4o HAYDEN : GEOLOGY OF THE PROVINCES OF TSANG AND 0. 
Thence on to Nangkartse, throughout the hills surrounding 
Yamdrok Tso, and again along the valleys of the Brahmaputra and the 
Kyi Chu, metamorphism is practically universal, due first to the many 
diabase intrusions around the shores of the lake and subsequently 
further north, to granite. 
In the immediate neighbourhood of Lhasa granite is the prevailing 
rock and the local sedimentary beds are highly metamorphosed 
but Jurassic rocks still predominate in the surrounding hills and 
appear to continue far to the north towards Nam Tso. From the 
summit of the Pempogo La can be seen an endless succession of 
shale and quartzite, striking E.-W. and extending across the Pempo 
valley into the ranges to the south of Nam Tso. The apparent 
regularity of the bedding points to comparative absence of disturbance 
among the rocks of these ranges and since Cretaceous fossils 
[Oniphalia trotteri Fstm.) were found by Pandit Nain Singh in the 
neighbourhood of the lake,' it is probable that an expedition across this 
belt of country would be productive of valuable stratigraphical results, 
CHAPTER VL 
THE KAMPA SYSTEM (CRETACEOUS AND TERTIARY). 
A more striking contrast than that between the Jurassic and 
overlying systems of southern Tibet it is difficult to conceive. The 
former is of enormous extent, is composed chiefly of arenaceous and 
argillaceous beds and is, with one rare exception, sparsely fossiliferous, 
while the latter is of very small extent, consists chiefly of calcareous 
rocks and contains a large and varied, if not well-preserved, fauna. 
These younger beds are especially well exposed in the neighbour- 
hood of Kampa dzong, where they form the conspicuous range of 
hills standing out in the middle of the plain fsee p. 31) ; they may 
therefore be appropriately named the Kampa system. Although the 
' Rec. Geol. Siirv. Ind., X, p. 21. 
( 161 ) 
