xiv CONTENTS. 



PAGE! 



pressure, 448. Deep-seated metamorphism, 449. Comple- 

 tion of the rock cycle, 449. 



Various Classifications and Nomenclatures 449 



New System of Classification and Nomenclature 451 



The Proposed Field System 451 



The phanerites, 451. The aphanites, 452. 



The Proposed Quantitative System 454 



Reference List of the More Common Minerals 460 



Reference List of the More Common Rocks 467 



Ore Deposits 474 



Concentration, 474. Exceptional and doubtful cases, 474. 

 Original distribution, 475. Magmatic segregation, 475. Ma- 

 rine segregation and dispersion, 476. Origin of ore regions, 

 477. Surface residual concentration, 478. Purification and 

 concentration, 478. Concentration by solution and repre- 

 cipitation, 479. Location of greatest solvent action, 480. 

 Short-course action, 481. Long-course action, 481. Sum- 

 mary, 483. The influence of contacts, 484. The effect of 

 igneous intrusions, 484. The influence of rock walls, 484. 



CHAPTER VIII. 

 STRUCTURAL (GEOTECTONIC) GEOLOGY. 



The structural phases which rocks assume, 486. 



Structural Features of Sedimentary Rocks 486 



Stratification, 486. Lateral graduation, 488. Special 

 markings, 489. Concretionary structure, 490. Secretions, 

 497. 



Structural Features of Igneous Rocks 498 



Structural Features Arising from Disturbance 500 



Inclination and folding of strata, 500. Joints, 510. 

 Sandstone dikes, 514. Faults, 514. The significance of 

 faults, 521. Effect of faulting on outcrops, 522. 



