166 ANNALS NEW YORK ACADEMY OF SCIENCES 



from the Himalayas 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. . ... It 

 abounds in gravels and conglomerates near the sloping borders, but luta- 

 ceous or clayey deposits, more or less arenaceous, prevail over much of 

 the plain, especially near the center, with only subordinate deposits of 

 sand, gravel, and conglomerates. Beds of blown sand of great thickness 

 are found in some regions. . . . Shells of river and marsh molluscs 

 are occasionally foimd, and calcareous concretions and nodules of irreg- 

 ular shape, locally known as JcanTcar, are frequent. . . . Calcareous 

 tufas also form conglomerates in the stream beds by cementing pebbles 

 derived from the hills. In the clays along the borders and in the shoals 

 of the Jumna Eiver a great variety of vertebrate remains has been found, 

 including elephant, hippopotamus, ox, horse, antelope, crocodile and 

 various fish.'^ Grabau gives further descriptions of these deposits, much 

 of which would apply to the Morrison. 



Lakes are not especially abundant on these plains, though some are 

 present. The large rivers are braided in a complicated manner. An in- 

 teresting feature is shown in the delta portion of the Ganges, where a 

 large tributary, the Brahmaputra, joins the main river helotu the point 

 where one of its largest delta distributaries, the Hooghly, is given off. 

 These features are shown on any large map of India. 



Grabau also gives a description of the Nile flood-plain. Extracts from 

 this description are here quoted. 



"A striking example of a flood-plain is afforded by that of the Nile, 

 which flows from a well-watered region through a desert country without 

 receiving a tributary for a thousand miles, except a few small wet weather 

 streams. Entrenched beneath the desert uplands this flood plain holds 

 its own for a length of 500 miles, and maintains a width of from 5 to 15 

 miles, broadening on the delta to over 100 miles. The annual inunda- 

 tion of the flood plain is caused by the northward movement of the belt 

 of equatorial rains in summer. The flood begins in June and usually 

 rises 25 feet or more at Cairo in the late summer or early autumn. The 

 annual addition of the river silt causes a slow rising of the entire flood 

 plain estimated to amount to 4% inches a centur}'. 



"This region furnishes an instructive example of widely varying con- 

 temporaneous deposits within the same general area. On the one hand 

 occur the drifting, cross-bedded, well rounded and pure quartz sands of 

 the desert, and, on the other, the extremely fine, well-stratified muds of 

 the river flood plain." 



