INDEX TO GEOLOGY OF SARATOGA SPRINGS AND VICINITY 1 75 



Ordovicic history, 137-38 

 Orthis salemensis, 67 

 Orthoceras arcuolineatum, 50 



hudsonicum, 50 

 Orthodesma subcarinatum, 96 

 Oxydiscns sp., yy 

 Ozarkic system, 2)2' 



Pachydictya acuta var., 47 

 Paleozoic history, 136; later, 142-43 

 Paleozoic rocks of the eastern 



trough, by R. Ruedemann, 66-99 

 Paleozoic rocks of the western 



trough, by H. P. Gushing. 30-32 

 Paleschara ulrichi, 96 

 Parastrophia hemiplicata. 96 

 Pegmatite, 18. 22-23, 25 

 Pelagiella hoyti, 42 



minutissima, 42 

 Peneplain, 8 

 Phlogopite, 20 

 Phyllodictya varia, 47 , 

 Plaesiomj's retrorsa. 96 

 Plagioclase, 18 

 Platyceras primaevum. y2 

 Plectambonites pisum. 80. 81, S2 



sericeus, 97, 98. 99 

 typus, 96 

 Plectorthis cf. whitfieldi, 96 

 Pleistocene history, 146-48 

 Polytoechia apicalis, 77 

 Pontobdellopsis. 98 



cometa. 50, 98 

 Porter Corners. 20, 44; graphite, 148 

 Potsdam sandstone. 31. 32. 34-35, 



58, 59. 60. 63, 136-37, 141, 165 

 Precambric rocks. 16-30 

 Proetus undulostriatus. 97, 98 

 Prosser, C. S.. cited, 38, 46, 54. 56. 



59 

 Protorthis minima, yy 

 Protospongia, 67 

 Pterotheca cf. canaliculata, 97 

 Ptychoparia, 3y 



matheri, 38 

 Pyrite, 20 

 Pvroxene. t8. 20, 28 



Quaker Springs, 87, 152 

 Quartz, 18, 20, 21, 23, 28 

 Quartz-feldspar, 19 

 Quartz-pyroxene, 19 

 Quartzites, 17, 19 



Rafinesquina sp., 80 

 alternata, 76, 96. 97 



Rensselaer county, table showing the 

 Lower Cambric series, 68 



Retiograptus geinitzianus, 92 



Rhinidictya mutabilis, 47 



Rock City Falls, 46, loi, 151 ; fault, 

 59-60 



Rose quartz, 23 



Rowlands Mill, 46, 151 



Ruedemann, R., Canajoharie shale. 

 48-51 ; Control of development and 

 history of Saratoga region by the 

 geology, 168-70; Paleozoic rocks 

 of the eastern trough, 66-99; 

 Relation of the Saratoga mineral 

 springs to structure of the shale 

 belt of the upper Hudson valley. 

 165-67; Structural geology of the 

 shale belt, 99-115; work on Schuy- 

 lerville quadrangle, 6; classifying 

 and mapping shales, 6; cited, 42, 

 48, 74, 81, 152, 157 



& Cushing, H. P., Historical 



geology, 135-48 



Rysedorph hill. 81 



Rysedorph Hill conglomerate, 66, 

 80-84. 93. 105. 108, 113, 142 



Sacandaga creek. 12 



St Clements. 61 



St Johnsville, 10 



Sand terraces, 14 



Sandstones. 7 



Saratoga fault. 60. 61-62 



Saratoga Graphite Co.. 149 



Saratoga lake. 15 



Saratoga quadrangle, location and 



character. 6-7; part of, mapped 



by W. J. Miller, 5 

 Saugerties. 115 

 Scapolite, 20 



