INTRODUCTION 177 



to the land and its dwellers. Only 32% pages out of 300, up to the be- 

 ginning of the Quaternary, have to do with terrestrial things, even the 

 dinosaurs almost escaping notice. The dry land was evidently of small 

 importance. 



It is not unnatural that in the beginning geology should devote itself 

 mainly to things marine, for the favored haunts of men are almost all 

 founded on stratified rocks. Werner's idea of a world deposited layer by 

 layer from a primeval sea seemed reasonable when he lectured in Frei- 

 berg, though the Bergakademie stands on eruptive gneiss; and when 

 William Smith began stratigraphic geology, on an island where one can 

 never get many miles from the sound of the surf, he had to collect sea- 

 shells from the rocks as coins with Avhich to date the formations. 



The regular succession of marine faunas in the stratified rocks laid the 

 foundation for our chronology, showed the orderly development of living 

 beings, and made possible the correlation of the rocks of different coun- 

 tries. The study of marine fossils was necessary to the building up of 

 historical geology on a sound basis, therefore, so that the almost exclusive 

 attention given to the seas and their life was not unjustified. In those 

 earlier clays continents had a place in geology mainly as limiting the 

 migrations of marine faunas or as providing sediments for the shallow 

 seas. In other respects they were largely negative things, vacuums where 

 nothing took place, since they provided no fossil-bearing beds, while the 

 waters around them were swarming with life and activity. ■ 



It seemed quite the correct thing thirty-five years ago, when the older 

 men among us were students, to spend most of our time bending over 

 rows of brachiopods in museum cases and memorizing lists of type fossils, 

 so as to fix the age of rocks we might encounter in our field work. In 

 those days the wash of the waves and the smell of the seashore seemed to 

 permeate geology, and dry land was seldom mentioned or thought of by 

 professors or students. Most of geology consisted of stratigraphy and 

 invertebrate paleontology. Bluff old Credner had some justification for 

 devoting nine-tenths of his historical geology to a consideration of the 

 doings of the sea and its inhabitants. The land had scarcely been discov- 

 ered. Even the "Age of Mammals" was named and subdivided in ac- 

 cordance with the proportions of extinct to living shell-fish and not from 

 the rapid evolution of the mammals and their differentiation into the 

 highest forms of animals the world has known. 



DlSCOVEEY OF THE LAND 



It can not be said that the early geologists entirely ignored the land. 

 An unmistakable land surface, like the "dirt bed" of the English Pur- 



