22 CONTENTS. 



Chapter IX. — Rocks — Continued. Pa°-& 

 Sedimentary rooks — Continued. 



Nonfragmental class — Continued. 

 Oxide order — Continued. 



Silica family.- 847 



Chert _ _ 847 



Rearrangement of chert 849 



Fragmental class _ 853 



Psephite order • _ . _ 853 



Pebble, gravel, and bowlder deposits 853 



Conglomerates 855 



Schist-conglomerate and gneiss-psephite, or conglomerate-schist and 



psephite-gneiss S57 



Paammite order _ 860 



Quartz-sand family S60 



Quartz-sand rock 860 



Sandstone S64 



Quartzite 865 



Schist-quartzite or quartzite-schist 868 



Quartz-feldspar-sand family 870 



Quartz-feldspar sand 870 



Arkose 874 



Schist-arkose and gneiss-arkose, or arkose-schist and arkose-gneiss 875 



Ferromagnesian-sand family 877 



Ferromagnesian sands. 877 



Grits S79 



Gray wacke 880 



Slate-graywacke, schist-graywacke, and gneiss-graywacke; or graywacke- 



slate, graywacke-schist, and graywacke-gneiss 883 



Pelite order 886 



Mud family 886 



Shale family 892 



Slate-pelite, schist-pelite, and gneiss-pelite; or pelite-slate, pelite-schist, 



and pelite-gneiss 894 



Development of minerals of slates 898 



Development of minerals of schists and gneisses. 899 



Igneous rocks 904 



Chapter X. — The Relations op Metamorphism to Stratigraphy 907 



Introductory - - 907 



Discrimination between metamorphosed sedimentary and metamorphosed igneous rocks. 90S 



Cases of confusion 909 



Criteria for discrimination 912 



Relations of metamorphic sedimentary rocks to stratigraphy 917 



Variation in metamorphism 917 



Upon what variations are dependent 917 



Resulting variations 918 



