APPENDIX 3 



CONTACT LINES OF UPPER SILURIC FORMATIONS ON 

 THE BROCKPORT AND MEDINA QUADRANGLES 



TRAVERSES BY J. M. CLARKE, R. RUEDEMANN AND D. D. LUTHER, 1901 



Brockport quadrangle. Clinton beds. At Adams Basin on the 

 Niagara Fails road the Clinton limestones are exposed at one 

 or two points along the banks of Salmon creek. Not far back 

 from the railroad culvert crossing this creek was formerly a 

 small quarry in the cherty thin limestone slabs of the upper 

 Clinton (station 18; 520 ± feet A. T.). 



Station 15. In the bottom of Salmon creek at crossing of 

 first east and west road south of Adams Basin, thin relatively 

 pure Clinton limestones with Hyattella congesta 

 (elevation 525 feet A. T.). 



Still farther up stream and along the east branch about i 

 mile are more silicious Clinton flags lying close to the top of the 

 series. 



Rochester shale. Station 17 ; 20 rods beyond this point on the 

 same stream is an outcrop of Rochester shale with Spirifer 

 radiatus, Dalmanites limulurus, etc. This is 

 the base of the Rochester shale and its elevation is 570 feet 

 A. T. The change from the Clinton to the Niagara shale is not 

 marked by topographic features and there appears to be no sur- 

 face evidence of the passage of the one formation into the other. 

 South of Spencerport the contact line crosses the creek running 

 through that village at just about or near Ogden Center, and 

 follows approximately the 600 foot contour line. To the west 

 the topography indicates no abrupt or noteworthy change in 

 the position of this line but outcrops are of very rare occurrence. 

 In the traverse from Adams Basin southward no other outcrops 

 of the Niagara shale were observed. 



Lockport dolomites. Station 14. Elevation 625 feet A. T. 

 This is a spot on the farm of E. Arnold, township of Ogden 

 just east of the highway leading due south from Adams Basin 

 where a thin, quite pure somewhat crinoidal dolomite has been 

 taken out in small quantity for local construction purposes. 



