INVESTIGATORS OF THE MEMNA 301 



characters; for though without doubt every group embraces its peculiar 

 fossils, yet in all localities these may not be so marked as to excite atten- 

 tion, and in some may possibly be absent. It thus becomes a desideratum 

 to distinguish rocks by names which cannot be traduced, and which, when 

 the attendant circumstances are fully understood, will never prove fal- 

 lacious. The basis of this nomenclature is derived from localities; and 

 the rock or group will receive its name from the place where it is best 

 developed. For example, the rock denominated in the section [of the 

 last report] calcareous shale, simply to distinguish it from the green 

 argillaceous shales below, will be called Rochester shale. In lithological 

 characters it is extremely like one far higher in the series, but the fossil 

 contents are entirely different. This contains the Asaphus caudatus, 

 Trimerus delpJiinocephalus, Platynotus Boltoni, besides species of Orthis 

 and Dellhyris, all peculiar to this rock, and the characters if studied and 

 well understood at Rochester, will guide the observer in all subsequent 

 examinations. The limestone at Lockport excavated for the passage of 

 the canal, we propose to call Lockport limestone. At this place the rock 

 possesses in an eminent degree the geodiferous character, which has hith- 

 erto given it its name; but this is quite inapplicable to the same rock 

 where seen in Wayne County'' (1839, pages 288-289). 



In the Fourth Annual Report (1840, pages 374, 453-455) we meet for 

 the first time with the term Medina in Yanuxem's report. Evidently he 

 did not intend to stand sponsor for the name, as Medina is not in his 

 geological district (Third), but is in Hall's Fourth District. Vanuxem 

 writes : "Medina sandsto7ie. Called in former reports the red sandstone 

 of Oswego. Predominant colour red, more rarely whitish and greenish. 

 This rock is confined to Oswego County, to the high grounds of Oneida 

 at Florence village, and other parts of the town of Florence, and to the 

 extreme north parts of the counties of Onondaga and Cayuga" (page 374). 



Hall in the same report writes as follows: "Medina, sandstone, red 

 marl and shale. This rock is the lowest in the 4th District, it being 

 found bordering the shore of Lake Ontario, from Niagara River to the 

 eastern limits of Wayne County." He intimates that it rests on the 

 Salmon River group, which is now known to be of Lorraine or Maysville 

 age. The fossils mentioned are the regulation Medina species. 



In the final report,^^ in 1843, Hall gives a general summary of the 

 Medina, and here he notes as synonyms all the names given above and as 

 well Niagara sandstone, but as to this latter name states nothing fur- 

 ther. He says: "At Medina, on the Oak-orchard Creek, we have the 

 best exposure of the mass which exists in the State, and hence its name. 



^ Geol. N. Y., Fourth Dlst, 1843, pp. 24, 34-57. 



