SOME DYNAMIC PHENOMENA SHOWN BY THE 



BARABOO OUARTZITE RANGES OF 



CENTRAL WISCONSIN. 



The quartzite ranges of Baraboo extend east and west for 

 about thirty miles, one lying north, and the other, the main 

 range, lying south of the City of Baraboo. The geology of 

 this district is admirably given by the late Professor Irving.^ 

 Not only is the general geology clearly described, but remark- 

 ably accurate descriptions are given of the character of the 

 quartzite, and the phenomena shown by it, considering the fact 

 that the report was written nearly twenty years since. The 

 unconformity existing between the quartzite and the Cambrian 

 was later more fully described.^ The induration of the Baraboo 

 quartzite has been explained as due to the enlargement of the 

 original quartz grains ; and to the deposition of independent 

 interstitial quartz. 3 The present note is based upon recent 

 observations on the East Bluff at Devil's Lake and on the 

 exposures at the Upper Narrows of the Baraboo River. 



The section across the ranges, as given by Irving, is shown 

 by Fig. I. The two ranges together, as thus represented, are 

 less than the north half of a great anticline, the south side of 

 the south range being near its crown. This structure involves a 

 very great thickness of quartzite, and was offered with reserva- 

 tion by Professor Irving. He says: "The hypothesis is not 

 altogether satisfactory. The entire disappearance of the other 

 side of the great arch, as well as the peculiar ways in which the 



'The Baraboo Quartzite Ranges, by R. D. Irving. In Vol. II, Geol. of Wis., pp. 

 504-519. 



^The Classification of the Early Cambrian and pre-Cambrian Formations, R. D. 

 Irving. In 7th Annual Rep., U. S. G. S., pp. 403-408. 



3 Enlargement of Quartz Fragments and Genesis of Quartzites, by R. D. Irving 

 and C. R. Van Hise. In Bull. 8, U. S. G. S., pp. 33, 34. 



347 



