848 G. PI. CHADWICK STRATIGRAPHY OF NEW YORK CLINTON 



shales far down in the Clinton^ like the recent discovery of the "Clinton" 

 (Brassfield) Diciifonema pertenue in the Eochester shale at Rochester, 

 proves only that these species have a less restricted vertical range than is 

 commonly assigned to the graptolites. 



WOLCOTT FURNACE IROX ORE 



This is another unsatisfactory name, with all else preoccnpied, unless 

 we use some other hinomial, such as "Shaker settlement"' or "Second 

 Creek,"' from the other, rather dubious, occurrence near Alton. The bed 

 crops out at the old AVolcott furnace on AYolcott Creek, a mile north of 

 Wolcott village, but is of limited extent even in the wells. It appears to 

 carry the two bryozoans of the limestone below, and perhaps also Spirifer 

 rarliaius (3:CC)) and Halysites (3:44). 



^yILLIAM80N SHALE 



Ilartnagel, 190* (8 : 15-16), restricted. Hartnagel does not specify his 

 type locality, but as he was following Hall he doubtless had in mind 

 Hall's only mention of "Williamson (2 : G6), which reads: "In the eastern 

 part of AVilliamson, a little north of the Kidge road, the green shale with 

 graptolites occurs, and a short distance to the north of this the Pen- 

 tamerus limestone." This may mean the outcrops on Mink Creek at the 

 cusp of the "ridge" (Iroquois beach) between Williamson and East AYil- 

 liamson villages. In any case the mention of the graptolites (compare 

 2 : 75, where the species are described) fixes the horizon, while it is evi- 

 dent from the chart that the limestone a "short distance" north must be 

 the true Wolcott rather than the Reynales. Since the so-called William- 

 son or upper shale at Eochester includes both the graptolite shale and 

 (in the absence of the Wolcott limestone) the Sodus purple shale beneath, 

 we must either restrict the name to the graptolitic beds as here done or 

 else, if the usage at Eochester be insisted on, abandon it altogether. The 

 Williamson as restricted by Hall's locality reaches the extreme of 105 feet 

 in thickness in the Lakeport well as against its five feet at Eochester and 

 possible failure at Clinton. These rapid changes in bulk indicate some 

 minor diastrophic movements just 2^rior to its deposition, as is brought 

 out by text-figure 3. Its fossils are : 



Monograptus clintoncnsis Chonctes cornntus 



Retiolites venosus Spirifer radiatus 



Semicoscinium tenuiceps ( ?) Camarotoeckia emacerata 



fPaloeoglossa perovata fAirypa reticularis 



Pholidops squamiformis Leptodesma rhomhoidea 



PlectamVomtes elegantulus(2 :73 ) Modiolopsis suhalata 



