SEQUEL TO SYSTEMATIC GEOLOGY. 585 



discovered in our geological series. " Such a coin- 

 cidence," he observes", " in the subdivisions of two 

 distant mechanical deposits, even upon the supposi- 

 tion of their being strictly contemporaneous, is truly 

 astonishing. It has not been assumed hypotheti- 

 cally, but is the fair result of the facts which are 

 recorded in this paper." 



As an example in which the study of geological 

 equivalents becomes still more difficult, we may 

 notice the attempts to refer the strata of the Alps 

 to those of the north-west of Europe. The dark- 

 coloured marbles and schists resembling mica slate 10 

 were, during the prevalence of the Wernerian the- 

 ory, referred, as was natural, to the transition class. 

 The striking physical characters of this mountain 

 region, and its long-standing celebrity as a subject 

 of mineralogical examination, made a complete sub- 

 version of the received opinion respecting its place 

 in the geological series, an event of great impor- 

 tance in the history of the science. Yet this was 

 what occurred when Dr. Buckland, in 1820, threw 

 his piercing glance upon this district. He immedi- 

 ately pointed out that these masses, by their fossils, 

 approach to the oolitic series of this country. From 

 this view it followed, that the geological equivalents 

 of that series were to be found among rocks in 

 which the mineralogical characters were altogether 

 different, and that the loose limestones of England 



9 GeoL Trans. Second Series, iii. 121. 

 1(1 De la Beche, Manual, 313. 



