42 HAYDEN: GEOLOGY OF THE PROVINCES OF TSANG AND d. 
The same beds are found again with fossils at about 5 miles to the 
E. by S. of Kampa dzong along the southern slopes of the ridge 
running from Kampa to Tatsang. The fossils are not well preserved 
being frequently replaced to a large extent by crystalline silica, 
usually in the form of bi-pyramidal crystals of colourless or of 
yellow quartz. The ammonites are consequently fragmentary, but 
sufficient material was obtainable to establish the age of the beds as 
cenomanian. 
The next overlying series is a band of pale grey shale about 250 
feet thick. The outcrops of this horizon consti- 
Hemlaster shales. 
tute one of the most conspicuous features of 
the Kampa-Tatsang range and can be seen, as a series of pale grey 
patches, from almost any point on the water-shed between Sikkim 
and the Kampa plain. Fossils are rare, but a few echinoids and 
lamellibranchs were found near the base of the shales on the flanks 
of the Kampa range, at about 7 miles E.S.E. of Kampa dzong. The 
echinoids are in a very perfect state of preservation and are closely 
allied to, if not identical with, Hemiaster grossouvrei Gauthier and 
H, cenomanensis Cotteau. The lamellibranchs occur chiefly in two 
narrow calcareous bands composed almost entirely of specimens of 
a small species of Gryphasa. The only other fossil found in any 
quantity in this bed, which may be named the " Hemiaster shales," is 
Inoceramus sp. of which several fragments were obtained in the 
neighbourhood of the Gryphsea bands. 
The same shales are seen also on the western flanks of the Kampa 
ridge between Kampa dzong and Utsi, where they contain a narrow 
calcareous band in which are numerous badly preserved specimens 
of Lithodomus sp. 
The remainder of the Cretaceous system consists chiefly of lime- 
stone which forms the greater part of the range 
Scarp limestone. 
running from Kampa dzong to Tatsang and the 
hills to the north and north-west of Tiina. The southern edge of the 
outcrop forms everywhere a well-marked scarp, in which, as a 
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