ALLUVIAL FANS • 585 



from the present shore, and has an elevation of only 400 feet above 

 sea-level. It has thus an average fall oi ij/3 feet per mile, a slope 

 so gentle that it is imperceptible. Along the coast the fan extends 

 from near Pekin southward for about 400 miles to where it joins 

 the great plains of the Yang-tse-kiang, being interrupted, however, 

 by the mountainous province of Shantung. 



Owing to the very gentle slope of the fan the overflow at its 

 head and the corresponding diversion of a distributary will result 

 in the inundation of vast areas. The mouth of the river has 

 been shifted more than 200 miles north or south, such shiftings 

 having been numerous during Chinese history. "The flood of 1887 

 covered an area estimated at 50,000 square miles, immensely fertile 

 and swarming with villages. The number of people drowned was 

 at least a million and a greater loss followed from famine and 

 disease caused by the flood." (Davis-i8:_='po.) Flood plain fans 

 of this type thus furnish excellent examples of the manner of 

 destruction and burial by river silts of terrestrial organisms, and 

 they further illustrate how peat deposits in swamps may be buried 

 to be converted in the course of time iiito coals. The material 

 carried by the Yellow River is mostly fine silt derived from the 

 loess in the interior, which from its color gives the name to the 

 river. The fineness of the material accounts in part at least for 

 its very gentle slope, for it can be carried to great distances before 

 it settles out. 



Growing steadily but slowly seaward it is, of course, inevitable 

 that marginal marine deposits should be enclosed in the growing 

 fan. Very slight depression of the land would cause a partial 

 flooding by the sea, with accompanying marine deposits. In its sea- 

 ward growth the great delta has annexed the former rocky island, 

 which is now the Province of Shantung. 



The Indo-Gangetic alluvial plain is an example of a river plain 

 formed of many confluent dry deltas and carried forward by the 

 two great rivers of northern India — the Indus on the west and the 

 Ganges, with the tributary Brahmaputra, on the east. Numerous 

 small streams feed these rivers from the south slope of the Hima- 

 layas, carrying an abundance of coarse and fine debris. (Old- 

 ham-40.) The great alluvial plain extends over an area of about 

 300,000 square miles, and comprises the richest and most populous 

 portion of India. It varies in width from 90 to nearly 300 miles, 

 and entirely separates the lower peninsula of India from the Hima- 

 layas to the north. It rises 924 feet above the sea in its highest 

 portion, and the deepest boring has located these deposits at a depth 

 of nearly a thousand feet below the present sea-level. This is at 



