THE JURASSIC SYSTEM. 
27 
As observed in this locality, then, the sequence is — in descending 
order — 
4. Crinoid limestone. 
"XuraSS^ 3- Slate and quartzite. 
' I. Brachiopod limestone and upper beds of Dothak 
series. 
Nos. I and 2 are probably Jurassic (lias), while No. 3 is almost 
certainly so. 
Between this valley and the Tremo La, numerous similar valleys 
open into the Phari plain ; the low hills on either side of these 
appear to be invariably composed of slate or shale, which dips towards 
the plain, the strike thus bending round from approximately 
E.NE.-W.SW. on the south to nearly N.-S. on the eastern side 
of the plain. Unfortunately none of these intermediate valleys could 
be visited, but the sequence of beds in them is probably similar to that 
just described. 
The hillmass which stands out prominently in the middle of the 
plain is composed of slate and quartzite and 
Central hills of Pharl ■ l a 11 -j r ^.l j- 
pj^j^ IS cut on on all sides from the surrounding 
rocks. Its western boundary is the important 
Dothak-Tang La fault already mentioned {supra p, 20). On all 
other sides a belt of recent deposits separates it from the neighbouring 
spurs, but its component rocks can be unhesitatingly referred on 
lithological grounds to the Jurassic system. 
To the north-west of this hill, on the right bank of the river 
limestones again appear, dipping: to the north- 
Upper limestones. 110 
west. They are separated from the Khongbu 
series by the Dothak-Tang La fault but their relation to the beds 
of the central hill is not apparent from their position and dip 
they are probably younger, but the junction, which is obscured by the 
recent deposits of the river valley may be a faulted one ; they have, 
however, been referred provisionally to the Jurassic system. Like 
all the other sedimentary rocks of this neighbourhood they are 
crushed and disturbed, no doubt owing to the proximity of the 
( 148 ) 
