152 Notes on the Geology and Physical t [No. 3, 



Its chief peculiarity now consists in the beds of dark purple hue, in 

 others so fine, white or chalky in appearance, that they might almost 

 be mistaken for the latter rock. Broken up and mixed with water it 

 is used largely as a whitewash for native huts. Sandstone now 

 forms the mass of all the elevated points in Jawai, and is conspicuous 

 near the dak bungalow, resting horizontally on the highly tilted 

 older rocks. On the hill mass of Chirmang, south of Jawai and the 

 Mantadu, its thickness has greatly increased, bringing in above the 

 conglomerate thinner and finer beds, and less sandy in composition. 

 Here we find traces of the carbonaceous shales and in places a dark, 

 hard, earthy coal, invariably thin-bedded and altogether very local 

 in its distribution. To the east of Latuber the same features may 

 be seen all the way to Satunga, the metamorphics appearing on the 

 higher parts of the plateaux, where the sandstone only occurs in isola- 

 ted thin patches. 



But at Satunga, we are introduced to a new series altogether, 

 viz. the limestone (numnmUtic), of which an outlier forms a 

 mass with low perpendicular and jagged sides to the right of the 

 road, and on the very edge of the southern depression of the level 

 of the country. To the south-west one or two wooded isolated 

 knolls shew the limits of the northern extension of that rock. It 

 rests in this locality on the sandstones also associated with coal beds ; 

 and there is no doubt that these last are of secondary age, the proto- 

 types of rocks better developed under Cherra Poonjee and thinning 

 out at Maobelarkar, on the road to Shillong. There is also an appear- 

 ance of a break in the succession between these secondary strata and 

 the nummulitics, pointing to a long lapse of time, and to very differ- 

 ent conditions of the surface, before the deposition of the limestone 

 began. Here we are I think also near the confines of the tertiary 

 sea in which those rocks were formed, as shown by the thinning out 

 northwards of the limestone beds. 



Proceeding south to the low range of hills of which War Hill Station 

 forms the highest point, the limestone has greatly increased in thick- 

 ness, and is superimposed at the same time by beds of quite a different 

 mineralogical character, being nodular, ferruginous and highly fossi- 

 liferous. Above this well marked horizon no limestone with Nwn- 

 mulites was seen ; local unconformity of these last is noticeable, and 



