98 R. Irving—Age of the Quartzites, Schists, etc. 
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iferous nature of the sandstone in places to which we did not 
have time to go. The sandstone is, of course, the Potsdam of — 
the surrounding valleys. Section 2 will serve to give a clear 
idea of the structure of this bluff. 
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SECTION 2.—Through North range at W. Bluff of Baraboo Narrows. A, thick-bedded dark col- | 
ored quartzites, with some talco-siliceous schist; B, siliceous schist; C, horizontal sandstone: — 
BY, Parapoo Valley. 
tween the ridges, and in close proximity to them. 
The occurrence of rounded pebbles of quartzite m the oid : 
glomerate on the north side of the south range. To suppose tis 
conglomerate, which by its fossils is unmistakably Potsdam, © 
and the rounding of the pebbles by beach action, b: ork 
formation of the conglomerate; not to speak of the time ® 4 
