58 





Orthoclase, 219, 229 



-s. Kskcrs). 20 1 

 Ollrelitr. 231 



Outcrops of rock, 102, 108 

 tracing of, 97, 100 



>n of, to dip, 109, 1 17 

 relation of. to Mr :k> . 111. 112 

 Outliers produced by thrust-planes, 



'43 



Overlap, 118 

 Oxides, anhydrous, most frequent, 



228 

 hydrous, most frequent, 229 



Paper ruled in squares for field 



use, 28 



iv.it -mosses, 196 

 Pegmatite, 187 



.Is, use of, in field-geology, 29 



^tent types, 86 

 Petrifaction, 78 



;raphy, nature of, 54 

 Phillips, J. A., cited, 193 

 Photography in geological field- 

 work, 28 

 Pitchstone, 63 

 Plagioclase felspars, 229 

 Plants, indications of climate 



afforded by fossil, 82 

 Plication of strata, 145, 149, 151, 



184 



Plutonic rocks, 159 

 Polarised light, use of, in geology, 



249 



Porphyritic texture, 62 

 Powell, Major J. W., 49, 51 



ire, effects of, upon rocks, 



152. 185. 186, 187 

 Psilomelane, 229 

 Pulverisation, examination of rocks 



by, 236, 246 

 Pyrite, 228, 243 

 Pyroclastic rocks, 158 



Quartz, 192, 219, 228 



in weathered crusts of rocks, 57 

 Quartz porphyry, a compound 

 rock, 62 



Rabbit, assists geological In 

 gallon. 96 



fossil, 84 



Raised-beach, 87, 199 

 Red. as a colour of rocks, 70 



us texture, 63 

 Reversed bedding, 136, 137 

 Rhyolite, 63 

 Kipplc-mark, 83, 84 



rraces, 199 



Rocks, study of, 15, 16 

 determination of, 53 



:.on of, 54 

 fresh fracture and weathered 



surface of, 56 

 apparent structure and i 



of. 59 



crystalline, 60 

 amorphously aggregat- 

 simple and compound, 61 



istose, 63 

 compact, 63 

 glassy and resinous, 63 

 horny, 63 

 fine-grained, 64 

 Fragnu-ntal (Clastic), 64 

 hardness and streak of, 67 

 colour of, 68 

 feel of, 73 

 behaviour of, in mass, 73 



ing influence of, on forms of 

 mountains. 72, 74, 75 



. ing fossil iferous character of, 



79 



weathering of, 56, 81, 95 



boundary-lines of, 94 



dip, strike, and outcrop of, 102 



overlap of, 118 



unconformability of, 120 



dislocation of, 127 



curvature of, 145 



plication of, 151 



cleavage of, 152 



Igneous, 156 

 Rocks, Schistose, 176 

 Rock-salt, 61, 219, 228 

 Kock-slicing apparatus, 32, 237 

 Rock-terraces, or SeUr, 199, 200 



