138 HISTORY OF GEOLOGY AND PALAEONTOLOGY. 



changes of the earth, on the relations of fossils to the present 

 creation, and on the whole sequence of life in the course of 

 geological epochs. 



The Discourse begins with a demonstration that the surface 

 of the earth has been devastated from time to time by violent 

 revolutions and catastrophes. Cuvier argues that these took 

 place suddenly, from the evidence of the flesh carcasses of 

 mammalia in the gravels of Siberia, as well as from the 

 accumulations of pebbles and debris which are present at 

 certain horizons of the stratigraphical succession, and may be 

 assumed to indicate epochs of violent movement in the 

 former seas. Thus the development of organic life was 

 frequently interrupted by fearful catastrophes, which in the 

 earlier epochs extended over the whole surface of the globe, 

 but latterly became limited to smaller areas. Countless living 

 creatures fell victims to these catastrophes ; they vanished 

 for ever, and left only "a few remains scarcely recognisable by 

 the scientific investigator." 



A discussion of the natural 'forces which at the present day 

 affect earth-surfaces leads Cuvier to the conclusion that these 

 are not sufficient to explain the great revolutions of past 

 epochs in the earth's history. The present agencies of ice 

 and snow, running water and the ocean, volcanoes and 

 earthquakes, together with disturbing astronomical con- 

 ditions, are passed in review, for the purpose of demonstrating 

 the insufficiency. Then Cuvier recalls the often ridiculous 

 theories that philosophers and geologists invented in their 

 endeavour to arrive at some adequate explanation of the great 

 transformations of life and climate on the globe. He 

 recognises the value of the mineralogical work of Saussure 

 and Werner, but complains of the small share of attention 

 bestowed by these geologists and their contemporaries upon 

 fossils and the distribution of fossils in the rock-strata. Yet, 

 in his opinion, it is the study of the fossilised remains of 

 former faunas and floras which alone can give enlightenment 

 about the earth's past, the number and order of its revolutions, 

 and the history of creation. 



He regards the remains of four-footed animals as especially 

 valuable, since in their case the question whether they 

 belong to extinct or living genera and species can be more 

 definitely determined than in the case of the lower animals. 

 Even in the days of antiquity men knew fairly well all the kinds 



