CHAPTER IX.

THE MOVEMENTS AND DEFORMATIONS OF THE EARTH’S BODY

(DIASTROPHISM).

+Minute and Rapid Movements+ 526

_Earthquakes_ 527

Points of origin, foci, 527. The amplitude of the vibrations,

529. Destructive effects, 530. Direction of throw, 531. Rate

of propagation, 532. Sequences of vibrations, 533. Gaseous

emanations, 533. Distribution of earthquakes, 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.

Continent-forming movements, 544. Relations of these

movements in time, 545. Relations of vertical to horizontal

movements, 545. The squeezed segments, 546. The depressed

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 attractions, 554.

Cohesion and crystallization, 554. Diffusion, 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 hypothesis of

central solidification, 562. Thermal distribution under the

accretion hypothesis, 564. _Computed Pressures, Densities,

and Temperatures within the Earth Based on Laplace’s Law_ 564

Recombination of material, 568. Comparison of the hypotheses,

568.

+Observed Temperatures in Excavations+ 569

Explanations of varying increment, 570. The permeation and

circulation of water, 570. Chemical action, 570. Differences

in the conductivity of rock, 571. Compression, 571. Gradients

projected, 571. The amount of loss of heat, 572. The amount

of shrinkage from loss of heat, 572.

+Other Sources of Deformation+ 574

Transfer of internal heat, 574. Denser aggregation of

matter, 574. Extravasation of lavas, 574. Change in the

rate of rotation, 575. Distribution of rigidity, 578.

_Sphericity as a Factor in Deformation_ 580

The influence of the domed form of the surface, 581.

Theoretical strength of domes of earth-dimensions, 581.

Stress-accumulation independent of sphericity, 583. The

actual configuration of the surface, 584. Concave tracts,

584. General conclusion, 588.

Geology, Vol. 1 [of 3] · 第 9 / 22 章