1867.] the Western Himalaya and Afghan Mountains. 31 



Section of the Northern extremity of Mount Sirbun, near Abbotlabad, 

 from E. to W. bearing S. {not drawn to scale.~) 



1. Very compact and very hard Co-mean rock, composed of a paste of white m 

 feldspar and grey hornstone in intimate combination. The joints and exposed 

 surfaces are smooth and have a quartzy glimmering. In the paste there is 

 often a partial separation of white feldspar in spots of a dull white colour. 

 Splinters of the white spots can be rounded on their edges before the blow- 

 pipe, but the grey paste of the rock appears to be more refractory, though 

 there is certainly a softening of the mineral compound and a slight smoothing 

 of sharp edges after long exposure to heat. It is a bed of very considerable 

 thickness, stratified and much jointed. 



2. White quartzite in a brecciated state, the pieces being recemented 

 together by a grey feldspathose paste. It appears as if the bed had been 

 broken after its formation and the fragments reunited by a feldspathose paste. 



3. Very heavy, chocolate-coloured, clay-stone, with bands of quartzite. 



4. Indurated clay, with round nodules, the size of a bean, of a black 

 mineral having the lustre of jet, whitening to a milk-white colour before the 

 blow-pipe, and finally melting with difficulty on thin edges ; it belongs probably 

 to the hypersthene group. The clay itself is grey, smooth and meagre. 



5. Chloritic clay ; grey, very smooth and soft to the touch ; hardness of 

 slate. It is full of ninute round grains of a semi-transparent mineral, grey 

 like the clay, but a little darker. The clay becomes white and meagre before 

 the blow-pipe ; it is unaffected by muriatic acid, and does not form a pasty 

 mass with water, either before or after grilling. 



6. Limestone, at first extremely arenaceous and argillaceous, and presenting 

 particles of dirty blue and brown colour. It becomes gradually conglomeratic 

 and at the same time thin-bedded, the layers being made of layers of pebbles 

 of limestone cemented by a calcareous sandy cement ; the top of the layer 

 appears to have been worn flat by the action of the waves, before the deposit 

 of the next stratum took place, the pebbles appearing as sections on the surface 

 of the bed. The next layer is a muddy limestone containing a few fiat athyris, 

 remarkable especially for three internal raised lines or ribs proceeding from the 

 beak as far as the middle of the valve. But these shells are in a very bad 

 state of preservation. This layer is only two feet thick, and is succeeded by 

 another equally thin and containing numerous debris of gasteropods and 

 corals. Then comes a black, sometimes blue-black limestone, extremely foetid. 

 The bluer portions are crossed by white lines intersecting each other in all 

 directions and containing only debris of fossils. 



The limestone forms altogether a bed of about thirty feet, when it is cut by 

 a fault which causes it to be repeated, and a succession of faults directed 

 W. N. W. to E. S. B. keeps the same limestone on the surface for more than 

 half a mile, it becomes finally covered by nummulitic limestone. 



