PALEOZOIC ROCKS FOUND IN DEEP WELLS 531 



The writer is greatly indebted to Dr. Ulrich for the inspiration 

 which led to this study and for much unpublished information, 

 and to Mr. F. W. DeWolf for opportunity to examine records from 

 Illinois. The nomenclature and correlation of the formations here 

 given is that proposed by Ulrich and the writer takes no responsi- 

 bility for it as a number of features have not yet met with general 

 acceptance. 



"The Paleontology of the Niagaran Limestone in the Chicago Area: the Trilobita," 

 Chicago Acad. Sci. Nat. Hist. Survey Bull. 4, 1907, Pt. 2, pp. 161-281; "The pre- 

 Richmond Unconformity in the Mississippi VaUey," Jour. Geol., Vol. XV (1907), pp. 

 519-25. F. W. Sardeson, "The St. Peter Sandstone," Minnesota Acad. Nat. Sci. Bull., 

 Vol. IV (1910), pp. 64-88; "The Fauna of the Magnesian Series," ibid., pp. 92-105. 

 E. O. Ulrich, "Revision of the Paleozoic System," Geol. Soc. Amer. Bull., Vol. XXII 

 (1911), pp. 281-680. C. D. Walcott, "Cambrian Geology and Paleontology," Smith- 

 sonian Misc. Coll., Vol. LII (1914), No. 13, p. 354 (gives section by Ulrich). G. H, 

 Cox, "Lead and Zinc Deposits of Northwestern Illinois," Illinois State Geol. Survey 

 Bull. 21, 1914. R. S. Bassler, "Bibliographic Index of American Ordovician and 

 Silurian Fossils," U.S. Nat. Museum Bull, gs, 1915, Plates 2 and 3. G. H. Cady, 

 "The Structure of the La SaUe Anticline," Illinois State Geol. Survey Bull. 36, (1916), 

 pp. 105-41. T. E. Savage and C. S. Ross, "The Age of the Iron Ore in Eastern Wis- 

 consin," Amer. Jour. Sci., Vol. XLI (1916), pp. 187-93. E. O. Ulrich, "Correlation 

 by Displacements of the Strand-Line and the Function and Proper Use of FossUs in 

 Correlation," Geol. Soc. Amer. Bull, Vol. XXVII (1916), pp. 459-61, 477-78- T. E. 

 Savage, "Alexandrian Rocks of Northeastern Illinois and Eastern Wisconsin," ihid., 

 pp. 305-24. G. H. Cady, "Geology of the La Salle and Hennepin Quadrangles," 

 Illinois State Geol. Survey Bull. 2j, (1917), pp. 55-65; "The New Richmond Sandstone 

 of Northern lUinois" (abstract), Illinois Acad. Sci. Trans., Vol. IX (1917), p. 210. 

 W. C. Alden, "Quaternary Geology of Southeastern Wisconsin," U.S. Geol. Survey 

 Prof. Paper 106, (1918), pp. 71-99. G. H. Cady, " Geology and Mineral Resources of 

 the Hennepin and La Salle Quadrangles," Illinois State Geol. Survey Bull. 37, 1919. 

 W. H. Twenhofel and F. T. Thwaites, "The Paleozoic Section of the Tomah and 

 Sparta Quadrangles, Wisconsin," Jour. Geol., Vol. XXVII (1919), pp. 614-33. E. O. 

 Ulrich "Major Causes of Land and Sea Oscillations," Washington Acad. Sci. Jour., 

 Vol. X (1920), pp. 72, 77; Smithsonian Report for 1920, (1922), pp. 321-38. 



Reference may also be made to the folios of the Geologic Atlas of the United States, 

 Nos. 81, 140, 145, 200, and 201, and to publications dealing with Minnesota, Iowa, 

 and northern Michigan; especially W. H. Norton et al., "Underground Water Resources 

 of Iowa," U.S. Geol. Survey Water-Supply Paper 2QJ, 191 2, and Iowa Geol. Survey, 

 Vol. XXI, 1911; C. W. HaU et al., "Geology and Underground Water of Southeastern 

 Minnesota," U.S. Geol. Survey Water-Supply Paper 256, 191 2; R. A. Smith, "Results 

 of Deep Borings," Michigan Geol. and Biol. Survey Pub. 24, (1916), pp. 214-18, 238-39.- 

 A manuscript report on the Sparta and Tomah quadrangles, Wisconsin, is in the hands 

 of the U.S. Survey, and Dr. Ulrich is preparing a report on the stratigraphy of Wis- 



