Some tentative conclusions may be drawn with regard to the development of the Yangtze estuary, based on a priliminary analysis of sea charts and hydrological data, as well as on field researches in recent years. 1. On the broad continental shelf of the East China Sea, which is about 90-140m below sea-level at the outer edge, lies 2 ancient submarine deltas one above the other off the Yangtze mouth. They are not coinciding in areal position and a southward displacement seemed to have occurred during the growth of the younger one. Submarine sand-banks may be depicted, at intervals, 50 m deep and 200km off the coast.