Structure of the Eastern Alps. 30? 



into conglomerate and g;reywacke slate, with subordinate calcareous beds full 

 of organic remains. Among- the fossils collected by ourselves from this locality 

 are the following : Producta hemisphcp-rica, Prodiicta latissima, a species 

 resembling Producta Martini, and a Pecten resembling a species in the trans- 

 ition series of Cork; to which we may add fragments of shells of the genus 

 Spirifer, Encrinital stems, &c. &c. 



These facts demonstrate, that transition rocks with organic remains are 

 not, as has been sometimes asserted, altogether wanting in the eastern Alps. 

 Of this error we ourselves partook before we visited the places above men- 

 tioned. A deposit full of organic remains, ranging through the very mine- 

 works of Carinthia, could not possibly have escaped notice; but in no memoir 

 with which we were acquainted had these very remarkable fossils been de- 

 scribed in such a way as to lead to any intelligible conclusion. 



After what has been stated we might perhaps affirm, that many parts of the 

 supposed primary axis are probably of the transition age, their present cry- 

 stalline texture having been superinduced by some cause which, with rare 

 exceptions, has obliterated the traces of their organic contents. In using the 

 terms primary and secondary, we merely endeavour to conform to the lan- 

 guage current among geologists. The two classes of rocks cannot, perhaps, 

 in any case be precisely separated from each other : and as far as regards the 

 central peaks of true granite, they may be of any age, and some of them are 

 probably among the most recent mineral masses of the chain. 



3. Red Marl, Sandstone, Magnesian Limestone, ^c, with subordinate beds 

 and masses of Gypsum, and more rarely icith brecciatcd Rock-salt and 

 Brine Springs. 



The great calcareous zones of the Alps often present enormous, bare, mural 

 escarpments towards the central axis, and in consequence the primary and 

 secondary systems of the chain are separated from each other by a succession 

 of deep longitudinal valleys. The waters collected from the central crests roll 

 down these valleys, till they meet with a great transverse cleft or fissure 

 (probably formed during some period of elevation), through which they escape 

 into the comparatively low regions on the outskirts of the chain. This phe- 

 nomenon is so general and striking as to force itself on the observation, and 

 has been noticed by almost every one who has written on the structure of the 

 Alps. 



The great calcareous precipices above mentioned do not however rest im- 

 mediately upon the transition rocks of the central region, but are separated 



2r2 



