208 INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



The lithologic and faunal similarities of this terrane to- those of Dease River, in 

 latitude 60° north, and of the Alaska Range indicates the persistence of like 

 geographic conditions along the trend of the Cordillera in middle and late Ordovician 

 time. Ulrich says : 



The graptolite faunas in the. Cordilleran basins west of the Rockies from Nevada to Alaska 

 seem to belong to nearly the same horizon. Its age appears to be intermediate between the 

 Levis-Tetragraptus zone and the Normans Kill of the Atlantic side. 



M 19-20. GASPE PENINSULA. 



Along the south shore of the St. Lawrence, according to Logan, ^*^^ are black 

 shales and gray calcareous sandstones of middle and possibly later Ordovician age. 

 They have been described by Dawson ^®'' as the Marsouin River formation, and the 

 horizon of the graptolitic fauna which they contain is discussed by Lap worth, ^^^ 

 who states, under the heading " Griffin Point or Marsouin River zone:" 



The most characteristic forms from the zone are — 



Didymograptus Sagittarius (Hall non Hisinger). 

 Coenograptus gracilis Hall. 

 Dicellograptus sextans Hall. 

 Lasiograptus mucronatus Hall. 

 Climacograptus antiquus Lapworth. 

 Diplograptus whitfieldi Hall. 



So far as known, these. are peculiar to this zone, and the presence of a single one of these 

 species is sufficient to settle the age of the rock in Great Britain, and in all likelihood in America. 

 With these peculiar forms, however, are associated others which have a much longer vertical 

 range and unite this zone to the one which follows it in order of time. These species of long 

 range are — 



Dicranograptus ramosus Hall. 

 Glossograptus ciliatus EmmoBs. 

 Diplograptus putillus Hall. 

 Climacograptus scharenbergi Lap worth. 



They all pass up into the British zone next above the Ccenograptus zone, together with 

 the following species, which range up tlirough at least three complete zones: 



Diplograptus foliaceus Murchison. 

 Climacograptus bicornis Hall. 



This special Marsouin zone, now under consideration, has long been recognized by geologists 

 upon the continent of America. Its fossils were described many years ago by Prof. J. Hall, in 

 his "Paleontology of New York," from the dark shales of Normans Kjill, near Albany, in the 

 vaUey of the Hudson River. Hall also referred to the detection of the Normans Kill fossils 

 on Marsouin River by Sir WUliam Logan and the Canadian Survey; but the discovery of the 

 existence of rocks containing the Normans KiU fossils as far down as Griffin Cove and between 

 the Marsouin and Quebec, as demonstrated by the present collection, is wholly due to those 

 officers of the Geological Survey of Canada who have studied the district since the retirement 

 of Sir W. Logan. There can be no question of the general identity of this Griffin Cove rock 

 and the Marsouin Coenograptus zone with that of the Normans KOI of the Hudson River vaUey. 



Lapwprth further divides the fauna, which he calls the Trentonian, Marsouin 

 River, or Normans Kill fauna, into two subfaunas, namely : 



Subfauna A, the Coenograptus zone of Griffin Cove and the Marsouin River, answering to 

 the Middle Llandeilo beds of Great Britain to the Glenkiln beds of Scotland, etc. 



Subfauna B, the Cove Fields and Orleans subfauna, apparently destitute of Caeriograptus 

 gracilis and answering to the highest Llandeilo or Lowest Caradoc beds of England. 



