Structure of the Austrian Alps, fyc. 95 



It remains for us to notice the sections on the right bank of 

 the Inn, through the red sandstone series ; especially as we 

 have there a good exhibition of that expanded portion of it 

 which contains great subordinate beds of limestone. We 

 have in a former paper noticed the masses of red marl, red 

 sandstone, and conglomerate, which on the right bank of the 

 Inn rise from beneath the Alpine limestone and form the 

 support of the unconformable tertiary deposits of Ha'ring. 

 The sandstone passes, near the coal-works, into a very close- 

 grained, thick-bedded, micaceous rock ; and alternates with 

 masses of limestone resembling rauchwacke, some of which 

 are bituminous and extremely fetid. From this place to 

 Schwatz (a distance of more than two posts), there are, on the 

 right bank of the Inn, a great succession of sections show- 

 ing alternations of fetid limestone and red marl or sandstone*. 



South- 

 marls and reddish gray calciferous grits. By following these on their rise 

 towards the north-east, they are found to repose upon a sandstone, which 

 passes downwards into a recomposed porphyry, and finally into a coarse 

 conglomerate. This conglomerate at Lugano is seen to rest against the 

 mountain masses of crystalline porphyry, from which it has been derived, 

 and to which it appears to have precisely the same relations as the older 

 conglomerates of Foyers, Trefad, and the Ord of Caithness, have to the 

 granitic and syenitic rocks of the Highlands. (See Geol. Trans. 2d Series, 

 vol. hi. p. 139.) 



In an ascending order, these conglomerates, graduating into sandstones 

 and grits, exhibit in one part a fine-grained whitish grit, like some of the 

 best freestone of the Scotch coal-measures ; and these beds contain im- 

 pressions and detached portions of plants, and thin laminae of carbonaceous 

 matter. The red marls and red sandstone which succeed, immediately 

 support the Alpine limestone of Monte Cislone; and the highest members 

 of that mountain assume the prevailing dolomitic aspect and shivery struc- 

 ture of all the peaks of Alpine limestone in this part of the Tyrol. The 

 same relations of red sandstone, marls, and grits, supporting the Alpine 

 limestone, are seen well exposed in the adjoining valleys of Avisio and 

 Fassa, wherever the general range and structure of these formations is 

 not obscured by the trap dykes abounding in that region, many of which 

 have a syenitic and granitic character. In the higher part of these val- 

 leys, and particularly near Predazzo, these dykes frequently burst through 

 the regular strata, which in many instances are altered in their mineral 

 character, dislocated, and frequently overwhelmed by bulging masses 

 of the igneous and intrusive rocks. At the Canzocoli, the Alpine lime- 

 stone in contact with the trap, is changed into a crystalline, white marble, 

 which is now quarried for statuary purposes ; the edges of the limestone 

 presenting bands of serpentine, and the whole forming a beautiful and di- 

 rect analogy to the altered lias (described by Dr. Macculloch) in the Isle of 

 Skye, where that deposit comes into contact with syenite. 



The red sandstone and marl which have been derived from the pre-exist- 

 ing porphyry, and which so uniformly support the Alpine limestone, con- 

 tain subordinate protuberances of anhydrite and gypsum near Cavalese ; 

 and the rock-salt, recently discovered in the adjoining valley, is probably 

 subordinate to the same deposit. 



* The transverse section from Haring to Schwatz makes a very acute 



angle 



