191^.] STEVENSON— THE FORMATION OF COAL BEDS. 535 



to 500 miles. The greater part of this plain descends very gently 

 toward the sea and, being generally below the level of the Hoang-ho, 

 it is exposed to disastrous inundations attending the rise of that 

 river. The flood of 191 1 is said to have covered an area 45 miles 

 wide and several hundreds of miles long. The plain is the work of 

 the Hoang-ho conjointly with the Yang-tse-kiang. It is a vast 

 swampy area, in great part devoted to rice culture. Pumpelly^^° has 

 shown that the Hoang-ho has shifted its course many times during 

 the historical period. A Chinese work, published in 1705, states 

 that the course of the river was regulated by Yu, which makes prob- 

 able that diking had been undertaken and the plain placed under 

 cultivation fully 2,000 years before the Christian era began. Pum- 

 pelly republished nine charts, showing changes in the channel-way 

 during 3,000 years. The stream is mighty, turbulent, subject to 

 enormous annual increase of volume, due to rainfall on the distant 

 Kuen-Luen mountains, and it has always been a source of terror to 

 the millions inhabiting the plains. Dikes have caused elevation of 

 the stream bed, which, prior to the last great change, was apparently 

 higher than the adjacent areas from Whang-ho to the mouth, a 

 distance of 400 miles. Before that change, which took place about 

 1850, the river flowed westwardly to the Yellow Sea, entering it 

 south from the Shan-tung peninsula, about 50 miles in the same 

 direction from Pei-chow or about 150 miles north from the Yang- 

 tse-kiang. The breach occurred near Fungpeh in Suchan and the 

 water flowed away to the Gulf of Pechele on the north side of the 

 Shang-tung area. The passage was by way of the Tat-sing river, 

 whose waters were increased to six times their former volume. The 

 new mouth is more than 350 miles west of north from the old one. 

 By 1858, the old mouth was dry ; but in 1863, the river had not yet 

 determined its new channel and water still spread over great tracts 

 north from Tsinan, the capital of Shan-tung. 



Blanford^^^ states that the Ganges-Indus-Brahmapootra plain of 

 northern India embraces about 300,000 square miles and is from 90 



''" R. Pumpelly, " Geological Researches in China, Mongolia and Japan," 

 Smithson. Contr., Vol. XV., No. 202, 1866, pp. 46 et seq. 



'" W. T. Blanford, " A Manual of the Geology of India." Calcutta, 1879, 

 pp. 391, 394, LX. 



PROC. AMER. PHIL. SOC, LI. 207 H, PRINTED DEC. l6, I9I2. 



