Note 4 — APPENDICES

Loess was formerly regarded as simply a deposit of glacial or fluvial origin, but Richthofen's theory that its subsequent distribution was largely due to wind-transport (cf. "China," Bd. I., pp. 56 ff.) is now generally accepted. The fact that it is found heaped up against the sides of mountains and contains land, and not water, shells, is unanswerable evidence. For its general character and distribution, see Sir Archibald Geikie's "Text-book of Geology," 4th ed., I., pp. 439 f.; II., p. 1351. It may be noted that the formation of loess-beds and sand-deserts is a continuous process at the present day, under the strong winds which prevail in certain seasons in Central Asia; and even when there is little wind the air is often thick with fine dust. The reverse of the process is visible in the effects of wind-erosion, very striking instances of which have been described by Dr. Stein; cp. e.g. "Ruins of Khotan," p. 189 f., and "Ancient Khotan." I., p. 107.