Page:Mongolia, the Tangut country, and the solitudes of northern Tibet vol 2 (1876).djvu/286

260 former (at all events in the western side which we explored), the range may be divided into three belts, viz. the marginal, the tree-belt, and that of the alpine meadow-land.

The first of these, with the strip of undulating plain belonging to it, has an argillaceous soil studded on the plain with boulders, and on the hills with blocks of fallen rock. In this section the cliffs are smaller and fewer in number than in the other two. This marginal zone or skirt of the mountains is nowhere over a mile and a half in width.

Here the only trees are occasional stunted elms; amongst the bushes we observed the yellow briar (Rosa pimpinellifolia), the caragana, and an occasional Ephedra, such as we had seen in Tsaidam, at the foot of the northern slope of the Burkhan Buddha; nearer the mountains the commonest kinds are the thorny convolvulus (Convolvulus tragacanthoides), and prickly astragalus (Oxytropis aciphylla). The chief herbaceous plants are the thyme (Thymus serpyllum), Solomon's seal (Polygonatum officinale), Pegonum nigellastrum (the last named belonged exclusively to the plain), the onion, also growing on the mountains as high as the alpine region, the