Ixiv 



PROCEEDINGS OP THE GEOLOGICAL SOCIETY. 



convulsions which were constantly going on — sometimes here and 

 sometimes there — over the whole surface of the earth. It is, how- 

 ever, comparatively only a small portion of the Franconian region 

 which took part in these changes during the Tertiary period ; hut the 

 new formations are of so gigantic a character that they make up in 

 intensity for what may be wanting in extent. To these phenomena 

 belong the volcanic formations, which were developed within the dis- 

 trict of the Ehon mountains ; they form a link in that great chain of 

 volcanic operations which connects the central mountains of Bohemia 

 through the Fichtelgebirge on the one hand, and through the Yogelsge- 

 birge and the Wester wald on the other, with the Siebengebirge. 



Dr. Waagen has endeavoured in a short memoir to give us a general 

 classification of the beds of the Upper Jurassic formation, taking as 

 his basis the classification of English geologists, as the first which 

 was founded on a more accurate knowledge of the diiferent beds, 

 although he doubts whether the names which were sufficiently 

 appropriate in the localities to which they were originally applied, 

 are equally so when applied to large areas where the same beds either 

 assume a diff'erent petrographical fades or are characterized by a 

 distinct or abnormal fauna. After describing the various local hori- 

 zons from the Portland Stone to the Oxford Clay, he endeavours to 

 establish a comparison between the English beds and those on the 

 continent, which are assumed to be their representative zones. The 

 following table shows how he groups these formations : — 



i 



§ 



1 



Local Horizons. 



English Divisions. 



Zone of Trigonia gihhosa . . 



r 1. Portland Stone. 

 \2. Portland Sand. 



Eegion of 

 Orhicula latissima and 

 Acanthoteuthis speciosa . . 



)>3. Kimmeridge Clay. 



Eegion of 

 Ammonites mutabilis and 

 Exogyra virgula 



Eegion of 

 Ammonites alternans and 

 Rhynchonella inconstans 



Eegion of 

 Cidaris fioiigemma 



f 4. Upper Calcareous Grit. 

 \ 5. Oxford Oolite. 



Eegion of 

 Ammonites MarteUi 



\ 6. Lower Calcareous Grit. 



Eegion of 

 Ammonites hiarmatus .... 



} 7. Oxford Clay. 



