国立情報学研究所 - ディジタル・シルクロード・プロジェクト
『東洋文庫所蔵』貴重書デジタルアーカイブ

RICHARD STRACHEY'S DESCRIPTION OF THE EFFLUENT STREAM.   89

rovar, he found on his way back that its watershed was almost close to the edge of Rakas-tai and hardly so much as 10o feet above the level of the lakes.

Along the S.E. shore of Rakas-tai he found a great raised beach, at some 200

or 30o yards from the edge of the water and consisting of granitoid detritus. The old beach-lines, which I measured in 1907 he calls a series of steps or parallel roads, situated between the high-water level of the lake and the uppermost of the beaches, which Strachey found to rise above all in >- a great mound of very remarkable height». He could not help noticing these most strikingly developed features, a consequence, as he believes, of the violent S.W. winds which blow so regularly in the afternoon, and constitute thus a permanently dead lee shore.

As to the fluctuations in the level of Rakas-tai, he comes to the following very

clever conclusion worthy of a well-trained observer: »There is no evidence available to show whether there is any considerable variation in the level of these lakes from year to year, or from one season to another; but I think that such variations as must have taken place to explain the existence of some of these beaches are hardly compatible with existing conditions, and it is probable that these lakes have been gradually drying up, as seems to be the case in most of the lakes that have been observed in other parts of Western Tibet.» In the chapters of this work dealing with my own journey I shall have to return to this question.

He concluded that the Karnali had cut out its deep channel in deposits, con-

tinuous with those of the great plateau and caused by the same agencies. From his own and his brother's observations he found it certain that Gurla and most of the highest mountains were chiefly made up of gneiss or mica schist with a comparatively small quantity of granite.

Henry Strachey had discovered the source of the Farina Yankti in 1846.

Both at this river and at Gunda Yankti, Richard Strachey came across unmistakable moraines of old glaciers. The interval between two old moraines was precisely on the same level as the great plain, or was actually a part of it, and it hence became evident that the mounds over which he had passed must have been formed along the rivers, and the agency of glaciers readily suggested itself. He thinks the lake basins may in the same way have been cut out by glaciers.

The map accompanying this paper is interesting and gives a good idea of the splendid and, from all points of view, important work of the brothers Strachey (Pl. XII). It gives the routes of Moorcroft, 1812, Henry Strachey 1846, Richard Strachey 1848, and the route of H. and R. Strachey, 1849. As regards the eastern shore of the Manasarovar the map is and must be insufficient. Three rivulets enter the

weisbar, dass es sich nur um einen zeitweise funktionierenden Abfluss oder gar vielleicht um einen frillier vorhandenen, aber heute versiegten Abfluss handelt.» In the first suggestion about a temporary efflux he has found the right solution. The second alternative does not very well agree with R. Strachey's words in the quoted article (Geog. Journ. Vol XV, p. 395): »From the height to which we climbed we looked down on the stream that connects Manasarowar and Rakas-tai.»

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