50 



tlAYDEN : GEOLOGY OF NORTHERN AFGHANISTAN. 



is often bright red, and pebbly sandstone, underlain by shale and 



sandstone. At Faranjal the Gborband limestone is faulted and brec- 



ciated, and at about half a mile higher up the valley, there is a large 



mass of intrusive serpentine. Thence to the head of the valley, the 



limestone continues along the left side, whilst, on the right, it is to a 



great extent covered by Tertiary deposits. Immense masses of tbese 



fill the valley of the Turkoman dara in the neighbourhood of Lolinj, 



and extend over the hills on the east, lying unconformable on the slate 



and limestone series. They consist of clay, shale and conglomerate, 



and must be at least 2,000 feet thick ; they have been considerably 



disturbed, and sometimes dip at angles of 30° and over, though the 



general effect is more or less flat. 



At the head of the Ghorband valley, limestone extends over the 



southern slopes of the Hindu Kush and probably 

 The Shibar Pass. , * „ , . 1 J 



over part of the downs of the Shibar pass. In 



crossing the pass, I did not follow the road, but went up the Sangandao 



valley, for a few miles, then crossed the hills westwards and joined the 



road again near the western foot of the pass. Looking southward from 



the hills above the pass one sees a broad wind-gap filled apparently with 



soft Tertiary clays and conglomerates similar to those of Lolinj in the 



Turkoman dara. Behind these, again, is a high range of dark rocks, 



the continuation of the Koh-i-Baba where it merges into the hills of 



Ghorband and the southern flanks of the Hindu Kush. The rocks 



also are probably the continuation of those of the Koh-i-Baba, that is to 



say of the Kalu series, with the hematite bed on the crest of the range. 



On the north of the Shibar pass, I noticed only limestone ; the same 



rock runs westwards into the Shumbal valley, and the road to Shumbal 



caravansarai and thence to Balula passes through a magnificent gorge 



carved out of the steeply dipping — often vertical — beds of limestone 



(Plate 9) . In the upper part of the gorge, just above the junction of 



the stream from the pass with the Shumbal river, the limestone cliffs are 



honeycombed with pot-holes, which are full of river pebbles but are many 



feet above the present stream level. Both in the stream-bed and on 



