horizons and fossils 341 



Horizons and Fossils 



general observations 



The subdivisioiial names used in this paper will now be defined and 

 their best known fossils listed, beginning with the basal shales. The 

 Thorold and Oneida need no redescription. The lists of fossils are pre- 

 liminary, compiled chiefly from Hall (3) and admittedly incomplete, but 

 they may be useful. In some instances the fossils liave'furnished gratify- 

 ing confirmation of the correlation based on the stratigraphy, and in no 

 case have they conflicted with it. But the stratigraphy has always been 

 the main guide. 



MAPLEWOOD SHALE 



The maximum exposure is in the Genesee gorge at Maplewood Park, 

 Rochester, where 21 feet of fine-grained, unctuous, bright-green, non-fos- 

 siliferous shale of imiform texture rest on the Thorold sandstone. This 

 is HalPs "lower green shale" and HartnageFs "Sodus" (8: 13), exclusive 

 of the uppermost three feet. This shale probably terminates eastward 

 without reaching Sodus, the true Sodus shale being a higher member. 

 The stratigraphic relations of the Maplewood are with the beds below 

 rather than above it. So far as now known to the writer, its only fossil 

 is the Arthropliycus alleghaniense, reported by Schuchert (following 

 Logan, Geology of Canada, page 313) at Thorold (12:310) in a green 

 shale of similar position.^ The fossils sometimes quoted from this horizon 

 appear all to come from the Bear Creek or other higher division. 



SAU QUOIT BEDS 



This name is temporarily extended over all the shale and sandstone 

 beds between the Oneida conglomerate and the oolitic ore bed in the Oris- 

 kany and Sauquoit valleys, about 100 feet thick, with the type section on 

 SAvift Creek, north of Sauquoit village (1:84) and in its vicinity. It 

 may be desirable later to restrict the term to some definite unit within 

 this series, in which are probably present Sodus, Martvillc, and perhaps 

 Maplewood and other horizons. The fossils are : 



At'istophycusf of. hetcrophyllum Jliisopliycus suhaugalatum 



B uthotrephis gracilis Rusophycus p udicum ( Mloha 1:83) 



Buthotrcphif! (/racilis iittennrdia Asterophycus? palmatwm (3 :20, PI. fJ) 



Chondrites framosus (3:21) Blastophyciisf impudicum (3:20) 



Palwophycus sp,? (3 :22, PI. 8, f. :V) Arthraria diccphala, nam. nov. 



Rusophycus clavatum Dactylophycus? sp. (3 : PL 8, f.5) 



8 See preceding footnote 3, p. .'i:U. 



XXVI— Bull. Geol. Soc. Am., Vol. 20, 1017 



