CATASTROPHISM 3 5 I 



others, while the records may be scanty, interrupted, confused, 

 unintelligible, even misleading and falsified, so that it is no easy 

 task to write history accurately and without attributing undue im- 

 portance to this or that principle or policy. 



These considerations fully apply to geological history ; its divi- 

 sions are founded upon the rise and culmination of great groups 

 of animals and plants, which one after another have risen to pre- 

 dominance and then declined, their place being taken by others 

 better fitted for the new conditions. These successive culminations 

 are not sudden, but gradual and continuous, and the beginnings 

 of each group are to be found in time long before the period of 

 its predominance. Nor is decline immediately followed by extinc- 

 tion; one group slowly gives way to another, but long after the 

 first has ceased to be the principal fact in the world's life, it may 

 linger on in diminished importance until, perhaps, it finally dis- 

 appears. The geological periods, therefore, like historical periods, 

 had not definite beginnings and endings, for one slowly fades into 

 another, but they are none the less actual because the lines of 

 separation between them must often be somewhat arbitrarily 

 drawn, and they cannot always be made to correspond in differ- 

 ent regions. 



In geology, as in history, we must distinguish between the events 

 and the records of them. The more complete the records, the 

 more obviously continuous and gradual was the course of events ; 

 only imperfect records can make the history seem broken and dis- 

 jointed. As our science was first developed in western Europe, 

 where the great groups of strata are mostly separated by uncon- 

 formities, with abrupt changes in the fossils, the older geologists 

 very naturally concluded that the great divisions of geological time 

 were marked by frightful catastrophes which devastated the earth, 

 destroying every living thing upon it. Each group of rocks was 

 looked upon as the product of a long and tranquil period, and its 

 fossils were believed to represent an entirely new creation. Though 

 opposed by some far-seeing minds, the doctrine of Catastrophism, 

 as it was called, long held sway, but was shown to be erroneous, 

 when the study of geology was carried to other parts of the world. 



