1810.] Geological Fo7^mation of the Himalayan Mountains. 335 



slate. If may be seen of a still finer quality, and in still larger slabs 

 on the ascent to Choor. In many places, nodules of quartz are seen 

 imbedded in clay-slate, and in some places this is found passing into 

 micaceous schist. Copper is found in it, in the neighbourhood of 

 Khalsee. 



Limestone. — In the ascent to Mussooree, alternating with the clay- 

 slate, we find Limestone, usually compact and hard, but often honey- 

 combed and cavernous, bluish in colour, passing to grey, whitish and 

 chalk-like in some places, and becoming in others even black. It occurs 

 first at Jureepanee, and then at the top of the range; it is also met with 

 at Sahunsudhara, alternating with clay-slate and dipping east. It is 

 found also in the Suen range, in the Kaphnul valley, as well as in that 

 of the Riknal, and very conspicuously, and of enormous thickness, and 

 over-topping the cla^^-slate, at Deobund. It is not, however, found con- 

 stantly alternating wiih the clay-slate, even in the range which inter- 

 venes between the Jumna and Ganges rivers, as it is wanting near 

 Budraj ; also between Landourand Surkunda, though very abundant in 

 the neighbourhood of Dhunoultee, one of the places which the Author 

 recommended as an excellent site for a Sanatarium. The Limestone, 

 though in such enormous, apparently amorphous masses, is rather par, 

 tially diffused, when compared with the Clay-wlate. Sometimes it is 

 harder, and even non-effervescent, becoming also siliceous, and like 

 chert; though the pure blue limestone, in connection with clay-slate, is 

 the most common. In some situations it passes into beautiful calc spar, 

 as at Dhunoultee; in others, into white saccharine Limestone, formed 

 of large crystals, as in some places in mica slate and gneiss, as well 

 near the granite of the Choor Mountain, and of Gungotri. Gypsum is 

 found associated w'ith the Limestone in some situations, as at Sahun- 

 sudhara, below Mussooree, and at Jureepanee, v. Herbert and Cautley 

 (As. Res.) Heavy Spar, or Sulphate of Barytes, is found in the ascent 

 to Landour, of which, as well as of the rocks, specimens were sent by 

 the Author to the Asiatic Society in 1828. The sulphurous spring iti 

 the vicinity of Sahunsudhara, with the dripping rocks and numerous 

 stalactites hanging down from the roof of the cavernous limestone, 

 with the leaves, &c. encrusted with carbonate of lime, have often at- 

 tracted the attention of, and been described by travellers. 



QuARTZOSE Conglomerate.-— The Clay-slate formation is, in many of 

 the peaks, surmounted by strata of a rock which Mr, De la Beche has 

 denominated Quartz conglomerate. It varies much in appearance, 

 being light grey coloured on Landour, coarse-grained and reddish on 



