1854.] HAMILTON — MAYENCE BASIN. 297 



lived upon their banks. These remains, in certain favourable spots, 

 have been heaped together in such abundance as to have obtained for 

 those formations in which they are found the name of " freshwater 

 limestone," At the same time, on the western shores of the lake, 

 between Kreuznach and Diirckheim, it is probable that the saline cha- 

 racter of the water was maintained by those abundant salt-springs, 

 which, even in the present day, issue from the neighbouring rocks, 

 bringing health and wealth to the surrounding population, and 

 giving evidence of that secret and subterranean activity which in one 

 form or another has at all periods and in all places modified the 

 crust of our globe. 



"We have seen that during this period calcareous rocks were de- 

 posited to a great extent in this northern portion of the upper 

 Rhenish lake. From whence was this calcareous matter derived? — 

 and why should it have been mainly deposited in this portion of the 

 basin ? It appears to have been owing to one, if not to both, of the 

 following causes. It may have been deposited from local springs 

 highly charged with calcareous matter, or it may have been derived 

 from the material brought down by the many rivers which flowed into 

 the lake ; and its deposition in this particular spot may have been 

 partly brought about by the greater amount of animal life living in 

 this still brackish water, to whose existence and growth this calca- 

 reous matter was subservient ; or partly, perhaps, by some chemical 

 influence, the result of the action of the salt-springs upon the 

 water thus charged with calcareous matter. But, that it has in 

 some places at least owed its origin to calcareous springs of a 

 local character, is I think sufficiently proved by the structure of 

 the rock itself. I need only refer to fig. 10. p. 269, where the 

 hard portion of the limestone rock, evidently formed contempora- 

 neously with the softer and more sandy beds to the S.E., containing 

 the intercalated beds with Venus incrassata, is altogether made up 

 of a congeries of hollow pipes and stems, as if it were the remains of 

 a mass of incrustations around the delicate fibres of mosses or con- 

 fervse. A similar structure may also be seen in many other localities, 

 particularly along the line of limestone cliffs to the S.W., in the 

 neighbourhood of Diirckheim and Kahlstadt ; and, wherever this 

 occurs, the limestone itself is spongy and cavernous, full of small 

 irregular cavities, and frequently containing nuclei of a harder and 

 more solid texture. 



Other changes subsequently took place, which we can now hardly 

 stop to consider. \w some parts of this lacustrine basin the calca- 

 reous beds were covered up by morasses and forests, as in the 

 Wetterau and the Westerwald. A description of the fossil flora of this 

 district would be a subject of great interest, for amongst the curious 

 relics of the period which have been rescued from the Brown-coal 

 of the Wetterau are perfect specimens of more than one species of 

 Vine, the fruit itself being preserved in the form of petrified raisins*. 

 These forests and morasses were subsequently converted into 



* See Official Report of the 29th Meeting of the Society of German Naturalists 

 at Wiesbaden, 1853, p. 155. 



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