150 NEW YORK STATE MUSEUM 



Sp i rifer murchisoni and Rhipidomella muscu- 

 lo s a. In the midst of these folded sandstones, however, on the 

 east flank of the anticline, lies a darker sandstone band in which 

 the grains are notably coarse, in places actually pebbles, and here, 

 in bad preservation, occurs the typical sand fauna of the New York 

 Oriskany;. that is to say, Rensselaeria ovoides, Lep- 

 taena ventricosa, Spirifer arenosus, Lepto- 

 coelia flabellites,Hipparionyx proximus, D i a - 

 phorostoma ventricosa and a large Pterinea ; no other 

 fossils have been observed and none at all that would be regarded as 

 tying this fauna and its formation to the deeper waters or the 

 deeper water fauna. 



The Barre limestone at the eastern end of the section is known 

 to contain the trilobite Dicranurus, and this alone is evidence of its 

 very earliest Devonic age, and the horizon is thus, rightly I think, 

 construed as the base of the entire Devonic section. The contact 

 between this and the Perce limestone on this cliff section is a fault, 

 as is very clearly shown. It is probable that the Barre limestone 

 is a term lying beneath the limestones of the Pic d'Aurore fold, in 

 view of the recognizable difference in petrology and the fauna. The 

 Pic d'Aurore series is the term now used for this succession of 

 predominant sand sedimentation with intermingled limestone beds, 

 and it may be regarded as extending from the base of the Perce 

 limestone down to the contact line between the sandstones and top 

 of the Barre limestone. 



The contact of the Devonic with the earlier beds is an uncon- 

 formity at the west of this section and both Siluric and Ordovicic 

 strata are exposed at the base of the cliff near the mouth of the 

 coulee which runs down at this point from the face of the Grand 

 Coupe in Perce mountain. On the other side of this coulee the 

 cliff is composed of further development of the corrugated Siluric 

 beds above with Ordovicic beds beneath. From this point the 

 section on to Cannes-des-Roches or the northwest end of the cliff's 

 is represented as composed entirely of the green and mottled marls, 

 red sandstones and dark shales of the Bonaventure conglomerate, 

 all of which have obviously been overturned from the Table-a- 

 rolante and which form only a thin veneer overlying the seaward 

 edges of the Siluric-Ordovicic beds. 



