142 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 3, 



between the extensive Brown-coal deposits which (notwithstanding 

 the ingenious hypothesis of a German author*, who attempts to 

 show how these vast accumulations of vegetable matter were depo- 

 sited in the sea) I am disposed to consider as formed on the spot 

 where the plants originally grew, and consequently as a freshwater 

 formation, raised perhaps only slightly above the level of the ocean, 

 like the now existing cypress-swamps of Louisiana or the turf-mosses 

 of more northern regions. 



Brown-Coal Deposits. — I am thus led, before concluding these 

 remarks, to add a few words respecting the various deposits of Brown- 

 coal in the north of Germany, which are connected with the tertiary 

 formations here alluded to. I am aware that there are many other 

 deposits deserving notice, but this subject is too extensive to be fully 

 considered at present. It is true that independently these Brown- 

 coal deposits are not in themselves so conclusive as to geological 

 epochs, in consequence of their not being necessarily so intimately 

 connected with each other as is the case with true marine deposits. 

 Still, when we can ascertain their age relatively to marine beds, we 

 are enabled to come to some conclusion respecting their successive 

 ages. 



Brown-coal deposits occur in all the three distinct localities to 

 which we have alluded in this paper, viz. — 1. In the Mayence basin 

 are two distinct deposits ; first, between the true Marine-Sands of 

 Weinheim and the overlying Cerithium and Littorinella limestones, 

 and secondly, between the Littorinella limestone and the leaf-bearing 

 sandstone. 2. In the Hesse Cassel deposit the great Brown-coal 

 beds underlie the Marine Fauna. And 3. In the plains of the north 

 of Germany there are again two distinct Brown-coal deposits ; first, 

 under the Westeregeln Sands near Magdeburg ; and secondly, above 

 the Septaria-clay of the Mark Brandenburg. Of these, the bed 

 which underlies the Westeregeln Sands is unquestionably the oldest. 

 That of Brandenburg may be contemporaneous with one of the 

 Mayence basin deposits ; but there is no direct evidence of the fact. 

 We have thus Brown-coal deposits of at least three, if not four, di- 

 stinct periods. That of Cassel is probably contemporaneous with 

 that of Magdeburg. 



The upper Brown-coal deposits of the Wetterau have been con- 

 sidered as of the same age as those of the upper Cyrena-marl. I 

 am, however, disposed to think, from the observations of D. Lud- 

 wig of Nauheim, which I have only lately had an opportunity of 

 perusing, that they must belong to a still younger period. They 

 are described as occurring in hollows of decomposed basalt at 

 Laubach, Salzhausen, and Berstadt, near the western limits of the 

 great basaltic formations of the Vogelsberg. They rest upon or are 

 imbedded in vast deposits of clay, derived from the decay, in situ, of 

 the basalt itself, and are consequently posterior, not only to the 

 basalt, but even to its decomposition, therein differing from the 

 Brown-coal of the Westerwald, which has been elevated and broken 

 up by the protrusion of the basaltic masses. 



* Zeitschrift der Deutschen Geol. Gesellsch. vol. iji. p. 217. 



