Struchire of the Eastern Alps. 315 



lower level than No. 8. of the existing- section, so long- as the present mode 

 of working- the mines is continued*. 



The salt mass here, as well as at Ischel, Aussee, Hallein, &c., is a hreccia 

 of saliferous clay and gypsum, separated from the surrounding, grey limestone 

 by an envelope of blue, gypseous shale. The highest galleries, 1, 2, and 3, 

 traverse the salt mass completely, and reach the overlapping limestone of 

 the Blossen ; but the extent of the range of the deposit beneath that mountain 

 is unknown, as the remaining five galleries terminate in the salt without 

 piercing through it. On whatever side of the works the broken rocky region 

 be examined, there are no traces of red sandstone, not even in gorges more 

 than one thousand feet beneath the lowest gallery ; on the contrary, nothing- 

 is seen at the base of the mountain except compact, Alpine limestone. 



By comparing the previous account with what we have already published, 

 it appears, that the salt deposits of Hall, Hallein, Halstadt, Ischel, and Aussee, 

 occur nearly under the same circumstances ; being- all associated with great, 

 insulated masses of brecciated marl and sandstone, rolled up and encased 

 among- contorted beds of Alpine limestone f. As they are entirely separated 

 from each other, it would be impossible to prove, without a much better series 

 of organic remains than we have yet seen, that they are all exactly on the same 

 parallel : but we have no hesitation in so far adopting- the system of M. de Lill, 

 as to place them in the middle division of the Alpine limestone series. 



In the limestone beds associated with these insulated masses of saliferous 

 breccia are indeed many fossils, few however which are well preserved : 

 among them are Orthoceratites, and Ammonites of which the concamerations 

 are marked by simple or undulating lines : both might seem to indicate strata 

 older than any part of the oolitic series : but along with them are true Ammo- 



* The process employed here (and we believe in all the Austrian salt mines) is, to excavate a 

 chamber in the saliferous mass, and then to fill it with water. All issue being completely closed, 

 the chamber is left in this condition for several months, during which the water gradually dissolves 

 the saline matter, whilst the associated clay and gypsum fall to the bottom and form a sediment. 

 When fully saturated, the brine is let out, and conveyed by pipes to evaporating. houses in the 

 neighbouring valleys, where the water is driven off by the heat of furnaces fed by wood from the 

 pine forests. From the works of Halstadt the saline solution is transported to so great a 

 distance, previous to evaporation, that the channel of conveyance necessarily commences at a 

 considerable height above the level of the lake. 



-j- We believe that our published plate (Phil. Mag. and Annals, N.S., vol. viii. pi. 2. fig. 2.) 

 correctly represents the position of the salt of Hallein ; the error, alluded to in a previous note, 

 was in connecting the Hallein system with that of the Untersberg. They are separated accord- 

 ing to our present views by an enormous derangement, w hich brings in the lower Alpine limestone 

 a second time at the Untersberg. See Plate XXXVI. fig. 9. 



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