1918.] The Geotectonics of the Tertiary Irrawaddy Basin. 419 
The most remarkable thing about these old raised river 
gravels is that they tell us that river gradients were univer- 
sally steeper and river currents more rapid in pleistocene times 
in the present day. Now-a-days the Irrawaddy at Ye- 
nangyaung merely transports coarse. sand; formerly it was 
able to carry pebbles the size of an egg. Now-a-days the 
Yaw River carries small gravel to the ford at Thanbaya-aing ; 
formerly it carried very substantial boulders of nearly one 
cubic foot to that point. 
n several spots in the Saw township of the Pakokku dis- 
trict (near Anain in the Pindaung chaung, near Hnetchaung 
in the Kyauksit chaung, near Saw in the Saw chaung), enormous 
boulders of rock 6 to 8 ft. in height are seen lving in the bed 
of the stream, or on the banks hard by. In the first locality, 
these boulders were composed of Paunggyi conglomerate, _ 
the bed of the stream or on its banks, but they are occa- 
The Age of the Anticlines of the Irrawaddy Basin.—Having 
explained the Irrawaddy Basin as a su iding geosyncline, 
ve may consider now the age of the small anticlinal folds in this 
in. 
bas 
8. 
First there is the Pondaung Range which is over 
niles long, and rises to a height of over 4,000 ft. : In the pet 
valley near Tilin there are deposits of gently dipping Se adi : 
“ary gravels (Maw gravels), a local facies of the Irrawaddies, 
