x CONTENTS 



SECULAR MOVEMENTS 351 



Minor movements, 354. The great periodic movements, 354. 

 Mountain-folding, 354. Plateau-forming movements, 355. 

 Continent-forming movements, 356. Extent of the movements, 

 358. Causes of movements, 360. Original distribution of heat, 

 361. 



CHAPTER X 



VULCANISM 



INTRUSIONS 367 



EXTRUSIONS 369 



Fissure eruptions, 370. Volcanoes, 371. Distribution of vol- 

 canoes, 372. Relations of volcanoes, 376. Products of 

 volcanoes, 377. Formation of cones, 379. Lavas, 383. Vol- 

 canic gases, 385. The causes of vulcanism, 388. Modes of 

 reaching the surface, 391. 



CHAPTER XI 



STRUCTURAL (GEOTECTONIC) GEOLOGY 



ORIGINAL 394 



Of sedimentary rocks, 394. Of igneous rocks, 399. Of metamor- 

 phic rocks, 400. Features arising from disturbance, 400. 



PART II. HISTORICAL GEOLOGY 



CHAPTER XII 

 THE ORIGIN OF THE EARTH 



HYPOTHESES OF '. 415 



The Laplacian or "Nebular" Hypothesis, 416. The Meteoritic 

 Hypotheses, 419. The Planetesimal Hypothesis, 420. 



CHAPTER XIII 



STAGES OF THE EARTH'S HISTORY LEADING TO THE 

 KNOWN ERAS 



UNDER THE LAPLACIAN HYPOTHESIS l-'> 



UNDER MODIFICATION OF THE LAPLACI \\ II YH>THKSIS !.".<> 



THE PLAN! IIM \L HYPOTHESIS I--' 



