ART. 14 MICHIGAN TRAVERSE GROUP POHL 25 



well. The succession varies in development between 669 and 670 feet 

 of actual and estimated thickness in the two following wells : Boyne 

 City, Northwestern Michigan Development Co., J. M. Stutzman well 

 No. 1, located in the SE. 14 of NW. i/4 of sec. 16, T. 33 N., R. 6. W., 

 Evangeline Township, Charlevoix County ; and the Petoskey munici- 

 pal well, located near the city waterworks in the bottom of Bear 

 River " gorge " a short distance from Little Traverse Bay, Petoskey, 

 Emmet County. 



LAKE HURON SEQUENCE 



A restudy of the eastern Michigan Traverse has been undertaken 

 by the geological survey of the State, but further details of this suc- 

 cession must await the completion of field studies. Until recently the 

 sections have remained as they were described by Grabau in 1901,^* 

 with the exception of a discussion of Grabau's newly proposed 

 Presque Isle series. ^^ 



Before proceeding to a faunal comparison of the sections exposed 

 in the western and eastern portions of Michigan a brief summary of 

 the existing stratigraphic knowledge of the latter area is appropriate. 



The fourfold subdivision previously adopted for the Traverse 

 group in Presque Isle and Alpena Counties has more recently been 

 restricted by Grabau, the Bell Shales now forming the lowest member 

 of the Presque Isle series. The sequence in downward succession as 

 now understood is as follows.^® 



Feet 

 Thunder Baj' series (stage) 137-190 



Alpena series (stage) 118-134 



Presque Isle series (stage) : 



Long Lake beds (member) 157-169 



Grand Lake limestone (member) 39- 39 



Bell Shales (member) 60- 80 



Total Traverse group 511-612 



The contact phenomena of the various stages of the thus sub- 

 divided Traverse group in eastern Michigan have not so far under- 

 gone close study, but widely different lithic and petrographic charac- 

 ters are found by rock analysis to be constant through each of the 

 divisions. A tabulation of the available analyses will show the per- 

 centage range of the major constituents of samples taken from 

 various portions of the succession. 



" Grabau, A. W. Mich. Geol. Surv. Ann. Rept. for 1901, pp. 175-196, 1902. 

 IB Grabau, A. W. Unpublished manuscript, pp. 290-308, 1915. 



^« Grabau, A. W. Unpublished manuscript, pp. 298, 308, 318, 441, 1915. Notes of 

 Mich. Geol. Surv. Expedition, 1926. 



