554 Dr. C. Siruclimann — The Jura of Hanover and England. 



Upper Jurassic formations of different regions is rendered very mucli 

 more difficult by the fact that almost everywhere with the Kimmer- 

 idge the development of local faunas commences, and the species are 

 very differently distributed in the different zones. This appears very 

 prominently in the comparison of the higher beds of the Upper 

 Jurassic in England and Hanover. 



The Upper Kimmeridge Clay in England contains a fauna so 

 completely different from that of the North-German Kimmeridge, 

 that hitherto only two fossils have been determined which also 

 belong to the Hanoverian Jura, namely, Exogyra virgula and Ger- 

 villia tetragona, species found both in the Middle and Upper 

 Kimmeridge. Nevertheless, as follows especially from the fol- 

 lowing statements, it cannot be doubtful, that the Upper Kimmer- 

 idge Clay and the Hanoverian Upper Kimmeridge (Virgula beds) 

 were deposited at about the same time. 



8. To estimate correctly the reciprocal relations of the English 

 and Hanoverian Portlandian beds, I have to call attention to the fact 

 that, according to my recently published investigations on the Hano- 

 verian Wealden,' the English and North-German Wealden deposits 

 have been developed in a perfectly concordant manner. In both 

 districts the uppermost horizon is occupied by the Weald Clay 

 (Upper Wealden), which is certainly considerably more strongly 

 developed in England, so that the Wealden period there probably 

 had a longer duration than in North Germany. Below the Weald 

 Clay lies the Hastings Sand (Middle Wealden), which in turn over- 

 lies the Purbeck Beds (Serpulite or Lower Wealden). The assumed 

 parallelism is borne out both by the conditions of stratification and 

 by the distribution of organic remains in the different divisions. In 

 England the Purbeck beds rest immediately upon the Portland Stone, 

 and the latter on the Portland Sand ; below this follows the Upper 

 Kimmeridge Clay. In Hanover, on the other hand, taking the re- 

 versed order, the Upper Kimmeridge (FiVgfwk-beds) is immediately 

 overlain by the beds with Ammonites gigas (i.e. the Lower Portland) ; 

 these are followed regularly by the Eimbeckhiiuser Plattenkalke {i.e. 

 the Upper Portland), which again are covered by the M under 

 Mergelen, and finally comes the Serpulite, which undoubtedly 

 represents the English Purbeck. Necessarily, therefore, the de- 

 posits between the Kimmeridge and the Purbeck must be of the 

 same age as the English Portland Stone and Portland Sand, 

 whether we refer the transiticm stage between the Eimbeckbiiuser 

 Plattenkalke and the true Purbeck (i.e. the Miinder Mergel) to 

 the Portland or the Purbeck. The supposition entertained by 

 some authorities that the English Portland formations are entirely 

 unrepresented in North Germany is therefore certainly an error, 

 due solely to the circumstance that the English and Hanoverian 

 Portland formations assume an entirehj different phase of development, 

 as indeed frequently happens in the Upper Jura. This circumstance 

 must not be left out of consideration in comparing the English and 

 Hanoverian Portland faunas. 



1 Die 'Wealden-Bilduiigen d. Umg. v. Hannover, pp. 115, et seqq. 



