32 GRIMES : MYINGYAN, MAGWE AND PAKOKKU DISTRICTS, 



that they are rapidly becoming lower still and tending to die down 



entirely. 



The Singu hills and the southern part of the Tangyi hills have 



been demarcated into blocks of one square 



Maps available- ., , ,,,,,, t i 



mile each, and these blocks have been mapped 



on the scale 8*= i mile. The Singu hills have been marked out as 



blocks of the Yenangyaung oil-field, and here the miocene beds are 



exposed in blocks 50 N to 59 N ; they are not, however, as we have 



seen before, on a continuation of the Yenangyaung anticline, and they 



are really not part of the Yenangyaung oil-field at all, but might 



more properly be called the Singu oil-field. This line of demarcated 



blocks, too, does not run parallel with the axis of the anticline, but 



in a somewhat inclined direction, so that it is only in the northernmost 



blocks that the crest of *the anticlinal arch comes into the mapped 



area at all, being first seen in the south-east corner of block 58N. 



South of this it is to the east of the maps. The Tangyi hills, from 



their southern end on the Irrawaddi, are demarcated into blocks of 



one square mile on the Yenangyat oil-field, numbered 1 to 21 A to G, 



and these blocks extend seven miles north of Yenangyat. 



Of the country round and north of these mapped blocks, the 

 only maps available were the J"= 1 mile Frontier maps. 



Previous to my examination of the Singu and Tangyi hills, parts 

 of them had been visited by Dr. F. Noetling, 

 and they have been described by him in Vol. 

 XXVII of the Memoirs of the Geological Survey of India. 



Coming now to the physical features of the country, we find 



that those parts of the hills, which are 

 Physical features. 



composed of miocene beds, are very different in 

 appearance from those composed of pliocene sandstones, as their 

 outward shape is governed by the weathering of beds dipping 

 at various angles, which resist the disintegrating influences at 

 different rates. The miocene hills are steep and rise sharply from 

 the surrounding country. They are composed of interstratified 



( 32 ) 



