1 84 



NATURAL SCIENCE. 



March, 



and Pethathali encamping ground above Silakank (19,265 English 

 feet), to^Sirkia River in Hundes ; a complete section from (Cambrian ?) 

 Haimantas to the Gieumal Sandstone (Cretaceous), without a great 

 discordance, gives, according to Dr. Griesbach : — 



Haimantas 

 Lower Silurian 

 Upper Silurian 

 Devonian.. 

 Carboniferous 

 Permian and Trias 

 Lias and Spiti Shales 

 Gieumal Sandstone 



3,000 — 4,000 feet. 

 200 

 1,100 ,, 



700 

 1,200 — 1,400 ,, 

 3,600 — 3,900 ,, 



1,400? 

 1,200 — 1,500 ,, 



12,400 — 14,200 feet. 



The determination of the thickness of the Spiti Shales and Gieumal 

 Sandstone is difficult, because these less-resistent beds are crumpled 

 into local folds. 



A parallel section across the Kurkutidhar range (Chor Hoti, 

 about 18,000 feet), Shalshal encamping ground and Shalshal Pass 

 (16,390 feet) to Hundes gives, without the Haimantas : — 



9,400 — 10,100 feet. 



These figures show that a great and deep ocean has been incorporated 

 into the continent, and that the deposits of this ocean form part of the 

 highest mountain ranges. 



It may be remarked that within the eastern Alps Mesozoic lime- 

 stones of different ages contain deep-water radiolarian chert. But 

 the great and well-bedded masses of white Rhaetic limestones of 

 Austria betray distinct proofs of a continuous rising of the shore-line. 

 It is also true that certain bright red enclosures within these white 

 limestones seem clearly not to be red deep-sea clay, but true terra rossa, 

 formed by atmospheric decomposition of the limestone ; so that these 

 beds must have formed reefs in the ocean. Therefore it is at present 

 difficult to say whether in the Alps the Tethyan Ocean did at any 

 time attain the total depth of, say, 2,000 fathoms ; or whether deposits 

 followed so rapidly and depression was so continuous that this was 

 not the case. 



The later Tethyan history, the recapitulation of the vicissitudes 

 which led to the formation of the existing Mediterranean, forms 

 certainly one of the most attractive chapters of historical geography. 

 Marine deposits of Mediterranean type (Erste Mediterranstufe, 

 Miocene inferieur) enter the Rhone Valley, surround the present site 



