CONTENTS. XV 



CHAPTER IX. 



THE MOVEMENTS AND DEFORMATIONS OF THE EARTH'S BODY 



(DIASTROPHISM). 



PAGE 



Minute and Rapid Movements 526 



Earthquakes 527 



Points of origin, foci, 527. The amplitude of the vibra- 

 tions, 529. Destructive effects, 530. Direction of throw, 

 531. Rate of propagation, 532. Sequences of vibrations, 

 533. Gaseous emanations, 533. Distribution of earth- 

 quakes, 533. 



The Geologic Effects of Earthquakes 534 



Fracturing of rock, 534. Changes of surface, 534. Effects 

 on drainage, 535. Effects on standing water, 535. Changes 

 of level, 536. 



Slow Massive Movements 537 



Present movements, 538. Fundamental conceptions, 539. 



Nearly Constant Small Movements 540 



Reciprocal features, 541. 



The Great Periodic Movements 542 



Mountain-forming movements, 542. Distribution of 

 folded ranges, 543. Plateau-forming movements, 543. Con- 

 tinent-forming movements, 544. Relations of these move- 

 ments in time, 545. Relations of vertical to horizontal 

 movements, 545. The squeezed segments, 546. The de- 

 pressed or master segments, 546. The differential extent of 

 crustal movements, 548. 



The Causes of Movement 551 



General Considerations 551 



1. The centripetal agencies 552 



Gravity, 552. Molecular and sub-molecular attrac- 

 tions, 554. Cohesion and crystallization, 554. Diffu- 

 sion, 555. Chemical combination, 556. Sub-atomic 

 forces 556. 



2. The resisting agencies 557 



Heat, 557. All resistance perhaps due to motion, 558. 



Alternative Views of Original Heat Distribution 559 



Thermal distribution on the convection hypothesis, 559. 

 Level of no stress, 561. Thermal distribution on the hypoth- 

 esis of central solidification , 562. Thermal distribution under 

 ihe accretion hypothesis, 564. 



