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| IIIF Color HighRes |
| Scientific Results of a Journey in Central Asia, 1899-1902 : vol.4 |
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Citation Information
TO THE LAKOR-TSO. ANCIENT BEACH-LINES. 153
his. Properly speaking, the latitudinal valley in which he travelled is the direct continuation of that in which stood our Camp CVII; but it may also be said that, in consequence of the subsidiary mountains which I have just mentioned, the valley in question bifurcates in this locality. The southern division widens out rapidly in order to make room for the Lakor-tso, as well as to effect a junction with the important valley which we had nearest to us on the south, the valley in which our Camp CVIII was situated.
To return to the shore-ramparts that still survive and the lowest part of the valley. They appear, then, to owe their existence to the fact, that they were protected between the subsidiary mountains on the northern shore of the lake and the extreme western part of the southern range, which possesses few transverse glens, while such as do exist are short and insignificant. The main stream of the latitudinal valley, which is quite distinct all the way to the gap in the biggest and highest rampart, stops there, and beyond that point no traces of erosion are discoverable. Nevertheless the breach in the rampart and the clearly defined channel of the stream down to that point prove, that the water does succeed in still getting down as far as that. After a heavy rain the stream will be pretty heavily charged with sediment, and one would expect that this sediment would deposit itself as flat alluvial sheets over the lower shore-ramparts. Yet, since this does not take place, the sediment appears to be deposited before it reaches the highest rampart, while the water runs away by a subterranean channel. But it reappears again, at any rate in part, before it reaches the existing lake, as indeed we shall soon see.
There is yet one other circumstance which must be taken into account in instituting a comparsion between that part of the bottom of the latitudinal valley which still possesses ancient strand-ramparts and the part in which they have been obliterated, and that is — time, and the changes which have meanwhile taken place in the climate. A j5yiori younger strand-ramparts and lacustrine terraces have a better prospect of being preserved than older ones; but this probability is of less importance than the circumstance, that the lake is undergoing desiccation as a consequence of the increasing aridity of the climate. Hence at the present time the sedimentation from the bordering ranges is less active, as well as less effective, than it was at the time when the lake reached an extension such as that indicated by the beach-line which I measured at an altitude of i 33 m. at Camp CIX. For this very reason too the oldest strand-ramparts, if indeed there were such, though they have now vanished, would be in a higher degree exposed to be covered up by sedimented detritus. Any way it is curious, that just the highest of the eighteen strand-ramparts, of which we crossed over eight in all, should be the biggest and best developed. But apart from the hypothesis which I have thrown out above, that the lake, when it reached up to the level of that rampart, maintained its then existing-level for a long period of time, the climate being then in a measure constant, we ought also to recollect, that this curving rampart itself stretches from the little pointed offshoot of the southern range and the nearest rocky portion of the subsidiary mountains on the northern shore of the lake, and in consequence of that
situation is indubitably better protected than the lower ramparts.
He din, Tourney in Central Asia. IV.
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