The anomalous pattern traced on the map by the Huangho suggests that the history of the river is a complex one. In particular, the great Ordos loop seems out of keeping with any simple development of normal drainage. One theory is that the present headwaters originally followed a less circuitous route, emptying directly into the Wei Valley in Kansu instead of flowing northeast past Lanchow. Another suggests a previous outflow directly to the east from the Ordos Desert. Similarly, diversion still higher up stream has been invoked to account for the acute or reverse bends of the upper course in western Kansu. Yet again, two ideas may be combined by assuming double capture; the first, north of the gorges which separate Shensi and Shansi, and the second in central Kansu. Color is lent to these suggestions by the obviously youthful character of the gorges, by the contrasting size and . . .