330 G. H. CHADWICK STRATIGRAPHY OF XE^V YORK CLI>'TON 



the early New York survey from the localities descri1>ed in their reports 

 (1, 2) has been of much assistance. 



The cooperation of one of our students. Miss Flora Crombie, and aid 

 received from Mr. Ira Edwards, now of the Milwaukee Museum, arid 

 from Prof. W. J. 3Iiller are gratefully acknowledged. Since the prepa- 

 ration of the manuscript very kind criticism and suggestions have been 

 received from Doctors 31. Y. Williams, E. M. Kindle, and C. K. Swartz, 

 and especially from the c-ensor of the paper. Professor Schuchert. 



C0MPARIS02f OF WESTERN SeCTIOXS 



The sections will be considered in order from west to east, beginning 

 at Kochester. The horizontal datum line in the charts is the base of the 

 Eochester shale. The Eochester section of the "Clinton" has just been 

 summarized and will be found drawn to scale at the left end of figure 1. 

 It consists, in the old interpretation, of two limestones and two shales, 

 with an iron-ore bed. The next continuous section is that of the test hole 

 at Wallington, near Sodus. In this there are, however, th ree limestones 

 and three shales, with the same bed of iron ore. The new limestone 

 member is found to come in between the dark graptolitic portion of the 

 upper shale at Eochester and the purpUsh shale portion with its ^'pearly 

 layers."' Both of these two upper shale members have gained considerably 

 in thickness, whereas the bottom shale and also the upper limestone have 

 apparently diminished. It is evident on closer consideration, however, 

 that it is the lower shaly portion of the upper Hmestone at Eochester 

 which in this well has become the topmost 20 feet of shale — a shale said 

 to be similar to the Eochester shale and highly fossiliferous. But the 

 graptolite shale itself has also expanded to 15 feet. At the base of the 

 section the Thorold sandstone appears to be missing, so that the attenu- 

 ated basal "Clinton" shale rests directly on the variegated Medina shale. 



With but minor variations, the relations shown in the Wallington well 

 continue eastward to the Oswego Eiver. All the Lbnestone members, it 

 should be observed, become increasingly shaly, while the shale members 

 (except the basal shale) continue to thicken and several new ore seams 

 make their appearance. 



Two of these new ore horizons CKicur first in the section next east of 

 Wallington^ that of the test hole at Wolcott. Here an important ore 

 comes ia just above the middle limestone.. This ore outcrops at the old 

 furnace north of Wolcott and at a few other points to the west. Another 

 new but thin ore bed appears at the top of the lower limestone (here 

 mostly shale) and is exposed in the diggings at Sterling Station, a few 



