114 REPORT OP THE 



so short an interval, from the Napoleon Sandstone below, and 

 the Woodville Sandstone above, that the geographical distribu- 

 tion of this formation has not been very accurately determined, 

 even after a pretty careful survey. 



This sandstone was pierced in the boring for salt at East 

 Saginaw, and its thickness was found to be 105 feet. It cannot 

 be a third of this on the southern border of the basin. 



No fossils, except imperfect Calamites and vegetable traces, 

 have been detected in the Parma Sandstone, but accompanying 

 its outcrop, throughout its whole extent, are found angular 

 fragments of a flinty or cherty sandstone abounding in impres- 

 sions of Sigillarice. Not unlikely these remains belong to the 

 formation in question. They frequently recall the characters 

 of the Ohio Buhrstone. 



The Parma Sandstone occupies the geological position of the 

 Ohio Conglomerate. The occurrence of pebbles at a single 

 locality observed, constitutes a faint physical resemblance, but 

 in other respects the correspondence is rather remote. Unlike 

 -the Ohio Conglomerate, it is separated from the upper Devo- 

 nian rocks by a considerable thickness of calcareous and 

 arenaceous strata. 



16. — Coal Measures. 



The Coal Measures, with the overlying Woodville Sandstone, 

 occupy the whole central area of the Lower Peninsula. The 

 territory covered, embraces the counties of Saginaw, Shiawas- 

 see, Clinton, Ionia, Montcalm, Gratiot, Isabella and Midland, 

 and the greater part of Tuscola, Genesee, Ingham, Eaton and 

 Bay, being nearly thirteen counties, besides considerable por- 

 tions of Livingston, Jackson, and probably other counties on 

 the north. The whole area underlaiu by the coal measures is 

 approximately 187 townships, or 6,100 square miles. Over 

 nearly the whole of this extent of country the measures will be 

 found productive. 



The southern border of the basin reaches prdbably into the 

 township of Blackman, in Jackson county. Beyond this seem 

 to be several detached, outliers in which the measures do not 



