242 THE HISTORY OF GEOLOGY 



movement of subsidence such as Hutton considered was 

 affecting islands and continents at the present day. 

 Would we account for the marine sediments of which our 

 land consists, we have but to turn our eyes to the rivers 

 constantly bearing their burden of mud into the sea, 

 where it is spread abroad in strata precisely similar to 

 those of the remote past. As strata are formed now, so 

 have they always been formed ; as lands rise and fall now, 

 and seas pass imperceptibly into continents, and con- 

 tinents into seas, so they have always done in the past. 

 But how slowly all these changes proceed ! A human 

 lifetime is not long enough to witness any appreciable 

 effect. In this period the thickness of stratified material 

 laid down by a river in the sea would not amount to more 

 than a few inches, and the rocks of the earth's crust are 

 many thousands of feet in thickness. Well might the 

 stoutest-hearted be appalled before the vast aeons of time 

 which Hutton conjured up before the imagination ! Not 

 so Hutton ; having broken the narrow bonds of time 

 previously imposed upon our science, he revelled in excess 

 of freedom, and declared that the duration of our planet 

 was practically infinite ! 



How was this new teaching received in Oxford ? 



The title of a work by Dr. Kidd, who was Professor of 

 Chemistry in 1803, will inform us. It runs as follows : 

 "A Geological Essay on the Imperfect Evidence in Support 

 of a Theory of the Earth, 1815 " ; and the book itself con- 

 cludes with the assertion that " ancient strata cannot be 

 explained by existing causes : that the Science of Geology 

 is so completely in its infancy as to render hopeless any 

 attempt at a successful generalisation." In this opinion 

 I believe Dr. Kidd to have been in sound agreement with 

 the teaching of the leading geologists of the day; his 

 work is by no means aggressive, and might rather be 

 regarded as a text-book than a polemic ; as a text-book it 



