422 A. C. LANE 



beds beneath the Marshall, the top of the Devonian corresponding 

 to Chemung. Later' his investigations led him to include this Mar- 

 . shall with the Carboniferous, and then he also united the Napoleon 

 andstone with it as Upper Marshall, and finally concluded appar- 

 ently that it was not worth separating but only a lentil. The 

 whole matter is discussed in full in the Huron County report. The 

 Marshall is evidently a case of emergence on the east first, micaceous 

 sandstones becoming more and more abundant, and bands of car- 

 bonate of iron and fossils, while blue shales still persist in layers. 

 At a number of places white sandstones occur and thin beds of what 

 I have called peanut conglomerate, white quartz pebbles with heavy 

 cement of carbonate largely of iron, which weathers brown and gives 

 the color effect of peanut candy. The transition from Coldwater 

 is gradual, and it is not easy to fix the line consistently. In fact there 

 are some paleontological reasons for believing that the whole south- 

 western Marshall may be older than the Huron County. 

 The Huron County section is fullest, as follows: 



Napoleon (Upper Marshall) sandstone 300 300 



Lower Marshall (Original Marshall) 



Hardwood Point shales and sandy flags, fossihferous, "typical Mar- 

 shall" fauna 85 385 



Point Austin sandstone 23 408 



Sandy shale 68 476 



Point Aux Barques sandstone -. . . 18 494 



Shales and flags with Romingerines Julia 41 535 



Grindstones with bands of peanut conglomerate and broken gonia- 



tite shells 25 560 



The southern Marshall is thinner and since it is an emergent for- 

 mation it is easy to assume that this part of the formation emerged 

 sooner and was more eroded, and not so soon covered. The series 

 that came after the emergence should also be less complete and as 

 a matter of fact the Michigan series here lacks gypsum and seems 

 otherwise less complete. 



, But may it not be that not only did emergence but the tendency 

 toward emergence indicated by the sandy facies begin sooner ? There 

 is faunal indication of this. 



I See references in Weeks, Bull, igi, U.S.G.S., 260. But add also Am. Jour. 

 Sci., XXXIII, 352-56, and Proc. Acad. Nat. Sci., XIV, 405-30. 



