THE PALEOZOIC SECTION OF THE TOMAH AND 

 SPARTA QUADRANGLES, WISCONSIN' 



W. H. TWENHOFEL and F. T. THWAITES 



University of Wisconsin 



INTRODUCTION 



The Tomah and Sparta quadrangles lie wholly within and on 

 the northeastern edge of the Driftless Area of western Wisconsin. 

 The first-named quadrangle is directly east of the latter. There 

 are 431 square miles in the two areas. 



Little geologic work directly relating to the two quadrangles 

 has been published. As parts of the Driftless Area they have 

 received the attention of many of the students who have been 

 concerned with its pecuHar problems. Three university theses 

 which directly relate to the whole or parts of the two quadrangles 

 have been written, but none of these has been published.^ A short 

 paper by W. D. Shipton gives a description of fulgurites^ found by 

 him near Sparta, and the same author in a second short paper 

 proposed a new formational term for the fine-grained and shaley 

 sandstones which constitute the middle portion of the exposed 

 Cambrian.'' Other papers which in some degree bear on the 

 geology of the two quadrangles are Ulrich's "Revision of the Paleo- 

 zoic Systems, "5 Bassler's ''BibKographic Index of American Ordo- 

 vician and Silurian Fossils,"^ in which is given a geologic section 



' Published by permission of the state geologist of Wisconsin. 



^ R. B. Johns, "The Physiography and Geology of the La Crosse River Valley." 

 Unpublished thesis. University of Wisconsin, 1900. W. D. Shipton, "The Geology 

 of the Sparta Quadrangle." Unpublished thesis, University of Iowa, 1916. W. O. 

 Blanchard, "The 'Geography of the Tomah-Sparta Quadrangles." Unpublished 

 thesis, University of Wisconsin, 191 7. 



^W. D. Shipton, "A Note on Fulgurites from Sparta," Proc. Iowa Acad. Sci., 

 XXIII (1916), 141. 



"•W. D. Shipton, "A New Stratigraphic Horizon in the Cambrian System of 

 Wisconsin," ibid., pp. 142-45. 



s E. O. Ulrich, Bull. Geol. Soc. Amer., XXII (191 1), PI. XXVII. 



' R. S. Bassler, Bull, gz, United States National Museum, II (1915), PI. II. 



614 



