THE KAMPA SYSTEM. 
47 
Although the upper and lower limits of the Cretaceous system 
of Central Tibet can be approximately determined, it is at 
present impossible, owing to the absence of fossils from the beds 
both at the top and at the base, to define its exact boundaries. Nor 
is it possible to attempt to identify the sub-divisional units recognised 
in the Cretaceous of Europe. When the specimens collected at Kampa 
dzong and at Tiina have been worked out in detail, many of the 
European zones will no doubt be recognised, but it is not likely that 
the clearly defined stages of Europe will be represented by equally well- 
marked sub-divisions in Tibet, for, as in the Triassic sequence of the 
Himalaya, hard lines of division between two consecutive stages in all 
probability do not exist and the exact beginning or end of any parti'^ 
cular stage cannot be determined. 
The oldest Cretaceous fossils found either at Kampa dzong or at 
Tuna are those occurring in the brown shales with 
mlLT^enoSar"' calcareous concretions (Kampa shales) and 
consist, as stated above, of ammonites of the 
group of Acanthoceras rhotomagense Defr. with Turrilites costatus 
Lmk. These are found in the cenomanian stage in Europe, hence the 
whole of the lower Cretaceous (neocomian to aptian) as well as the 
albian stage of the upper Cretaceous must be represented by the beds 
lying between the Spiti shales and the rhotomagense horizon. These 
include the dark limestones seen on the bank of the Giri Chu and again 
at about seven miles to E.S.E. of Kampa dzong, with the overlying 
brown shales and shaly limestone. 
The next fossiliferous horizon is that near the base of the grey 
shales, with Hemiaster Grossouvrei Gauthier, 
cenomadlm. Grypkxa s^. and /nocera?nus sp., which is also 
presumably of cenomanian age. 
From the beds between this horizon and the second scarp limestone 
no determinable fossils have been obtained, but 
Tu;onian. , . 
it is evident that the upper part of the Hemiaster 
shales, the first scarp limestone and the overlying shales must contain 
the turonian stage and possibly part of the cenomanian. 
( ) 
