422 A. W. GRABAU PALEOZOIC DELTA DEPOSITS OF NORTH AMERICA 



now called the Canajoharie shale, the stratigraphic equivalent of the 

 Trenton limestone of the type section. That this shale contains some 

 graptolites not found in the higher horizons is to be expected. The fol- 

 lowing species seem to characterize these lower beds, according to Ruede- 

 mann : 31 



1. Corynoides curtus Dapworth 



2. Glossograptus quadrimucronatus (Hall) 



3. G. feucharis (Hall) 



4. Lasiograptus bimucronatus nmt. timidus Ruecleruann 



5. Climacograptus putillus (Hall) 



6. Climacograptus typicalis Hall 



The last of these seems to come in somewhat later than the others 

 (Euedemann). 32 The species listed under numbers 2, 3, and 6, Doctor 

 Ruedemann says (loc. cit., page 34), "the collector meets in almost every 

 outcrop of the typical Utica shale in both Canada and New York." 

 Corynoides curtus seems to be one of the graptolites restricted to the 

 lower mud beds which are found only in the eastern area and are repre- 

 sented by limestones westward. That the Upper Utica shale as exposed, 

 in the type section and northward is the equivalent of the Upper Trenton 

 limestone westward I have no doubt. Westward the Trenton limestone 

 thickens to 650 feet or more in Oswego County and northward, while the 

 Utica thins to 150 feet at Central Square and 113 feet at Stillwater. At 

 Pulaski the Utica comprises from 100 to 250 feet and at Sandy Creek, 

 Oswego County, from 250 to 300 feet. 33 In western New York the Tren- 

 ton limestone is, unfortunately, not open to observation, but from its in- 

 creased thickness and the total diminution of the shale between it and 

 the Oswego sandstone there is every reason for believing that a westward 

 replacement of the shale by limestone takes place, and that the black 

 muds succeeding the limestone in western New York are the Lorraine 

 shales, which here have a Utica facies, expressive of the westward migra- 

 tion of the zones of deposition, with the shoaling or emergence eastward. 

 As further confirmation of the soundness of the correlation of the Utica 

 shale of the Appalachian trough (including the eastern Mohawk region) 

 with the limestones forming on the margin of the Canadian shield, we 

 have the occurrence of the characteristic Utica graptolite Climacograptus 

 typicalis in the Middle Galena (Fusispira and Nematopora beds) at 

 Mantorville and Weisbachs Dam near Spring Yalley, Minnesota. 34 The 



31 Graptolites of New Vork. part ii, p. 37. 



32 See also N. Y. State Museum Bull. 42, p. 510 ff. 



33 N. Y. State Museum Bull. 30, pp. 456, 440. 442. 437. 



34 Winchell and Schuchert : Paleontology of Minnessota, p. 82. 



