TERTIARY. 



311 



appears on the map attached to this Memoir, and leaves 

 it just below Hsunkwe by a narrow, though not deep gorge 

 in the Plateau Limestone. The floor of the valley consists 

 partly of the limestone and partly of the Namyau sand- 

 stones, and not only do the silts cross the boundary between 

 the two formations without interruption, but they also 

 traverse in the same way a strong fault, which crosses 

 the river close to the ford north of Lashio, and is 

 marked by a line of hot springs. The beds consist 

 of sandy silts and soft sand-rock with very subordinate 

 , pebble bands and an occasional layer 



Lithnlngical characters. , . - . . . " 



oi harder ferruginous sandstone ; but- 

 even these are only indurated near the surface, where 

 the iron oxide in them is concentrated. They form 

 low rolling hills covered with grass and very scattered tree 

 jungle, traversed by numerous sluggish watercourses. 

 Outcrops are only to be seen along the course of the 

 river, the northern boundary being entirely concealed 



by rainwash from the surrounding 



Position of coal The ^ ^ f ^ strata 



Sett III a . o i 



exposed along the river is to the 

 north, and since the coal seams are confined to the lower 

 portion of the formation, they are only to be seen 

 in the river bed or close .o it in a few of the deeper 

 ravines. 



(iii) The Namma field. This is perhaps the most important 

 of the Tertiary basins, as it contains the most promis- 

 ing coal seams, though the inferiority of the coal, and 

 the distance of the fieJd from the railway, make it 

 unlikely that it will ever be worth while to exploit the 

 mineral. The field extends along the north bank of the 

 Nampawng, from its junction with the Namma near the large 

 village of the same name (H 2), for a distance of about 

 15 miles, with an average width of 3] miles. This 

 area differs from that of Lashio in being covered for 

 the most part with dense forest, which rendered the 



task of prospecting very difficult. 

 Lit holoj-ical charac- mi i i i i :• v 



tera ° Lne beds also exhioit- a greater 



variety than in the Lashio field, 



the grey sandy silts being subordinate, while there is a 



