﻿116 PKOF. E. W. SKBATS ON THE [Feb. I905, 



No. 12. About 300 feet below No. 11. 



This is a submarine calcareous tuff. Numerous fairly-large and 

 rounded fragments of a fine-grained decomposed basalt or melaphyre 

 occur. Lath-shaped crystals of plagioclase and irregular fragments 

 of magnetite are set in a brown structureless matrix, while steam- 

 cavities are lined or filled with low-polarizing chlorite. Two or 

 three basic types of basalt are present, some so dark in colour as to 

 be almost opaque ; others are much more felspathic, Avhile some 

 brown and almost isotropic palagonite-fragments occur. These are 

 enclosed in a matrix consisting partly of clear calcite, partly of 

 dolomite with regularly-arranged brown inclusions. The volcanic 

 fragments are in contact indifferently with dolomite and with 

 calcite. This association lends no support to the view that the 

 volcanic fragments constitute the source of the magnesium present 

 in the rock. 



No. 13. This specimen occurs below No. 12, at the foot of the 

 vertical cliff, and at the top of the talus-slope passed on the descent 

 of the mountain towards Bad Ratzes. 



The rock consists of a very fine-grained allotriomorphic dolomite, 

 and contains no recognizable organisms. 



/3. Rolled block from the stream, just above Bad Ratzes. 

 (See PI. XIII, fig. 2.) 



Dark-centred dolomite forms the bulk of the rock, and is arranged 

 in a meandrine way which suggests the former presence of corals. 

 The rock is cavernous, and the cavities have been lined by a 

 secondary deposit of clearer dolomite deposited from solution, and 

 showing alternate layers of clearer and more cloudy dolomite. 



No. 31. Summit of the Rosszahne. 



Much meandrine dark-centred dolomite is present, together with 

 later-formed, bigger and clearer dolomite-crystals. Some small 

 reddish fragments, possibly volcanic, are seen in the section. 



No. 27. ' Cipit- dolomite ' from a block on the Seiser Alp. 



A fine-grained rock, consisting mainly of idiomorphic crystals with 

 cloudy centres. Some of the rhombohedral kernels of the crystals 

 have been removed, either by solution or by grinding when making 

 the slice. A few reddish fragments occur, and are probably of 

 volcanic origin. 



Area of the Langkofl. 



No. 95. Fallen block from the eastern flank of the mountain. 



A rock which shows both concentric and radial structures in the 

 hand-specimen, but radiating crystals only in section. No idio- 

 morphic crystals are present. 



No. 94. Material lining the eastern flank of the mountain. 



A fragmental rock which, from its appearance and mode of 

 occurrence on the flank of the mountain, is suggestive of a reef- 

 talus. A dark calcareous cement embeds broken, idiomorphic, dark- 



