﻿Vol. 6 1.] 



DOLOMITES OF SOUTHERN TYROL. 



109 



Lower Muschelkalk. 



Only one analysis was made from this horizon, the specimen 



(No. 86) being taken from the 



OaC0 3 . I Mg0O 3 . ! Eesidue. I Gader Gor g e in tne Yalle y of 

 No. p er cent] Per cen t. \ Per cent. Abtei - Jt Wl11 be noticed that 

 86 56-6 12-2 j 31-20 | the rock contains comparatively- 

 little magnesium-carbonate, but 

 much insoluble residue. 



Analyses from Beds above the Schlern Dolomite. 



Succeeding the Schlern Dolomite is a deposit of variable character, 

 marls containing gypsum, coral-limestones, or dolomitic rocks. 

 They are known as the Baibl Beds, are usually iron-stained, and 

 are never of any great thickness. Following these comes a great 

 thickness of limestones or dolomites, usually of a bedded character, 

 known as the Dachstein Beds. These form the uppermost 

 beds of the Trias, corresponding in age to the BhaBtic deposits, and 

 they are in some places more than 3000 feet thick. 



Dachstein Dolomite. 



No. 1 is from the summit of the 



Schlern. 

 No. 42 from the southern flanks of 



Monte Cristallo, below Tre 



Oroci. 

 No. 61 from the Val de Travernanzez, 



west of Monte Tofana. 

 No. 104 from the western end of 



Sett Sass. 



In each case the specimens were collected from the base of the 

 deposit, immediately above the junction with the red Baibl Beds. 

 It will be noticed that the base of the deposit is a dolomite of very 

 great purity and approaching the theoretical composition. 



The Dachstein Beds are not always so devoid of insoluble residue, 

 for Profs. Dcelter & Hoernes x record two analyses of dolomites 

 containing respectively '67 and -98 per cent, of residue, the first from 

 the summit of Pordoi (south of Monte Sella), the second from the 

 Fanis Alp. 





CaC0 3 . 



MgC0 3 . 



Insol. res 



No. 



Per cent. 



Per cent. 



Per cent. 



1.. 



56-5 



434 



•07 



42... 



60-4 



39-6 



trace. 



61... 



58-7 



41-3 



•013 



104... 



54-8 



45-2 



trace. 



Baibl Beds. 



No. 4 is from the Schlern plateau, just below Burgstall ; while 



No. 73 is from below the 

 military post on the western 

 flanks of the Diirrenstein, 

 above the Seeland Alp. In 

 each case the amount of in- 

 soluble residue present is considerable. 



1 Jahrb. d. k.-k. geol. Eeichsanst. vol. xxv (1875) pp. 322, 323. 





CaC0 3 . 



MgC0 3 . 



Insol. res. 



No. 



Per cent. 



Per cent. 



Per cent. 



4 ... 



52-8 



43-6 



3-534- Fe 2 



73 ... 



68-1 



28-2 



3-66 



