108 CchicIN BROWN: TIIK BURMA EARTHQUAKES OF MAY L9iS. 



of the " f ore-deep " that separates them from the foreland of the 



continent beyond. In front of these again there occurs a zone 



of faulted and folded Tertiary strata, in the one case represented 



by the Tertiary series of the Irrawaddy valley, and in the other 



by the Siwalik and associated strata of the Sub-Himalayan zone. 



The results of the compressive Tertiary forces which have effected 



Results of the the Shan plateau can be divided into two 

 compressive Tort lary 

 movements. groups :— 



(1) Regular folds, accompanied by overthrusts and reversed 



faults parallel to their strike. 



(2) Vertical faults, due to the sagging down of the underlying 

 Archaean floor. These bear no relation to the strike of the rocks, 

 follow more or less straight lines for long distances, are often at, 

 right angles to each other, and sometimes still form conspicuous 

 surface features in the form of precipitous scarps of limestone 

 extending directly for many miles. There is evidence which tends 

 to prove that the first type of dislocation preceded the second. 



The following are the members of the series of parallel faults 

 which have been recognised up to the present 

 time. Their locations can be perceived from 

 PI. No G. 



1. The outer bounding fault which has brought up the Arcluean 

 rocks opposite Mandalav. 



2. The Tonbo fault, probably a branch of the former which 

 cuts off the Plateau Limestone at the foot-hills to the east of Manda- 

 lay, and brings it up against the Arcluean. 



3. The Sedaw fault, which runs due north and south, and 

 brings the Ordovician beds into contact with the Plateau Limestone. 

 It extends north into the Kyetmaok valley and south into the 

 Myitnge gorge. 



4. The Zebingyi fault, running into the gorge of the Myitnge, 

 and bringing the Nyaungbaw (Silurian) beds against the Plateau 

 Limestone. 



5. The Chaung Magyi fault, probably continuous up the valley 

 of the same name, and bringing the Chaung Magyi strata into 

 contact with the Mogok gneiss. 



(*). The Pyintha flexure, marked by a, folded zone of N vawnvbaw 

 limestones. which form the final step up to the main plateau east 

 of Zebingyi. and which is almost certainly faulted along the 

 crest of the ascent. 



