COIN^TEN^TB. 



CHAPTER I. 



Page. 

 Gekekal considerations relating to the topography and geological history of the 

 High Plateaus and their relations to the Plateau Province of wiuch tuey form 



A I ART 



Situation of the High Plateaus.— The several ranges and intervening valleys.— Relations of High 

 Plateaus to the Plateau Province at large.-Geological history of the province.-Its lacustrine 

 strata.- Its emergence and desiccation.-Its erosion.-Its drainage system.— Origin of its 

 peculiar features. 1-24. 



CHAPTER II. 



Classification of the volcanic rocks 



A discussion of principles of classification and the objects to he g;-''^--Cl"««'«'=='^3.y™;^ 

 in accordant ^vith chemical constitution.-Correlations bet^veen chcmKal «"" f;^;'*'"" "" 

 the one hand and mineral and physical constitution on the f ''^--^f ''l^'^'^' f*" "7 

 Correlation between texture and geological age.-Von Cotta's view adopted.-The porphy- 

 ritic texture.-Acid and basic rocks.-Sabdivision^rhyolite, trachyte, andesite, basalt. 



25 



Structural geology of the High Plateaus 



Faults and monoclinal flexures.-The principal faults descrlbed.-A discussion of their age.- 

 Ancient displacements.-Parallelism of faults to the ancient shore line.-A compaiison of 

 the structural forms prevailing in the Park, Plateau, and Basin Provinces. 25-54. 



CHAPTER III. 



Volcanic phenomena presented in the district and a general discussion of them.. .. 55 



Initial epochs of emption.-Order of succession of eruptions.-Richthofen's law of succession.- 

 Fragmental volcanic rocks.-Tufa8.-Volcanic conglomerates.-Ongm of the clastic beds.- 

 Metamorphism of tufas. 55-81. 



CHAPTER IV. 



82 



8^112. 



