ANNIVERSARY ADDRESS OF THE PRESIDENT. 



Ixxvii 



This marine fauna is supposed by Dr. Philippi and Dr. Sandberger 

 to be newer than that of Weinheim. Again, in the neighbour- 

 hood of Magdeburg marine formations occur in two locahties : — 

 1 st, the Westeregehi sands, which also overhe the brown coal ; and 

 2nd, the Magdeburg beds, which are considered identical with the 

 Septaria clay of Brandenburg and Berlin. Of these the Westeregeln 

 sands are considered the oldest. Septaria also occur in the blue clays 

 in the neighbourhood of Hesse Cassel underlying the bed of shelly 

 sand, evidently belonging to the same system. In my second paper 

 I have stated the reasons why I consider it not improbable that, not- 

 withstanding certain slight differences in the organic contents, these 

 three deposits of Magdeburg, Cassel, and Weinheim belong to one 

 formation, corresponding as nearly as possible with the Middle 

 Limburg beds of Belgium. They appear to mark the commence- 

 ment of a tertiary marine fauna in the North of Germany, and being 

 thus evidently the commencement of a system, I have been inclined 

 to look upon them as older Miocene rather than younger Eocene. 

 Our late President, in describing the youngest tertiary deposits in 

 the Isle of Wight, mentioned two facts, viz. that they rested con- 

 formably on the older Eocene deposits, and must therefore be taken 

 as a part of that formation ; and secondly, that some of the beds 

 contained the same organic remains as Avere found in the Weinheim 

 sands and marls. He consequently concluded that these Weinheim 

 beds must also be Eocene. Now it must be observed that the species 

 on which he founded this opinion are not strictly speaking marine, 

 but brackish-water species, principally Cyrena subarata and certain 

 forms of Cerithia, I hardly think that such evidence alone justifies 

 this conclusion. The species have a very considerable vertical range, 

 and hence it would perhaps be rash to argue on any contemporaneity 

 from them alone ; and, moreover, being brackish-water forms, it is 

 impossible to show any connexion between the aestuarine or brackish- 

 water areas at such a distance. A similarity in the condition of life 

 may have led to the appearance of these forms in different places at 

 dificrent epochs ; and it is therefore possible, notwithstanding the 

 identity of species, that the two brackish-water deposits of the Isle 

 of Wight and Weinheim may not be contemporaneous. But even if 

 they were so, we have every day brought before us additional evi- 

 dence to show that we must not look for those breaks or inter- 

 ruptions in the regular succession of strata, which are considered as 

 marking the transition from one formation to another, everywhere at 

 the same point. While local convulsions were causing an inter- 

 ruption in one district, the regular sequence of deposits was being 

 continued unbroken in another ; and thus the Eocene deposits may 

 have continued in the Isle of Wight for some time after those 

 changes in the relative level of land and sea had taken place, which 

 in the North of Germany marked the commencement of the Miocene 

 epoch. We may therefore have here one of those anomalous de- 

 posits between two hitherto supposed distinct formations, combining 

 some of the characteristic features of each, and which must be con- 

 sidered as marking the transition from the one to the other. 



