CONTENTS. 



Vor. III. 



CHAPTER I. 



PAGE 



Connexion between the subjects treated of in the former parts of this work 

 and those to be discussed in the present volume Erroneous assumption of 

 the earlier geologists respecting the discordance of the former and actual 

 causes of change Opposite system of inquiry adopted in this work Illus- 

 trations from the history of the progress of Geology of the respective merits 

 of the two systems Habit of indulging conjectures respecting irregular and 

 extraordinary agents not yet abandoned Necessity in the present state of 

 science of prefixing to a work on Geology treatises respecting the changes 

 now in progress in the animate and inanimate world * . 1 



CHAPTER II. 



Arrangement of the materials composing the earth's crust The existing 

 continents chiefly composed of subaqueous deposits Distinction between 

 sedimentary and volcanic rocks Between primary, secondary, and tertiary 

 Origin of the primary Transition formations Difference between secondary 

 and tertiary strata Discovery of tertiary groups of successive periods 

 Paris basin London and Hampshire basins Tertiary strata of Bordeaux, 

 Piedmont, Touraine, &c. Subapennine beds English crag More recent 

 deposits of Sicily, &c. . . . . . 8 



CHAPTER III. 



Different circumstances under which the secondary and tertiary formations 

 may have originated Secondary series formed when the ocean prevailed: 

 Tertiary during the conversion of sea into land, and the growth of a continent 

 Origin of interruption in the sequence of formations The areas where new 

 deposits take place are always varying Causes which occasion this transfer- 

 ence of the places of sedimentary deposition Denudation augments the dis- 

 cordance in age of rocks in contact Unconformability of overlying forma- 

 tions In what manner the shifting of the areas of sedimentary deposition 

 may combine with the gradual extinction and introduction of species to pro- 

 duce a series of deposits having distinct mineral and organic characters 23 



c 2 



