THE SWEETLAND CREEK BEDS 



77 



Synthetodus from the State Quarry fish bed in Johnson county. 

 From the bituminous dark shale, number 6, he identifies a Rhyn- 

 chodus, related to R. excavatus Newb., from the Hamilton in 

 Wisconsin. 



LIST OF FOSSILS IN THE SWEETLAND CREEK BEDS 



Impression of plants. 



Lingula, sp. undet. - Identical with one from the Black Shale 



L. cf melie Hall - - - - Cuyahoga Shale 



Lingula, cf. nuda Hall - - - Hamilton 



Lingula subspatulata M. and W. (?) - Black Shale 



Spathiocaris emersoni Clarke ... - Portage Shale 



Solenocaris strigata Meek (?) - - Black Shale 



Gasteropod 



Ptychtodus calceolus M. and W. Hamilton and State Quarry Beds 



Synthetodus - - - ... State Quarry Beds 



Rhynchodus, cf. excavatus Newb. ----- Hamilton 



Additions will no doubt be made to this list. As it is, it 

 indicates a correlation with the Upper Devonian of New York, 

 and more particularly with the Devonian Black Shale of the 

 interior, which also is regarded as a part of the Upper Devonian. 

 To this shale it shows another resemblance in having the basal 

 layers stony and containing a comparatively high per cent, of 

 calcium phosphate, while the upper part is a black shale. It will 

 be remembered that in Perry and Hickman counties in Tennessee 

 the Black Shale changes downward into the phosphate rock. 1 



This comparison may be better shown in tabular form. 



RELATION OF DARK SHALE TO PHOSPHATE BEARING ROCK IN IOWA 

 AND IN TENNESSEE 

 Iowa 



Bed No. 7 contains 2.01 % of phosphate ) 



1.94% " 

 2.13* " 

 3.18* " 



6.05 % " 



5-43 % " 

 4.86? <• 



> Dark Shale 



Variable beds 

 1 Greenish gray 

 ( pyritiferous 

 rock and 



J 



shale 



Tennessee 



Black Shale con- 

 taining little or 

 no phosphate 



Light gray to blu- 

 ish-black phos- 

 phate rock, with 

 disseminated 

 pyrites 



1 See the Tennessee Phosphates, by C. W. Hayes, Seventeenth Ann. Rep. U. S. 

 Geol. Surv., Part II. 



