﻿Vol. 6l.] DOLOMITES OF SOUTHERN 1YR0L. 123 



Buchenstein Limestone. 



No. 18. A hard compact rock, interbedded with a siliceous nodular 

 limestone, above Bad Ratzes. 



The groundmass of the rock-section consists of structureless 

 calcite, in which various organisms occur. These appear to be 

 dolomitized, since they are not stained with Lemberg's solution. 

 The most abundant form is long and curved, and probably re- 

 presents cross-sections of thin-walled shells. Some of the bodies 

 are somewhat oval, and may represent tangential sections of shells. 

 Cross-sections of minute tubules are also present, and a section of 

 a foraminifer is to be seen as well. One crystal of biotite was 

 recognized in the slide. 



Analysis shows that only 3*4 per cent, of magnesium-carbonate 

 is present in the portion analysed ; but examination of the rock- 

 section shows that the amount present in places must be considerably 

 in excess of the figure obtained by analysis. 



No. 88. Nodular limestone from the Gader Gorge, north of 

 St. Leonhard. (See PI. XII, fig. 1.) 



The rock has a granular matrix of calcite, in which various 

 organisms preserved in calcite are embedded. These include a 

 rotaline foraminifer, shell-sections, calcareous algae, and other 

 meandrine bodies, the precise nature of which cannot be determined. 

 Along cracks the limestone has been altered by infiltrated water 

 bearing salts of iron and magnesium ; and as a consequence, pyrite, 

 chalybite, and dolomite have been deposited in the immediate 

 neighbourhood of the fractures. 



The dolomite-crystals are all zoned, and most of them consist of 

 alternate layers of dolomite and chalybite, although staining shows 

 that some of the crystals consist of alternate zones of dolomite and 

 calcite. 



Mendola Dolomite. 



No. 19. Above Bad Batzes, and below No. 18. 

 A compact dolomite, consisting entirely of allotriomorphic crystals, 

 showing no trace of organic structure. 



Lower Muschelkalk. 



No. 86. Gader Gorge, north of St. Leonhard. 



The groundmass consists of calcite-crystals, some of which are 

 twinned. Sections of shells are numerous ; many angular quartz- 

 grains occur ; while some flakes of muscovite and one or two crystals 

 of decomposed pyrite are also to be seen. 



Above the Schlern Dolomite. 

 Dachstein Dolomite. 



No. 1. From the summit of the Schlern (8400 feet). 



A dolomite composed of allotriomorphic crystals. The only 



