| CHAPTER LX. LATITUDINAL DEPRESSIONS OF NORTHERN AND CENTRAL TIBET. We have now examined and compared the three southern latitudinal valleys of Tibet so far as their absolute altitudes, their lakes and rivers, and their probable historical development are concerned. If the white patches of terra incognita of the interior of the Tibetan plateau-land were not still as extensive and numerous as they are, and if our geographical knowledge were not so limited, the best plan would, of course, be to continue our examination step by step to the north, starting from the deep and well-marked latitudinal valley of the Selling-tso—Panggong-tso. But at our first attempt to find out the situation and the stretching of the next great valley we would feel our steps lost on too unreliable ground. Leaving alone the western parts which so carefully have been explored by DEASY, RAWLING and others, we find innermost Tibet crossed by only the following travellers' routes (taking them from west to east : HEDIN, BOWER, HEIDIN, DE RHINS, LITTLEDALE, HEDIN, HEDIN, BONVALOT, HEDIN, ROCKHILL, and, in the far east outside of the plateau-land, A—K— and PRSHEVALSKIY; the latter on several lines. The journeys still farther east in the Tibetan-Chinese borderland, such as POTANIN's, KOSLOFF's and many others, do not belong to the little-known regions of our examination. The routes of all the travellers just mentioned are chiefly meridional and run from north to south, all being attempts to penetrate into the nearly hermetically closed provinces of Southern Tibet. In consequence of this distribution of the routes, it proves to be extremely difficult to bring the different travellers' discoveries of ranges and lake depressions into harmony and correspondence with one another. On the other hand, this difficulty completely disappears if we turn our attention to travellers whose itineraries proceed parallel with the latitudes. In a land of folds, as Tibet, where the folds with few exceptions stretch from west to east, it is naturally enough much easier to travel in the latitudinal valleys between them than to travel along the meridians crossing innumerable ranges and crests. In the | |
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