346 G. H. CHADWICK STRATIGRAPHY OF XEW YORK CLIXTON 



(only five feet in tlie AVallington well just soiitli) and is probabl}^ all Bear 

 Creek instead of Maplewood, or equivalent to only the upper 3 feet of 

 what has been called "Sodus'' at Rochester. It wonld be absurd to attach 

 the name Sodus permanently to this feeble unit, which is below watei- 

 level (9: 21-22) at ITalPs favorite collecting grounds around Sodus Bay, 

 where his "lower green shale*' is the middle shale, with its purple-brown 

 middle part (2 : 59, GO) and thin intercalated "pearly"^ limestones (2 : 60) 

 filled with fossils (2: 66). This shale, which constitutes the major part 

 (18 feet) of the ''upper" shale at Rochester, and which, inclusive of tlie 

 olive joortions at base and summit, reaches a maximum of 69 feet in the 

 South Granby well (nearly 55 feet at Sodus), is therefore the true Sodus 

 shale. It is perhaps the most persistent member of the group in Xew 

 York State, traceable almost to its eastern terminus. It carries : 



Lichenalia concent rica Tcntaculitcs miii at us 



Dalmanelhi clcfjantuUi var. (3 : 57) Htrcpula? sp. 



Rafincsquina corrugata Bcf/tichia lata 



Atrypa reticularis (3 : 72) Bollia lata 



Calospira nitois (Vanuxem) PJiaeops trisulcatus 



Strophosti/lus canceUatus Cahjmenclla rostrata 



Strophostt/liifi rentricosiis Calinnene vogdesi? 



The "pearly layers" consist chiefly of the shells of the ''Ort/tis nitens' 

 of Vanuxem (1842, 1:90), whose description is perfectly recognizable 

 (as first pointed out to me by Mr. Ira Edwards) and whose specimens 

 are before me — usually identified with the European Coelospira hemi- 

 spherica (Sowerby, 1839). Equally abundant in the purple shale is the 

 " Stroplieodonta' corrugata, which is i3lainly a Rafinesquina, as it has no 

 hinge denticulations. 



YEROSA IRON ORE 



This ore, typically exposed in the old workings north and west of Ve- 

 rona (9: 67, map on 66, 26, 40), is licrein identified with the highly im- 

 portant oolitic lower ore of tlie Clinton region^" and eastwarfl. A similar 

 slioreward transition is found to affect all the ores wlien traceable far 

 enough to eastward, whereas westward they grade into limestone as does 

 this ore in the Lakeport well. Its fauna is unknown, except that Van- 

 uxem found Beyricliia? lata in it near Utica (1 : 84) . Dictyoncma scalari- 

 jorme, Cyclograptus rotadentatus, and Palceodictyota cUntonensis are 

 from the shale that "directly overlies'' it (New York State Museum,- 

 Memoir 11, page 185). The writer obtained Cyclograptus from the ore 

 itself. 



^" See preceding footnote G, p. 388, which siigjiosts caution. 



