CONTENTS xiii 



CHAPTER IX 



THE RISE OF MOLTEN ROCK TO THE EARTH'S SURFACE ; VOLCANIC 



MOUNTAINS OF EXUDATION 



PAGE 



Prevalent misconceptions about volcanoes Early views concerning vol- 

 canic mountains The birth of volcanoes Active and extinct vol- 

 canoes 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 



The mechanics of crater explosions Grander volcanic eruptions of cinder 

 cones The eruption of Volcano in 1888 The eruption of Taal 

 volcano on January 30, 1911 The materials and the structure of cin- 

 der cones The profile lines of cinder cones The composite cone 

 The caldera of composite cones The eruption of Vesuvius in 1906 



The sequence of events within the chimney The spine of Pele* 

 The aftermath of mud flows The dissection of volcanoes The 

 formation of lava reservoirs Character profiles Reading references 116 



CHAPTER XI 

 THE ATTACK OF THE WEATHER 



The two contrasted processes of weathering The r61e of the percolating 

 water Mechanical results of decomposition: spheroidal weathering 



Exfoliation or scaling Dome structure in granite masses The 

 prying work of frost Talus Soil flow in the continued presence of 

 thaw water The splitting wedges of roots and trees The rock man- 

 tle and its shield in the mat of vegetation Reading references . . 149 



CHAPTER XII 

 THE LIFE HISTORIES OF RIVERS 



The intricate pattern of river etchings The motive power of rivers 

 Old land and new land The earlier aspects of rivers The meshes 

 of the river network The upper and lower reaches of a river con- 

 trasted The balance between degradation and aggradation The 

 accordance of tributary valleys The grading of the flood plain 



