148 NEW YORK STATE MUSEUM 



sands are rare in the limestones, and when they do occur are quite 

 Hkely to be of smaller size. The inference from these conditions 

 has been a natural and easy one and is to this effect : that the sand 

 fauna represents the shoreward movement of the fauna of the 

 period and is composed of well-adjusted representatives and sur- 

 vivors of the deeper water. This is a conclusion which is quite 

 reasonably applicable to such conditions, for we must often interpret 

 these near-shore faunas in terms of migration from the outer sea. 



In actual succession the sand beds of the Oriskany are a later 

 term than the lime beds of Hudson, Glenerie, Highland Mills, Otis- 

 ville etc., but this fact does not affect the fauna as such ; a re- 

 adjusted element out of the more prolific deeper water reservoir. 



Turning to the expression of this Devonic episode in the north- 

 eastern Appalachians, we find a better evidence for the inferences 

 above intimated, for there it is obvious, in the first place, that there 

 is no real '' facies " relation between the sandstone fauna and its 

 environment, and it becomes perfectly clear that the sand species 

 of New York must be regarded as only happy readjustments which 

 traveled into shoal waters from the deeper biota, because this asso- 

 ciation has in full exemplification all the elements of the fauna to- 

 gether, brachiopods and gastropods with their full weight of shell, 

 in the lower or Oriskany horizon of the Grande Greve limestones. 



The Grande Greve limestones constitute a series which is faunally 

 comprehensive, for its upper beds carry clear indications of a later 

 than Oriskany fauna, while its lower beds express the Oriskany 

 element; and in its petrology it is a mass of deposits gradually in- 

 creasing in purity of lime from the bottom up, while the impurity 

 of the lower layers is not silica in the form of sand but a clay- 

 silica matrix. In the higher beds the silica becomes much more 

 obvious and often is segregated into horizontal chert masses, and 

 even where the limestone appears to be pure there is often a large 

 residuum of silica which in spots is practically composed of masses 

 of silicious sponge spicules. 



The expression of the Oriskany sedimentation episode in the 

 Grande Greve series of northeastern Gaspe is highly typical and 

 apparently perfectly normal. Here exist, for example, heavy 

 Rhynchonellas, Hipparionyx, Rhipidomella, Chonetes, Spirifer, 

 Rensselaeria and Diaphorostoma, as in the sandy Oriskany of New 

 York, with no diminution of size or weight but in a highly cal- 

 careous matrix and in association with species which farther west- 

 ward represent the earlier facies of the Oriskany in New York. 



