236 Proceedings of Philosophical Societies. [March, 



Other primary rocks, granite, gneiss, mica slate, and clay slate, 

 and in a few places granular limestone, are occasionally observed. 



Dolomite, of a bluish-grey colour, is commonly used for 

 building in the vicinity of Ambire and Taypore, and the white 

 marble of Mokranna, about 35 miles north of Aj mere, is remark- 

 able over all this part of India. 



About 14 miles west of Ajmere, the primary tract is succeeded 

 by a country comparatively plain ; from within which, the pri- 

 mary range is seen extending to a considerable distance towards 

 the north, and to the west of the south. This plain is diversi- 

 fied by sand hills, with clay in the hollows between them, and 

 occasionally by barren high banks of hard clay mixed with 

 " kunken," a term applied by the author to a peculiar sort of 

 calcareous concretion, which he has not described in detail. 

 The basis of the flat country seems to be sandstone of several 

 varieties, but in general of a dull reddish hue ; the beds some- 

 times rising into hills 300 or 400 feet in height. In several 

 places all the buildings are formed of this reddish stone, and it 

 colours all the water in the tanks. The sand appears to have 

 been formed of the detritus of this rock. 



Within the flat country, north and west of the primary moun- 

 tains, many salt lakes occur, one of which, that of Sambur, 

 north-west of Jaypore, supplies nearly the whole of Upper India 

 with salt ; the waters becoming impregnated during the rainy 

 season to such a degree, that when the lake dries up, the salt is 

 found crystallized in abundance under the mud which it 

 deposits. 



The hills about Joudpoor, the most western point to which 

 the author's course extended, occupy a considerable space to 

 the north, west, and south of that place, and are of very differ- 

 ent appearance from those above described. They consist of 

 claystone porphyry, which appears to repose on the sandstone. 



In returning towards the south-east, *' dentated peaks" of 

 quartz were seen about Pahlee, and the country became more 

 fertile ; and in crossing the mountainous range already men- 

 tioned, about 70 miles south of the neighbourhood of Ajmere, 

 the rocks were still found to be principally quartz, the peaks of 

 which rose to about 2000 to 2500 feet above the plains to the 

 west. The plateau in general in this place being about 700 to 

 1000 feet above the country immediately on the south. 



About Odeypoor, the quartz lies upon reddish granite, which 

 continues for some miles to the east, and is succeeded by a low 

 range of quartz, extending to 50 or 60 miles from Odeypoor ; 

 after which no more primary substances were seen. Beds of 

 compact limestone occur just below this quartz range, and 

 occupy apparently a tract of considerable extent in the vicinity 

 of Neymutch. 



In this vicinity also, low hills, like artificial mounds, are 

 observed ; the commencement of the extensive basaltic district 



