20 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 76. 



shells. The first continuous layer of the Petoskey series is a non- 

 bcdded, dirty, fragmental limestone with Gypidulas followed by a 

 fossiliferous sand rock. The same upper member of the Charlevoix 

 (bed 9) is again seen in irregular contact with the lowest Petoskey 

 farther west at the junction of State Highway No. 11 and the 

 Walloon Lake Road (south extreme of section line between sees.. 

 1 and 2, T. 34 N., R, 6 W., Emmet County, locality 16), where con- 

 ditions similar to those just described for locality 15 are to be 

 observed. 



At the beginning of Petoskey time conditions Avere still very un- 

 stable, as is evidenced in the lateral variation of single beds, in the 

 overlap by others, and in general by a series of fragmental limestones 

 at the base. There is, moreover, in a certain fragmental, crinoidal 

 coquina excellent indication of shallow water conditions in the 

 foreset, cross-bedded bedding planes near the base of the section. 

 Through the lower 30 or so feet of the Petoskey series are continuing 

 indications of sedimentation within the range of current or wave 

 action. This is especially to be seen in the fragmentary character 

 of the abundant reef -forming Stromatopora heads, which more often 

 than not lie disconnectedly and in abnormal position in the frag- 

 mental matrix of calcareous sand. These have in most cases been 

 violently broken away from their original connections and distrib- 

 uted at varying distances from them. The middle of the section 

 again shows in its compact and evenly bedded, fine grained lime- 

 stones and shales a return to normal and steady marine deposition in 

 the area. The introduction in the upper portion of the section of 

 an abundance of colloidal silica in the form of segregated and banded 

 chert argues strongly for a return of the area to a condition which 

 was affected by shore influences and a mingling of land waters carry- 

 ing silica in suspension with the saline waters of the epeiric sea. 

 This is further emphasized by the occurrence of dolomite in these 

 beds, for it is a known fact that calcium and particularly magnesium 

 are especially effective in the precipitation of colloidal silica. The 

 necessary carbon dioxide was of course produced by the presence of 

 abundant invertebrate life. 



At the present time the actual contact between the Traverse and 

 the succeeding black shale has not been seen so that the physical 

 conditions of juxtaposition may not be remarked upon. 



FAUNAL INDICES OF THE STEATIGRAPHIC UMTS 



The present status of paleontologic knowledge of the Traverse 

 will for some time necessitate the use of rather broad and general- 

 ized statements. By far the greater majority of the organic remains 

 preserved in these strata is still undescribecl, and those already 

 described and identified have not been sufficiently compared for 



