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.