GEOLOGY. 



105 



Looking eastwards from Paungdaw or the hill behind Kvauk- 



medaung, the wide depression containing the 

 Topography. , , .«,.... 



various patches of Tertianes is a striking 



scenic feature ; although in detail the Ban-Kamaiingthwe basin is 



by no means flat-bottomed, yet, seen from some height above, 



the minor elevations with which it is diversified appear insignificant 



in comparison with the high and rugged country on all sides. 



The bamboo jungle which covers it contrasts also with the 

 uninterrupted evergreen forest on the encircling mountains, but 

 this difference is due not only to different soil, bid to a considerable 

 extent to clearing and burning of the primeval forest by the local 

 Karens, whose taungya cultivation methods are more easilv pursued 

 on the low rolling country. Fires, too, when started, travel more 

 rapidly on flat land than on steep slopes. Once the big trees are. 

 destroyed bamboo at once establishes itself and holds the ground 

 against other vegetation. 



The Tertiary rocks consist mainly of conglomerate and shales, 

 with also sandstones, usually coarse, false- 

 bedded and with pebbly layers. There is a 

 transition upwards from coarse deposits at the base to fine sedi- 

 ments above, so that, owing to the synclinal arrangement of the 

 beds, conglomerates outcrop round the edges of the basins and 

 shales occupy the centres. Near Kyaukton there are also thin 

 impure limestones, and lenticular bands of lignite about 6 inches 

 thick. The pebbles in the conglomerates comprise white (vein) 

 quartz, Merged quartzite and argillite, and granite, often in a 

 ferruginous matrix. The shales are very finely laminated, and 

 when damp are soft and flexible. 



Except for fragments of silicified and carbonised wood, included 

 in shales and conglomeratic sandstones, no 

 organic remains have been seen by members 

 of the party. Fossil wood occurs mainly near Kyaukton on the 

 Ban river, an don the Ayu chaung, a tributary of the Kamaungthwe . 

 In the latter locality it is both silicified and converted into lignite, 

 the largest trunk (lignite) being about 10 feet long and 1 foot in 

 diameter. Pyrites occurs with the lignite. In the absence of 

 fossil evidence the age of the Tertiaries cannot be definitely fixed 

 but from their general facies and the presence of silicified wood 

 they may be tentatively correlated with the Irrawadi stage of Burma 

 of the Siwaliks of India. 



