34 COGGIN BROWM : THE BURMA EARTHQUAKES OF MAY L912. 



Mayiuyo the line crosses the limestone plateau to Wet win where 

 it descends a steep scarp facing the valley of the Ke-laung stream. 

 From the crest of this ridge the view to the B. is dosed by an 

 even-topped scrap which follows the line of the great Kyaukkyan 

 fault, and as the line proceeds on across the plateau through Hsum- 

 hsai, the latter becomes more and more well defined. To the S. a 

 long line of precipitous limestones cliffs marks the position of the 

 crest, but at the gap where the railway and the cartroad cross, 

 these are not conspicuous. Mr. La Touche was the first to point out 

 how the rise at this point takes the form of a uniclinal flexure in 

 the limestones rather than a fault scarp, and the ascent from the 

 valley is only 400 feet, but there is a distinct fault along the crest 

 with a down-throw to the W. Further to the S. the throw 

 increases until the relative difference in level becomes about 3,000 

 feet. Between miles 450 and 451 (Hsum-hsai is situated' at 

 mile 413;, and Nawnghkio at mile 466), the built up earth banks had 

 cracked and slipped down towards the W. The Agent of the Burma 

 Railways reported that 300 tons of earth slipped down and blocked the 

 line at this point. A little further on, the pass cutting is situated. 

 At this point the limestone is intensely crushed and traversed by 

 shekensided planes in greal numbers, owing to the proximity of the 

 fault which appears at the crest. The sides of the cutting through 

 this crushed limestone are between 30 and 40 feet high and a 

 great deal of rock had fallen, mainly from the slickensided planes. 

 A few yards from the cutting on the N., the line which used to run 

 perfectly straight, was bent into a smooth curve which continued 

 without any dislocation for some 80 or 90 yards. This had occurred 

 close to the actual line of the fault, and if the thrust which caused 

 the curve acted in a direction normal to it, it must have taken place 

 from N. 15°— 20 \\ r . According to the report submitted by the 

 Agent of the Railway, the bank m the neighbourhood of mile 451 had 

 also flipped away towards the [y and sunk 5 feet for a distance 

 of 150 yards. Small landslips are also reported to have taken place 

 between miles 447-8 and 445-6. By these occurrences the line was 

 blocked, but it was reopened for through traffic on May 25th 

 Bridge 190 between Hsum-hsai and Nawnghkio, built of massive 

 stone-work, was badly cracked in both wing walls. I also noticed 

 frequent small cracks in the " terra rossa " of the plateau bor- 

 dering the line. The pagoda on the hill near the station at 

 Hsum-hsai was broken down. 



