14 



IIAYDEN : GEOLOGY OF NORTHERN AFGHANISTAN. 



one over the Lataband and a southerly route over the Haft Kotal to 



Klmrd Kabul. I have travelled only by the lirst route, but returned 



from Kabul along the third to Tangi Tarakki, a few miles east of 



Khurd Kabul, whilst Mr. Griesbach has already described the rocks 



ween along the road over the Lataband. 



After leaving Sarobi, the road via Tangi Gharu rises over a 



flat-topped ridge of Siwalik beds which separates 

 Tangi Qbaru. . 



Sarobi from the Kabul river at Kach-i-Sher Khan. 



On the top of the ridge, inliers of grey limestone, weathering brown, 

 crop out through the Siwaliks. The limestone exactly resembles the 

 Megalodon limestone in the Para stage of Spiti, and is full of similar 

 heart-shaped sections of lamellibranchs, some of which are as much as 

 a foot in length, and probably represent Dicerocardium, whilst the 

 smaller ones are Megalodon. The same limestone appears to continue 

 to the west along the high ridge on the right side of the Kabul river. 

 The road strikes the river-bank at the small village of Kach-i-Sher 

 Khan, and just above this point the Siwalik beds end and give place to 

 serpentine which extends for about two miles up the river. On the hill- 

 sides above the right bank, light-grey limestone, much crushed and 

 folded, is associated with the serpentine. Westwards these are capped 

 on the hill-tops by cliffs, which must be 1,000 feet high, of Siwalik 

 conglomerate ; this gradually spreads down into the valley of the river, 

 which widens out, and, at Gogomanda, is a wide basin full of Siwalik 

 deposits. Just above Gogomanda, these disappear again, and the river 

 rushes through a narrow gorge cut through steeply dipping beds of 

 limestone and slate with great masses of intrusive serpentine. Similar 

 rocks continue all the way to Ishpul Baba. Above this, slate and schist, 

 with serpentine and other igneous rocks, extend for some distance up 

 the gorge, when they give place to gneiss and granite. Towards the 

 head of the gorge, the gneiss and granite form the lower slopes, the 

 hills being capped, about 2,000 feet above the river, by thick beds 

 of limestone belonging to the Khingil series. Here and there beds of 

 this rock have been brought down by faults and run in almost vertical 

 bands across the river, but as a rule it is confined to the hdl-tops. 



