20 DIENER : GEOLOGICAL STRUCTURE OF CHfTICHUft 



the Spiti shales, which surround the Tibetan crags. The condition of 

 the sediments remains unaltered over a large area, and is not influ- 

 enced in any distinct way by the vicinity of the crags. The nature 

 of the Spiti shales themselves as well as of their organic remains 

 prove, that they must not be considered either as a pelagic nor as 

 a littoral formation. Professor Uhlig, who is working out the fauna 

 of the Spiti shales, has kindly forwarded the following notes on this 

 subject :— 



"The Spiti shales are certainly not littoral sediment, as for 

 instance is the Carpathian ' Klippenhulle,' i.e., the complex of rocks 

 in the immediate vicinity of the Carpathian Klippen (red clay, sand- 

 stones, and conglomerates with Inoceramus). With regard to their 

 lithological character, the Spiti shales are undoubtedly very similar to 

 the * Terrain a geodes ' (Dogger) of the Caucasus and to the Werns- 

 dorf and upper Teschen beds of Silesia. In the latter beds the iron 

 occurs in layers, but is not concentrated in concretions. In the 

 Wernsdorf beds remains of terrestrial plants are frequently met with ; 

 their presence in connexion with the clastic condition of the sedi- 

 ments seems to prove that the latter are not truly pelagic deposits. 

 The same reasoning might be applied to the origin of the Spiti shales. 

 In this respect the fact is of some importance, that the state of 

 preservation of the very numerous ammonites completely excludes 

 the possibility of their having been rolled or abraded near an ancient 

 coast-line. As in the Wernsdorf beds, specimens with entirely pre- 

 served mouthborders (peristomes) are not at all rare. Their state of 

 preservation is indeed so perfect that they cannot be supposed to 

 have been rolled or damaged in any way. The Spiti shales ought 

 therefore to be considered as sediments, which, having neither been 

 deposited in the vicinity of the ancient coast-line nor in the open 

 sea, are certainly not littoral, though not strictly thalassic." 



The difference in the stratigraphical sequence between the main- 

 region of the sedimentary belt of the Central Himalayas and the 

 Tibetan crags of the Chitichun area is equally consistent with an 

 ( 20 ) 



