1869.] Geological Notes on the Khasi Hills. 15 



Echini. Keeping to the well defined boundary of the limestone, I 

 met with a well marked unconformity of the two series running in 

 a line, from south-east to north-west, and at a short distance further 

 on, from north to south. The limestone terminated in a perfect cliff, 

 and not a single particle was to be found on the sandstone side 

 of the depression between the two. In these depressions blocks 

 of the sandstone were found resting on the limestone irregular surface, 

 and the former also rose in a rounded hill considerably above the 

 general level of the latter. I give a sketch, (Plate VII) and a section 

 (Plate VIII) of this upper junction. The local unconformity of the 

 rocks clearly shews, that the sandstones have been here deposited 

 around and against an old cliff of the limestone rocks. The section 

 exposed in the same ravine, showed it was no result of local 

 displacement. 



In some new clearings, close under the trigonometrical station of 

 Nongkulang, and on the north side some good sections are to be seen 

 of the relative positions of the limestone and superincumbent sand. 

 The first and highest bed of the nummulitic limestone series, is a 

 peculiar dark burnt, umber-coloured calcareous rock, containing scat- 

 tered very small Nummulites. In a ravine close by the light-coloured 

 pure limestone was seen to pass horizontally into the hill. Great 

 hollows occurred in the surface, where the limestone had evidently 

 fallen in, and the ravine first mentioned entered into one that was 

 of great depth. 



Proceeding from Nongkulang south along the path to Shibak, one 

 passes over a steep scarp of some 50 feet in the upper sandstones (fossils 

 numerous), which extend some distance to the bed of the first consider- 

 able ravine. Nummulitic limestone occurs here again, and following it 

 up in the section represented on plate VIII, it is seen close to the path, 

 being a hard blue clay {w) ; it contains hard nodules of the same material, 

 its thickness varryingfrom eight to ten feet. This accords, in its charac- 

 ter, with Section d, see plate VI ; above r is a great thickness of white 

 pure nummulitic limestone, continuing up the face of the hill. Below 

 the blue clay, following down the ravine, is a darkish purple earthy 

 rock (three feet), it effervesces slightly with acid ; then follows a bed 

 of a dark brown rock, having minute white Nummul it es scattered through 

 the mass, and being interstratified with some light-coloured beds, the 



