114 REPORT OF THE 



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

 the Woodvillc 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 Catamites 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 iu impres- 

 sions of Sigitlarioe. Not unlikely these remains belong to the 

 formation in question. They frequently ropall 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 fa : nt physical resemblance, but 

 in other respects the c wrespendence 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 underlain by the coal measures is 

 approximately 187 townships, or 6,700 square miles. Over 

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

 found productive. 



The southern border of the basin reaches probably into the 

 township of Blackmon, in Jackson county. 3eyond this seem 

 to be several detached outliers in which the measures do not 



