20 Geological Notes on the Khasi Hills. [No. 1, 



limestone occurs in great thickness, the total being perhaps 250 feet. On 

 this ascent I came on detached pieces of the fossiliferous iron-coloured 

 clays. Next in order came the nodular ferruginous sandstones, noticed 

 also below Nongkulang on the northern side, and then again some 40 feet 

 of limestone. The topmost bed of this rock was of a brown umber colour, 

 the Nummulites were small and much reduced in number, with here 

 and there a faint trace of a shell ; shales, and sandstones with precisely 

 the same fossils as I had found on Nongkulang ridge, then succeeded. 

 The base of Yindkii was quite 1 J miles further along the ridge ; where 

 an ascending series of the beds is first noticed, they at once become 

 much lighter in colour, and coarser in texture. With this change the 

 fossils become scarce, at last only an occasional bivalve is to be found, 

 and these soon disappear altogether, thin shalely beds intervene, and 

 at the top of Yindku itself, the rock was soft, sandy, and friable. The 

 thickness of these newer deposits is quite 200 feet, the dip now being 

 very low to N.W. Yindku from its isolated position, and greater 

 height than any of the hills around, formed an excellent point for 

 observation, but being covered to the very top with large timber trees, 

 would be of little use without a maichan. From the one built there, 

 the view was most commanding, extending to the very foot of the 

 hills in the Mymensing district. 



On the spur thrown off from it, to the east, a like section to that first 

 described, occurs again, and the best spot whence to visit it is Shibak, 

 situated on the direct road from Nongumlai to Bagoli in the plains. 

 After leaving the main ridge of Tigasin near Nongumlai, a quarter of 

 a mile of descent brings one to the Laokla stream flowing north. 

 Leaving this a ridge of the fossilferous beds is another stream, the 

 Umpernon, is crossed where they dip S. W. at a low angle ; on the 

 descent, the unconformity was again noticeable, although the beds still 

 retained their normal horizontality. After descending over a considerable 

 thickness of the nummulitic limestone, it suddenly is replaced by the 

 ochre-coloured sandstones, at the foot of an ascent extending to a height, 

 considerably above the lowest limestone just left. At half a mile, 

 limestones again dip north 5°, and at the bottom of the valley all was 

 of this formation ; near a huge overhanging mass of it, used as a 

 temporary shelter, it was seen to rest on a light coloured fine sandstone 

 (the cretaceous ?), the same sequence in every respect as is seen near 



