24 
HAYDEN: GEOLOGY OF SPITI. 
Silurian limestones. 
" arenaceous limestone, in parts largely siliceous, with beds of purer 
limestone of dark colour." The fossils that he obtained from these 
rocks were, apparently, too fragmentary and too poorly preserved to 
admit of specific determination, but from their general facies he was 
disposed to regard them as of silurian — probably 
upper Silurian — age. An examination of the 
collections made during the last few years proves that this conclusion 
was correct. The age of the uppermost member of his " Muth series " 
— the white " Muth quartzite " — is still doubtful, but the beds be- 
tween it and the red quartzite have now been found to contain fossils 
of both upper and lower silurian age. 
Near Muth, on both sides of the Pin river, good sections of this lime- 
stone series are exposed, that on the right bank being, perhaps, the 
better of the two. Near Shidn the red quartzite passes up through 
thin-bedded red and green quartzites and siliceous shales into the lime- 
stones the series falls stratigraphically, and to some extent lithologi- 
cally, into the following subdivisions : — 
White" Muth " quartzite, passing gradually down into 
8. Reddish-brown quartzite, underlain by grey sili- 
ceous limestone, weithering red and pink . . about 80 feet. 
7. Grey limestone, weathering red and brown, with 
red and brown marls . . . , • »> 70 „ 
6 Grey coral limestone . . . . . • .» 50 „ 
5. Shaly limestone, with brachiopods, gastropods, and 
corals . . . . . • . • », 30 ,) 
4. Hard, grey dolomitic and siliceous limestone, with 
grey and green shales . . . • »i 40 „ 
3. Dark grey limestone, weathering brown, with 
Cystidea above and brachiopods below . • »> 30 „ 
2. Dark, foetid limestone, with shaly lirNestone and 
shale bands : brachiopods and trilobites . . „ 200 1, 
\. Shaly and flaggy sandstones and quartzite, with 
Orthis SLwd plants, passing down through red 
and green thin-bedded quartzites and siliceous 
shales into the red quartzite . . , • „ 150 „ 
Fossiliferous hoiizons. 
( 24 ) 
Each of the subdivisions i to 8 is more or less 
fossiliferous. 
