SILURIAN SYSTEM. 29 
examination of a wider area has proved that the sequence, as seen 
at these two villages, is very incomplete, for in other localities the 
carboniferous rocks include several bands of quartzite, all exactly 
similar to one another and to the Muth quartzite, while one of the 
highest of these occurs immediately below limestones containing a rich 
carboniferous fauna.^ 
In Kumaon and Garhwdl a white quartzite has been described by 
Eastern representa- Mr. Griesbach as overlying his "red crinoid 
lives of Muth quartzite. limestone," and has been identified by him with 
the Muth quartzite, — an identification which is almost certainly correct. 
Since he believed the " red crinoid limestone " to be lower carboniferous, 
he naturally referred the white quartzite to the upper part of the 
same system. It has, however, now been ascertained that the Spiti 
representative of the " red crinoid limestone " is certainly not younger 
than upper silurian, and in view of the gradual passage between it 
and the Muth qijartzite, and the complete absence of unconformity, 
it is safe to assert that the latter formation is not younger than 
devonian. 
The silurian system, as described above, extends with little 
Extent of silurian variation throughout the whole of Spiti. To the 
system. south-east it passes over the dividing range into 
the valleys of the Thanam and Teti rivers in Bashahr (PI. X), and can 
be traced along the hills on the left side of the Thanam valley to the 
Hangrang Pass. In this area it is of smaller extent than in Spiti, having 
been greatly eroded in permian times (PI. XI) ; in places the whole 
of the Muth quartzite and silurian limestone have been removed 
and the permian beds are found resting on the red, lower silurian 
quartzite. Similar erosion of the Muth quartzite was noticed by Mr. 
Griesbach in Niti.* 
To the north-west the silurian beds are found at Tr^kse, near 
Losar in upper Spiti, on the road to the Kunzam Li, where they are 
* It is not, however, intended to imply that this quartzite is necessarily the 
equivalent of the Kashmir band. 
' Memoirs, G. S. 1., yol. XXllI, p. 62. 
( 29 ) 
