ILLUSTRATIONS XV 



Gushing : Page 



Figure 1^ — Portion of Cleveland quadrangle, showing location of 



Brooklyn channel 207 



2— Section of the Belt Line Railroad cut 207 



Branson : 



Figure 1 — Idealized section of gypsum beds 234 



" 2 — Idealized section of gypsum beds 234 



" 3 — Idealized section of gypsum beds drawn to scale 234 



" 4 — Idealized section of gypsum beds drawn to scale 234 



" 5 — Map showing hypothetical overflow basins of salt and 



gypsum deposition during Salina time 239 



Coleman : 



Figure 1 — Cross-section of the Don beds 245 



" 2 — Map showing interglacial beds in Ontario 250 



" 3 — Sections of interglacial and postglacial valleys 253 



Wright : 



Figure 1 — Obsidian containing radial spherulites and bubble cavities 266 

 " 2 — Lythophysse, with fluted tongue of obsidian projecting 



into hollow cavity, shown in center of photograph .... 266 

 " 3 — Tridymite crystals supported by needles of feldspar (?) 



in recrystallized lithophysa 267 



" 4— Radial lithophysa, in part recrystallized 268 



" 5 — Sharply fluted tongue of black obsidian glass projecting 



into lithophysal cavity 268 



" 6 — Remarkable lithophysa^ in obsidian 269 



" 7 — Lower wall of lithophysa on left side of figure G 270 



" 8 — Enlarged central part of figure 7 271 



" 9 — Diagrammatic representation of cube built up of six 



pyramids ■ 272 



" 10 — Ellipsoid-like lithophysal cavity, with central girdle of 



crystallized material 272 



" 11 — Etched surface of obsidian glass, moldavitic in character. 277 



" 12 — Etched surface of a small obsidian fragment 278 



Chadwick : 



Figure 1 — Map showing location of Canton quadrangle and belts of 



formations adjacent thereto 288 



" 2 — Folded Paleozoic rocks on Ogdensburg and Canton quad- 

 rangles 289 



" 3— Partial geologic map of Canton (quadrangle, showing re- 

 lation of Paleozoic rocks to pre-Cambrian belts 291 



" 4 — Crumpling of Beekmantown limestone in old quarry at 



Yaleville 292 



" 5 — Inverted buckle crossing Raquette River below bridge at 



Norfolk 292 



" 6 — Actual cross-section of Potsdam beds one mile northwest 



of Brick chapel, New York 293 



" 7 — Cross-section of Potsdam outlier on Harrison Creek 293 



«« 8 — Ideal cross-section of same valley before deformation 



began 293 



" 9 — Same valley after deformation ; dotted line shows present 



erosional profile. 293 



