GEOLOGICAL CONDITIONS LN EELATION TO EARTHQUAKE. 1q7 



difficult to find even small pieces which have not been broken in 

 all directions, and which are not traversed by veins and fissures 

 filled with secondary calcitc or dolomite. This pulverization and 

 brecciation is put down to the effects of the enormous stresses 

 set up by the great earth movements, which took place at the 

 close of the Mesozoic period, and to the removal in solution 

 by carbonated waters of immense quantities of the rock. Large 

 as the quantities of limestone removed in this manner must be, 

 and far-reaching in effect as this agency doubtless has been, 

 I regard it as a secondary process, which has accentuated the 

 universal brecciation to which the formation has a whole has been 

 subjected by tectonic stresses. 



Faulting of the Northern Shan States. 



The account which follows here is based entirely on the work 

 of La Touche( 1 ) (see PL G). 



The western edge of the Shun plateau is a fault scrap, 

 bounded by a great fault which breaks into 

 Outer Boundary ty . Q } )ranc } ieSj onc following the edge of the 

 alluvium east of the Irrawaddy. and the other 

 crossing the river below Mandalay and dividing the Sagaing hills 

 from the plains of Sagaing and Shwebo. The period at which 

 the folding and faulting of these rocks took place is uncer- 

 tain. Suess has remarked that the Burmese arc of folding pre- 

 ceded that of the Himalaya. La Touche is of the opinion that 

 it was anterior to that of the Himalaya for a time, though 

 for the most part the great thrust movements, the one acting 

 from the north and the other from the east, must have proceeded 

 simultaneously. He has also drawn attention to the analogy 

 between the results of the movements which produced the 

 Burmese and Himalayan arcs respectively. The Shan plateau 

 is held to correspond with the Tibetan plateau, both of them being 

 elevated floors of ancient oceans now undergoing abrasion and 

 reduction to peneplains. The outer edge of each is bounded by 

 what is virtually a scarp, and in both cases there exists a zone 

 of Arelnean and Palaeozoic rocks, composed generally speaking of 

 strata of greater age than those of the plateau beyond. In each 

 case the zone is bounded by a great fault forming the inner edge 



i 'I' I) La Touch-: Oeology of tin- Northern Shun .States. Mrm.. Geol. Surv., 

 Ind., Vol. XXX 1 \ 



