PERMIAN SYSTEM. 5I 
and Diener ' as of upper carboniferous age, and should this correla- 
tion be correct, the age of the Fenestella shales should also be upper 
carboniferous. 
On the ridge behind (north-east of) Po, the beds are, as already 
stated, greatly disturbed and faulted, and the Fenestella shales 
are only separated from the calcareous sandstone (No. 4, p. 46) by a 
small thickness of shale and quartzite, the greater part of the con- 
glomerate series having been cut out. Further east, however, towards 
Thdbo, a complete, though slightly faulted, section of the overlying 
beds is seen in the hills above Lanjarse E. G. Here the Fenestella 
shales are overlain by thick beds of white and brownish quartzite 
with equally thick beds of shale. At about 300 feet above the Fenes- 
tella shales a band of shale contains fragments of brachiopods and 
bivalves, but all too badly preserved for determination. The lower 
shales are usually very fine-grained and argillaceous, but towards the 
top of the series, where quartzite bands are more numerous, they be- 
come siliceous and gritty and occasionally contain thin pebble-beds ; 
higher up the shales disappear altogether and are replaced by 
quartzites, grits and conglomerates. 
As might be expected in shallow-water deposits of this nature, the 
Permian conglo- conglomerate series varies both in character 
merate. thickness. High up on the slopes between 
Lanjarse and Po the shales contain, near their upper limit, beds of 
grit and a coarse conglomerate ; the latter rock forms a bed about 
20 ftet thick, overlain by another bed of shale, which is followed by a 
great thickness of grit, quartzite and conglomerate. 
South of Pomarang, on the right side of the Spiti river, the se- 
quence is very similar to that just described. The grits are both coarse 
and fine, and are composed of angular and rounded fragments of shale 
and limestone embedded in a coarse, slaty matrix. Similarly the con- 
glomerates are composed of boulders and pebbles of various sizes em- 
bedded in a gritty or, at times, a slaty matrix, the rock, when crushed, 
' Pal. Indica, ser. XV, vol. I. pt. 2, pp. 91, 94. 
e 2 ( 51 ) 
