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The Desert of Kum-tagh is a section of the Gobi Desert which lies east-southeast of the Desert of Lop. It is on the other side of the Kara-koshun and reaches north-eastwards as far as the vicinity of the town of Sa-chow and the lake of Kara-nor, or Kala-chi. Its southern rim is marked by a labyrinth of hills, dotted in groups and irregular clusters,worn down as it were to mere fragments of their former skeletal structure. Between these and the Astin-tagh, intervenes a broad latitudinal valley, seamed with watercourses that come down from the foothills of the Astin-tagh. Beside these scrubby desert plants of the usual character maintain a precarious existence. Water reaching them in some instances at intervals of years only. This part of the desert has a general slope northwest towards the relative depression of the Kara-koshun. A noticeable feature of the Kum-tagh is the presence of large accumulations of drift-sand, especially along the foot of the crumbling desert ranges, where it rises into dunes sometimes as much as 250 feet in height and climbs half-way up the flanks of ranges themselves.

The prevailing winds in this region would appear to blow from the west and northwest during the summer, winter and autumn. Though in spring, when they certainly are more violent, they no doubt come from the northeast, as in the desert of Lop. The arrangement of the sand here agrees perfectly with the law laid down by Potanin, that in the basins of Central Asia the sand is heaped up in greater mass on the south, all along the bordering mountain ranges where the floor of the depressions lies at the highest level. The country to the north of the desert ranges is thus summarily described by Sven Hedin: "The first zone of drift sand is succeeded by a region that exhibits proofs of wind modelling on an extraordinarily energetic and well developed scale, the results corresponding to the jardangs and the wind-eroded gullies of the Desert of Lop. Both sets of phenomena lie parallel to one another; from this we may infer that the winds which prevail in the two deserts are the same. Next comes, sharply demarcated from the zone just described, a more or less thin kamish steppe growing on level ground; and this in turn is followed by another very narrow belt of sand, immediately south of Achik-kuduk Finally in the extreme north we have the characteristic and sharply defined belt of kamish steppe, stretching from eastnortheast to westsouthwest and bounded on north and south by high, sharp cut clay terraces.

"At the points where we measured them the northern terrace was 113 feet high and the southern 853/4 feet....Both terraces belong to the same level, and would appear to correspond to the shore lines of a big bay of the last surviving remnant of the Central Asian Mediterranean. At the point where I crossed it the depression was 6 to 7 miles, wide, and thus resembled a flat valley or immense river-bed."

• This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.