BULLETIN OF THE UNIVERSITY OF WISCONSIN 

 Science Series, Vol. i, No. 2, pp. 35-56, pls. 1-3, January, 1895 



ON THE QUARTZ KERATOPHYRE AND ASSOCIATED 



ROCKS OP THE NORTH RANGE OF 



THE BARABOO BLUFFS.' 



BY SAMUEL WEIDMAN." 



CON TENTS. 



I. Introduction. 



II. Field Geology. 



Limestone. 



Sandstone and conglomerate. 



Quartzite. 



Quartz keratophyre eruption: its areal extent, 

 contact, absence of bedding. 



Types of the quartz keratophyre: quartz kerato- 

 phyre, sericite schist, volcanic breccia. 



Conclusions from field study. 



III. Microscoi)ic Geology. 



Feldspar phenocrysts, quartz phenocrysts, ac- 

 cessory minerals. 



Groundmass: fluxion, poikilitic, and spherulitic 

 structures. 



General conclusions. 



In the south central part of Wisconsin, extending across 

 the middle portions of the county of Sauk and for a short 

 distance into that of Columbia, there arises above the surface 

 of the surrounding area two long ranges of hills or ridges. 

 These ranges trend across the country in an east and west 



1 A thesis submitted for the degree of Bachelor of Science in the Geology Group of the 

 General Science Course, University of Wisconsin, June, 1894. Read before the Geological 

 Society of America at the Baltimore meeting, December, 1894. 



2 This paper is the result of work undertaken and executed under the du-ection of Pro- 

 fessors W. H. Hobbs and C. R. Van Hise. To the former I desire to express my thanks 

 for superintending the work in the laboratory, for preparing the photo-micrographs, and 

 for other valuable help, and to the latter for giving me aid and suggestions in the field 

 study. I also desire to express my obligation to Mr. C. F. Austin who kindly furnished 

 the chemical analysis for this paper. 



