263 



and lastly, sometimes in a gypsum * posterior to 

 the chalk. 



* Gypsum of the third formation among the secondary 

 gypsums. The first formation contains the gypsum, in which 

 are found the brine-springs of Thuringia, and which is placed 

 either in the Alpine lime-stone or zechstein, to which it essen- 

 tially belongs (Freiesleben, Geognost. Arbeiten, t. ii, p. 121.) 

 or between the sechstein and the lime-stone of the Jura, or 

 between the zechstein and the new sand-stone. It is the 

 ancient gypsum of secondary formation of Werner's school 

 (aelterer floezgyps), which we almost preferably call muriatU 

 ferous gypsum. The second formation is composed of fibrous 

 gypsum, placed either in the molasse, or new sand-stone, or 

 between this and the upper lime-stone. It abounds in com- 

 mon clay, which differs essentially from the salzthon or muri- 

 atiferous clay. The third formation of gypsum is more recent 

 than chalk. To this belong the bony gypsum of Paris ; and, 

 as appears from the researches of Mr. SiefFens (Geogn. 

 Aufsatsze, 1810, p. 142), the gypsum of Segeberg, in Hol- 

 stein, in which gem salt is sometimes disseminated in very 

 small nests (Jenaische JLitteratur-zeitung, 1813, p. 100). The 

 gypsum of Paris, lying between a cerite lime-stone, which 

 covers chalk, and a sand-stone without shells, is distinguished 

 by fossile bones of quadrupedes, while the Segeberg andLune- 

 bourg gypsums, the position of which is more uncertain, are 

 characterized by the boracits which they contain. Two 

 other formations, far anterior to the three we have just men- 

 tioned, are the transition gypsum (uebergangsgypsj of Aigle, 

 and the primitive gypsum ( urgypsj of the valley of Canaria, 

 near Airolo. I flatter myself, that I may render some service 

 to the small number of geologists, who prefer the knowledge 

 of positive facts to speculation on the origin of things, in 

 furnishing them with materials, from which they may gene- 

 ralize their ideas on the formation of the rocks in both herai- 



