P. E. Raymond — Fauna of the Chazy Limestone. 363 



in the fauna is seen at L'Orignal, only 16 miles from Hawkes- 

 bury. Here is found a section less than 200 feet in thickness, 

 with sandstone at the base and limestone in the upper portion. 

 The fauna changes abruptly, several species occurring there 

 which are unknown further east. The typical Chazy fossils 

 found here are : Camarotoechia plena , Paphistoma stamineum, 

 and 2lalocystites murchisoni. From this locality west to 

 Allumette Island, a distance of 115 miles, the same succession 

 of strata may be found, and about the same fauna. All 

 through the Ottawa Yalley the Chazy is represented by a 

 formation which is sandstone at the base and limestone above. 

 In its most western exposures, the limestones are absent and 

 only the sandstone remains. 



The base of the Chazy is always a sandstone, but this does 

 not carry the same fauna in all regions, nor does the zone 

 which rests upon it always have the same fauna. In the Lake 

 Champlain region, the sandstone always contains Lingula 

 lyrainerdi ; in the Ottawa Yalley, it carries a modified Gama- 

 roto2chia plena fauna. At the type sections, Lingula brainerdi 

 is at the base of the formation, while the Camarotoechia plena 

 fauna appears TOO feet above. , 



Since the fullest development of limestone deposits of this 

 age is in the region of Chazy and Valcour Island, New York, 

 that must be the locality in which the Chazy sea persisted 

 longest. From the evidence outlined above, it would seem 

 that this sea was a shallow one, invading south and west over 

 a slowly sinking land. Since the Chazy fauna is apparently 

 developed less directly from the Beekmantown of the Lake 

 Champlain area than from that of Newfoundland, and since 

 there are many European types introduced into the Chazy, it 

 seems, probable that this sea was open to the east. 



If the sea were thus invading upon the land, the sandstone 

 would represent shore conditions. This is undoubtedly the 

 case, for the sandstone in both the Champlain and Ottawa 

 valleys frequently presents evidences of shore origin in cross 

 bedding, ripple marks, and worm burrows. 



If the sea were invading south ward in the region now occu- 

 pied by the Champlain Yalley, the sandstone should be younger 

 and younger in age as it is traced from north to south. That 

 this is actually the case is shown by the faunas, for at Yalcour 

 Island all the strata of the Hebertella exfoliata division, 300 

 feet in thickness, were deposited before the Maclurites magna 

 fauna became prominent, while at Crown Point this second 

 fauna follows immediately upon the basal sandstone. 



During the greater part of Chazy time, the transgression is 

 southward, but later the shore began to move westward also. 

 The region of the Ottawa Yalley was then invaded, and the 



