THE STORY OF NINETEENTH-CENTURY SCIENCE 



But to deny catastrophism was to suggest a revolu- 

 tion in current thought. Needless to say such revolu- 

 tion could not be effected without a long contest. For 

 a score of years the matter was argued pro and con, 

 often with most unscientific ardor. A mere outline of 

 the controversy would fill a volume ; yet the essential 

 facts with which Lyell at last established his proposi- 

 tion, in its bearings on the organic world, may be epito- 

 mized in few words. The evidence which seems to tell 

 of past revolutions is the apparently sudden change of 

 fossils from one stratum to another of the rocks. But 

 Lyell showed that this change is not always com- 

 plete. Some species live on from one alleged epoch 

 into the next. By no means all the contemporaries 

 of the mammoth are extinct, and numerous marine 

 forms vastly more ancient still have living represent- 

 atives. 



Moreover, the blanks between strata in any particular 

 vertical series are amply filled in with records in the 

 form of thick strata in some geographically distant 

 series. For example, in some regions Silurian rocks are 

 directly overlaid by the coal measures ; but elsewhere 

 this sudden break is tilled in with the Devonian rocks 

 that tell of a great " age of fishes." So commonly are 

 breaks in the strata in one region filled up in another, 

 that we are forced to conclude that the record shown 

 by any single vertical series is of but local significance 

 telling, perhaps, of a time when that particular sea-bed 

 oscillated above the water-line, and so ceased to receive 

 sediment until some future age when it had oscillated 

 back again. But if this be the real significance of the 

 seemingly sudden change from stratum to stratum, then 

 the whole case for catastrophism is hopelessly lost ; for 



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