The zones of fracture and flow—Experiments which illustrate the fracture and flow of solid bodies—The arches and troughs of the folded strata—The elements of folds—The shapes of rock folds—The overthrust fold—Restoration of mutilated folds—The geological map and section—Measurement of the thickness of formations—The detection of plunging folds—The meaning of an unconformity—Reading references 40 CHAPTER VI THE ARCHITECTURE OF THE FRACTURED SUPERSTRUCTURE The system of the fractures—The space intervals of joints—The displacements upon joints: faults—Methods of detecting faults—The base of the geological map—The field map and the areal geological map—Laboratory models for study of geological maps—The method of preparing the map—Fold _vs._ fault topography—Reading references 55 CHAPTER VII THE INTERRUPTED CHARACTER OF EARTH MOVEMENTS: EARTHQUAKES AND SEAQUAKES Nature of earthquake shocks—Seaquakes and seismic sea waves—The grander and the lesser earth movements—Changes in the earth’s surface during earthquakes: faults and fissures—The measure of displacement—Contraction of the earth’s surface during earthquakes—The plan of an earthquake fault—The block movements of the disturbed district—The earth blocks adjusted during the Alaskan earthquake of 1899 67 CHAPTER VIII THE INTERRUPTED CHARACTER OF EARTH MOVEMENTS: EARTHQUAKES AND SEAQUAKES (_concluded_) Experimental demonstration of earth movements—Derangement of water flow by earth movement—Sand or mud cones and craterlets—The earth’s zones of heavy earthquake—The special lines of heavy shock—Seismotectonic lines—The heavy shocks above loose foundations—Construction in earthquake regions—Reading references 81 CHAPTER IX THE RISE OF MOLTEN ROCK TO THE EARTH’S SURFACE; VOLCANIC MOUNTAINS OF EXUDATION Prevalent misconceptions about volcanoes—Early views concerning volcanic mountains—The birth of volcanoes—Active and extinct volcanoes—The earth’s volcano belts—Arrangement of volcanic vents along fissures, and especially at their intersections—The so-called fissure eruptions—The composition and the properties of lava—The three main types of volcanic mountain—The lava dome—The basaltic lava domes of Hawaii—Lava movements within the caldron of Kilauea—The draining of the lava caldrons—The outflow of the lava floods 94 CHAPTER X THE RISE OF MOLTEN ROCK TO THE EARTH’S SURFACE; VOLCANIC MOUNTAINS OF EJECTED MATERIALS