Structure of the Austrian Alps, §c. 101 



galleries have been opened in it at the height of 4480* Vienna 

 feet above the level of the sea: but, like all the other corre- 

 sponding deposits, it appears soon to thin out, so as not to be 

 continued through the neighbouring mountains. The brec- 

 ciated saliferous mass is surmounted by three beds of the united 

 thickness of fifty feet. The lowest (c) is chiefly composed of 

 marl; the middle bed (b) of gypsum; and the highest (a) con- 

 sists chiefly of a gray and white concretionary limestone, the 

 nuclei of the concretions being often composed of small Tere- 

 bratulae. To this rock the term rogenstein has been applied, as 

 well as to the singular concretionary magnesian rock near 

 Schwatz {supra, p. 96); but they both differ essentially, in their 

 structure and relations, from the rogenstein of the Hartz, which 

 is a coarse oolite subordinate to the new red sandstone. Over 

 these beds come the upper strata of limestone containing many 

 fossils; among which we recognized Ammonites, Belemnites, 

 Buccinites, Pectens, Terebratulse, Sic. &c. 



The whole of the beds here described, both from their 

 position in the chain and from their fossils, belong evidently 

 to the middle system of Alpine limestone; and notwithstanding 

 the brecciated structure of the saliferous mass, they seem to be 

 less disturbed than in the other analogous deposits of theAlps. 



(2.) Salt formations of Berchtolsgaden and Hallein. — These 

 two deposits, though very near together, are not continuous; 

 probably in consequence of the great dislocations and contor- 

 tions of the neighbouring portions of the chain. The relations 

 of the salt mass of Hallein are extremely clear and may be seen 

 even in our very reduced section (PI. II. fig. 2). It is in a len- 

 ticular form, being about 1520 toises in length, 600 in breadth, 

 and 220 f toises in its greatest thickness ; and it is imbedded, or 

 rather enclosed, in the contorted strata of limestone. The 

 limestone below the salt is thin-bedded and compact; in colour 

 gray, red, or variegated ; alternates with bands of green and 

 red marls, and contains here and there considerable portions 

 of chert. It is surmounted by dark-coloured, gypseous marls 

 which form the lining of the salt deposit |. The saliferous 

 masses are made up of green, red, and variegated gypseous 

 clays, much mixed with brecciated masses of red micaceous sand- 

 stone, and with fragments and concretionary masses of dark-co- 

 loured limestone. The whole system is surmounted by twisted 

 beds of light-gray, compact limestone, some of which contain 

 many fossils. These relations are proved, not only by the 



* 46/2 English feet. f 9722, 3837, and 1407 English feet. 



X In the galleries through the dark- coloured gypseous marls there is an 

 extraordinary efflorescence of sulphate of magnesia. 



general 



