212 GRIESBACH : GEOLOGY OF THE CENTRAL HIMALAYAS. 



Unconformity. 



anywhere, rather unmistakable gradations from one into the other 

 series of beds. 



The first break occurs above the upper carboniferous, upon which 



the black " Kuling " shales, with many Producti> 



rest unconformably. This is the most important 



point connected with the structure of Spiti as will be seen later on. 



Sequence of palaeozoic division. — The divisions of the palaeozoic 



rocks of the Pin valley are therefore as follows : — 



With trias-rhaetic resting conformably on : — 



9. Black Productus (Kuling) shales . 



Unconformity 

 8a. Dark flaggy limestone 



8. White quartzite series (Muth quart zite) 

 ja. Red Crinoid limestone 

 7. Earthy, dark-grey limestone 

 6. Hard, dark, concretionary 



Coral limestone with splintery shales 

 5. Dirty flesh-coioured to brown quartzites alternating 



grey and greenish shales . 

 4. CoraMimestone series 

 3. Bright red quartz-shales 

 2. Slate, quartzites and conglomerate 



series, seemingly conformable on : 

 1. Gneissose series. 



Permian. 



Carboniferous. 



> Devonian. 



with 



\ 



: j 



Silurian. 



aimantas. 



The divisions 1 to 5 correspond exactly with the silurian and pre- 

 silurian sections of the Hundes and Central Himalayan ground. Fos- 

 sils occur in nearly all the beds, but they are not very well preserved, 

 and I did not devote much time to the search for them in Spiti. The 

 rocks are so characteristic, and the lithological similarity to the east- 

 ern section is so complete, that I could pass on to the carboniferous 

 rocks without hesitation. 



The red quartz-shales (3) are as constant a termination to the 



haimantas as in Kumaun and GarhwcU, and al- 

 though the thickness is only from 200 to 300 

 feet, the bright red tint of the bed marks the boundary accurately. 



The overlying G^aZ-limestone (4) averages 300 feet in most 



sections, and consists principally of thin-bedded 

 CWfl/-limestone (4). 



r<?rtf/-limestone of dark-grey colour, with 



( 212 ) 



Red quartz shales (3). 



