242 MR. E. D. OLDHAM ON THE [vol. lxxix, 



moreover, the narrow part would be rapidly rilled up by river- 

 deposits, so that the estimate of the later observer is in substantial 

 agreement with the survey of the earlier, and the permanent 

 length of tbe lake may be placed at about 15 miles. 



The landslip itself was of the ordinary type of mountain-slip ; 

 it was a downward rush of a mass of debris, moving more as a 

 fluid mass than as either a slide, or a fall, of separate fragments, 

 carrying on its surface, and embedded in it, huge unbroken masses 

 of rock measuring hundreds of cubic feet in bulk. Where this 

 moving mass impinged on the opposite side of the valley its 

 momentum was cheeked, the upper surface surged up and, not 

 having sufficient fluidity to return, was left banked against the 

 hillside, forming a barrier across two minor tributaries from the 

 south, in one of which a small lakelet was formed. This much is 

 evident from Col. Spilko's survey and description, from which 

 it is also evident that the great slip at Usoi was by no means the 

 only one formed at the time of the earthquake. Upstream, his 

 survey shows several smaller landslips in the direction of Sarez, 

 probably those that blocked Capt. Zaimkin's progress in April 

 1911 ; and, even from the accounts collected by Col. Spilko, it is 

 sufficiently evident that there must have been numerous others 

 farther down the valley, in the districts which were not visited by 

 him. The information, however, would have been very scanty but 

 for the fact that, about two years later, Sir Aurel Stein travelled 

 down the Tanimas valley to its junction with the Murghab, and then 

 up that valley past the great slip and the lake of Sarez, and his 

 graphic description l of the condition of the country, four years 

 after the earthquake and landslip, throws much light on what 

 would otherwise have been obscure and doubtful. 



He states that already in the Tanimas valley he had come upon 

 huge masses of debris, which had fallen from the slopes of the 

 flanking spurs, and spread for several miles across the open valley- 

 bottom. On turning up the Murghab valley, progress in its narrow 

 gorge proved very trying, owing to the results of the earthquake, 

 which had transformed the surface of the mountain-region in a 

 striking fashion. In these defiles huge landslides had choked up, 

 in many places, the whole river-passage, and destroyed the tracks. 

 The big river, once rivalling in volume the Ab-i-Panja, had 

 altogether ceased to flow, and strings of alpine tarns had replaced 

 it. It took three days' hard travelling, along the steep spurs and 

 over vast slopes of debris, to get to the point, near the mouth of 

 the Shedau lateral valley, Avhere the fall of a whole mountain had 

 completely blocked the river, and converted the Sarez Pamir into 

 a lake more than 1-5 miles long, still spreading up the valley. 

 Enormous masses of rock had been pushed, b}' the impetus of 

 the landslip, up the steep spurs flanking the Shedau valley, 



1 ' A Third Journey of Exploration in Central Asia, 1913-16 ' Geogr. Journ. 

 vol. xlviii, 1916. The passages referred to in the text above are on pp. 214 

 et seqq. 



