DESCRIPTION OF SECTIONS 309 



Section of Strata exposed in the Iron-ore Pit near Neda 



Mayville limestone. Feet 



5. Dolomite, gray, crystalline, vesicular, in layers 1 to 2 feet thick ... 12 



4. Dolomite, yellowish gray. hard, crystalline, in irregular layers .... 24 

 A break in sedimentation. 



Iron-ore bed. 



3. Iron ore, nearly black, impure 1 



2. Iron ore, oolitic, brown to red, in regular layers, with small pebble- 



like masses of iron at certain zones in the lower part 12 to 30 



A break in sedimentation. 

 Maquoketa shale. 



1. Shale, bluish gray, calcareous 8 



The lower part of the Mayville limestone at this place, as elsewhere in 

 'Wisconsin, furnished several fossils which were mostly casts and molds 

 of Zaphrentoid and Favositoid corals, the preservation of which was so 

 poor as to make specific identification too uncertain for purposes of corre- 

 lation. The species that could be satisfactorily identified have a wide, 

 vertical range and are not markers of any definite horizon in the early 

 Silurian. 



A succession of strata similar to those present in Iron Bidge are well 

 exposed at Cascade Falls, 5 miles east of De Pere and about 10 miles 

 south of Green Bay. The iron-ore bed at Cascade Falls furnished a 

 number of fossils characteristic of the Maquoketa shale, including frag- 

 ments which resemble parts of the rays of Stenaster sp., Eurydictya 

 montifera ? Lingula cf. cobourgensis, Strophomena ivisconsinensis, Dal- 

 manella tersa, Byssonychia intermedia, B. cf. radiata, Pterinea cf. demissa, 

 and Liospira sp. These species indicate the late Ordovician (Bichmond) 

 age of the iron formation. 



The Virgiana. zone is Avell exposed in the east quarry at Marblehead, 

 about 20 miles north of Mayville., where the following section was made : 



Section of Strata exposed in the Quarry at Mardlehead 



Mayville limestone. p eet 



6. Dolomite, yellowish gray, coarse-grained, in thick layers, containing 



numerous casts and molds of large shells of Virgiana oarrandei 

 var , 12 



5. Talus-covered interval 40 



4. Dolomite, gray, crystalline, in thick, irregular layers 21 



3. Dolomite, gray, fine-grained, in layers 4 to 5 inches thick 42 



2. Dolomite, penetrated in a drilling but not exposed 58 



Maquoketa. shale. 



1. Shale, bluish gray , 1 



XXIII — Bull. Geol. Soc. Am., Vol. 27, 1915 



