26 MEDLICOTT^ SHILLONG PLATEAU. 



more than 100 yards from the coal there is not a vestige of this to 

 be found. The extension to the north must be equally limited^ for 

 within a short distance the Shillong series occupies the whole ridge. 

 It does not seem either to reach far to the souths for it has not been 

 discovered at many points where its horizon is exposed. The great 

 abundance of pyrites is a serious drawback to this coal. 



The bottom rock as characterised by coarse conglomerate is re- 

 stricted to the region of the plateau^ and approximately to where it 

 rests upon the crystalline and metamorphic series. Within this area 

 I only know of one exception to this rule : on the path descending to 

 the village of Maplai in the valley of the Bogapani^ the only strong 

 band of coarse conglomerate occurs well above the base of the creta- 

 ceous series ; and here it has the exceptional character that all the large 

 debris is thoroughly water- worn. It is underlaid by some 200 feet of 

 coarse massive sandstone. In all the sections to the south of the main 

 scarp, and where the stratified trap is the supporting rock there is 

 little or no vestige of conglomerate. The feature formed by the bottom 

 rock here, at the base of the range, is also remarkably constant 

 for a considerable distance. All the large rivers cut a deep narrow 

 gap through a coarse sandstone more or less felspathic and ochreous ; 

 it is over 200 feet thick without a single continuous line of stratifi- 

 cation ; and has a high southerly dip. In the section on the Theria 

 river there is a considerable blank before the underlying trap appears ; 

 but in the Bogapani, and in the Jadukatk (Umblai), the feature is 

 exactly similar to that at Theria, and the actual contact of the massive 

 sandstone with the trap is seen, without any conglomerate. This massive 

 sandstone is continuous with that which overlies, and for a short space 

 interstratifies with, the conglomerate at the higher levels ; and the base 

 of it may be supposed contemporary with the nearest conglomerate. 



In the Jadukata, or Umblai, a little above its debouchure into the 

 plains near Laour, I found a fossihferous band in a position that I 

 ( 176 ) 



