CAMBRIAN SYSTEM. 19 
about 150 feet of shale and slate resting upon the basal quartzites 
(No. i). These in turn pass down into the red, ferruginous and car- 
bonaceous series. 
Further east, again, in the lower Thanam valley, the trilobite beds 
appear to be entirely absent, and on the southern side of the Hang- 
rang Pass the silurian rocks lie upon the red and carbonaceous 
slates. Here, however, and indeed throughout Bashahr, the rocks 
are greatly disturbed, and the junctions frequently confused by 
faults : this is especially noticeable in the hills on the right side of the 
Sutlej and lower Spiti rivers, between Sungnam and Lio, where 
faults and granite intrusions are numerous, and the older palaeozoic 
beds both altered and disturbed. 
It has been seen, therefore, that the pre-silurian rocks of Spiti fall 
, into three main subdivisions — 
Subdivisions of pre- 
silurian beds of Spiti. (c) an upper, fossiliferous series of slates, 
quartzites and dolomites, only the lowest beds 
of which have been found in the areas examined by previous obser- 
vers: thickness — about 1,200 feet; 
(3) a middle subdivision, consisting of bright red and black (fer- 
ruginous and carbonaceous) slates, with some quartzites ; this is well 
developed in the Pin, Parahio and Thanam valleys, and presumably 
corresponds to Mr. Griesbach's upper haimantas : thickness — about 
1,000 feet ; 
{a) a series of dark slates and quartzites, corresponding to 
Mr. Griesbach's middle haimantas: thickness— between 2,000 and 
3,000 feet. 
The age of the highest member [c) is undoubtedly upper, and 
possibly in part middle, cambrian, and considering the relative thick- 
ness of this and the lower subdivisions, and comparing these with the 
thickness of the cambrian system in other parts of the world, it would 
seem quite justifiable to include the whole sequence, which is a per- 
fectly continuous one, in the cambrian system, and thus dispense in 
Spiti with the provisional terms " Bhabeh series," originally proposed 
by Stoliczka, and " Haimanta," subsequently adopted by Griesbach. 
C 2 ( »9 ) 
