are represented by 

 Logan and Murray as being separated by a fault. Here the dis- 

 tribution may be explained by the unconformity mentioned, but 



