2 9 



recognizable as far west as Minnesota. The fossils char- 

 acteristic of the upper zone are Prasopora simulatrix and 

 Dinorthis meedsi. The principal fossils of the next 

 lower zone are, Cryptolithus tessellatus and Triplecia nuclea, 

 while in the zone below is the nautiloid, Trocholites canaden- 

 sis. Finally, at the base, are a few feet of strata with 

 Parastrophia hemiplicata. The first fauna occupies the 

 upper four-fifths of the formation, and the last three the 

 lower fifth. The total thickness is about 500 feet (150 m.). 



QUEBEC CITY FORMATION. 



The Quebec City formation consists of hard, fine-grained 

 limestone, very dark shale, and thick and thin beds of 

 limestone conglomerate. The shales are frequently more 

 or less altered and show secondary cleavage, but sometimes 

 contain rather well preserved graptolites, among them such 

 forms as Corynoides calycularis, Climacograptus bicornis, 

 and Cryptograptus tricornis, fossils which are indicative 

 of a mid-Trenton age. A few fossils other than graptolites 

 have been found, but they are small shells, of no value in 

 correlation. 



The pebbles in the conglomerate are quite fossiliferous 

 and contain such fossils as Plectambonites pisum, Tretaspis 

 diademata, Lonchodomas hastatus, and Nidulites, all un- 

 known in the typical Trenton. Strata containing these 

 fossils are now known to occur in eastern Pennsylvania 

 and Virginia, where they are found in that part of the 

 Ordovician section which elsewhere is usually occupied 

 by the Black River and Lower Trenton. The thickness 

 of the Quebec City formation is unknown. 



LEVIS FORMATION. 



The Levis formation consists mostly of hard, grey, green, 

 and red shale, thin-bedded hard, blue and light grey lime- 

 stone, and thick and thin beds of limestone conglom- 

 erate. Neither the top nor bottom of the formation 

 is known. About 1,000 feet (300 m.) of strata are 

 exposed in the vicinity of Levis. The shales contain a 

 graptolite fauna, the more prominent species being Phyllo- 

 graptus typus and Tetragraptus quadribranchiatus . The 

 limestones contain Shumardia granulosa, Phyllograptus, 



