REPORT OF THE DIRECTOR I919 I23 



of pre-Utica shales in the upper Hudson and lower Mohawk valleys. 

 The result of this work was published in 1912.^° 



In this paper the entire terrane of pre-Utica age, but of Utica 

 aspect, in the lower Mohawk and upper Hudson River valley is dis- 

 tinguished as the Canajoharie shale, while the Lorraine facies, con- 

 sisting of gray shale and sandstone, is termed the Schenectady beds 

 and the similar beds of a more easterly situated basin or trough are 

 called the Snake Hill beds. All these are of Trenton age, with the 

 Schenectady beds possibly reaching also into Utica time. 



The following graptolite horizons were distinguished in the Cana- 

 joharie shale, in descending order: 



4 Zone of Climacograptus spiniferus, Diplograptus vespertinus, 

 etc. 



3 Zone of Lasiograptus eucharis, etc. 



2 Zone of Glossograptus quadrimucronatus cornutus, Corynoides 

 calicularis, etc. 



I Zone of Diplograptus amplexicaulis, Corynoides calicularis, etc. 



It is, however, obvious from sections (published op. cit., p. 15 ff.) 

 from Swartztown and Morphy creeks, that, in the shales exposed 

 about 20 miles east of the typical Canajoharie sections, a zone pre- 

 cedes which is characterized byMesograptus mohawk- 

 e n s i s . This zone, while in the Morphy creek section reaching a 

 considerable development, is in the Canajoharie section (ibid., p. 22) 

 represented only in its last stage, on top of the basal Trenton (Glens 

 Falls limestone). Since Diplograptus amplexi- 

 caulis does not appear until the upper part of the zone, the latter 

 must precede the lowest zone of the Canajoharie shale, namely, that 

 with Diplograptus amplexicaulis. We will distinguish this zone in 

 the shales of Morphy and Swartztown creek as 3one of Mesograptus 

 mohawkensis and refer the zone, although but slightly represented at 

 Canajoharie, to the Canajoharie shale. 



An outcrop of shale at the Carlsbad spring near Saratoga (see 

 Bulletin 169, p. 50) proves the presence of this zone also in the upper 

 Hudson River valley. 



The Snaike Hill beds have furnished a rich fauna of other fossils 

 than graptolites, but only meager graptolite faunules except in two 

 cases. They have in common with the Canajoharie shale (see Bul- 

 letin 162, p. 64) the occurrence of Diplograptus am- 

 plexicaulis and Corynoides calicularis, 

 but otherwise bear in both the graptolite and nongraptolite biota a 



'" R. Ruedemann, The Lower Siluric Shales of the Mohawk Valley. N. Y. 

 State Mus. Bui. 162, 1912. 



