13 



CONTENTS 



CHAPTER X 

 METAMORPHISM 



PAGE 



Kinds of Metamorphism „ 34I 



Contact Metamorphism. Regional Metamorphism. 

 Classification of Metamorphic Rocks , 344 



Quartzite. Marble. Slate. Schist. Gneiss. 

 Summary of Causes of Metamorphism . . 347 



Heat. Moisture. Pressure. 

 Arrangement of Minerals 348 



Crystallization. Granulation. Relation of Cleavage to Pressure. From 

 Igneous, through Sedimentary, to Metamorphic Rocks. Weathering of 

 Metamorphic Rocks. Economic Importance. 



CHAPTER XI 



MOUNTAINS AND PLATEAUS 



Classification of Mountains 352 



Mountains of Accumulation. Residual Mountains. Fault or Block Moun- 

 tains. Laccolith Mountains. Domed Mountains. Complexly Folded 

 Mountains. 



Origin and Development of Folded Mountains 358 



Geosynclines. Lateral Pressure. Experiments in Mountain Building. 

 Rate of Folding. To What the Topographic^Features of Folded Moun- 

 tains are Due. Cycle of Erosion of Mountains. 



Theories of Mountain Building 364 



Cause of Lateral Pressure. The Elevation of Plateaus and Mountains. 

 The Theory of Isostasy. The Distribution of Mountains. Perma- 

 nence of Continents and Ocean Basins. Age of Mountains. 



CHAPTER XH 



ORE DEPOSITS 



Characteristics of Deposits 370 



Ores in Ready-made Cavities. Fissure Deposits. Form and Extent of 

 Veins. Source of Vein Material. Cause of Precipitation. Replace- 

 ment Deposits. Weathering and Concentration of Ores. Magmatic 

 Segregation. Placer Gold Deposits. Sedimentary Iron Deposits. 



PART II. HISTORICAL GEOLOGY 



CHAPTER XIII 

 HISTORICAL GEOLOGY 



Fossils 377 



The Original Substance may be Preserved. Replacement. Casts and 

 Molds. Footprints, Trails, etc. Entombment of Plants and Animals. 

 Imperfection of the Record. 



