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MUSEUM OF COMPARATIVE ZOOLOGY. 



63 



As we differ so strikingly in most particulars from the geologists 

 quoted, it is necessary to give our reasons therefor. Only part of a day 

 could be spent at Presque Isle ; therefore, many things that ought to 

 have been examined could not be. On the southeastern side, the sand- 

 stone dips quite irregularly from twenty to thirty degrees southerly. The 

 strata follow the curve of the underlying peridotite, fonuing in places 

 anticlinals. The distinction between the sandstone and its underlying 

 rock was everywhere seen by us to be well marked. The surface of the 

 peridotite is in rounded knobs, the whole mass itself in general outline 

 forming one iunncnsc knob. The sandstone and conglomerate were ex- 

 amined, and found to conform in their stratification to the contour of the 

 whole mass, having the same waving outline; also, for from two to three 

 feet above the peridotite, they are indurated, changed, and show charac- 

 ters that we regard as evidence of heat action and of hot waters. They 

 arc filled with vein and chalccdonic quartz, and hardened and reddened 

 the same as is the sandstone immediately underlying the melaphyr over- 

 flows in the Copper district (75, 76, 77, 78, 79). Certain portions have been 

 changed, so that they resemble a volcanic ash, although they are simple 

 ferruginous sandstones (78). Above the limit of baked sandstone and con- 

 glomerate comes the unaltered ordinary red sandstone (81). Microscopic 

 sections of the indurated conglomeritic sandstone show that much of the 

 quartz is a secondary water deposit since the deposition of the fragments 

 composing the rock. We searched carefully for the pebbles or fragments 

 of the underlying rock in the conglomerate, which Dr. Rominger states 

 are abundant, but could find none. We have been unable to find cither 

 macroscopically or microscopically a single trace, so fiir, of the peridotite 

 or of its veined portion (doUanite of Rominger) in the conglomerate or 

 sandstone. The peridotite forms abundant pebbles now upon the beach, 

 which, had the conglomerate been formed upon it, should have been 

 included. The conglomerate and sandstone contain the same material 

 in pebbles, etc. that the' sandstone and conglomerate do in the Mar- 

 quette quarries and near Carp Rivor. Had the sandstone and conglom- 

 erate been laid down upon the irregular surface of the peridotite, they 

 should have abutted against its unconformable portions, the same as 

 they do against the quartzite at Carp River; instead of this, the strata 

 conform to the curves of the peridotite, like layers of blankets, forming 

 anticlinals and synclinals. The dip in many places, especially on the 

 southeastern side, is too steep and irregular, while the strata are con- 

 tinuous, to have been formed at that angle by sedimentation. The 

 induration of the sandstone and conglomerate, and of the enclosed peb- 



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