6 LA TOUCHE : GEOLOGY OF WESTERN RAjPUTANA. 



cases by the (entirely hypothetical) existence of deposits of rock 

 salt of Vindhyan or more recent age concealed beneath the alluvium. 



In the same number of the Records l Mr. Hacket gives a list of 

 useful minerals occurring in the Aravalli region, but the only mineral 

 mentioned as being found in Marwar is the well known* marble 

 of Makrana, and of Sarangwa, near Desuri in Godwar. 



The third paper, published in i88i, 2 describes the geology of the 

 Central and Eastern Aravallis, and of the country lying between the 

 Aravalli range and the meridian of Jodhpur. Mr. Hacket includes 

 the whole of the granitic rocks found to the west of the Aravallis 

 under the comprehensive term "gneiss". In reality there is no true 

 gneiss in this area, but there are two protrusions of granite of different 

 ages, differing widely in texture and composition. 



After describing the sections in the neighbourhood of Sojat, where 

 upper Vindhyan sandstones are seen resting with total unconform- 

 ability on the upturned edges of Aravalli schists, Mr. Hacket proceeds 

 to describe the Malani lavas near Jodhpur and their relations to 

 the Vindhyan sandstones resting upon them. The existence of a 

 conglomerate of rolled pebbles of the lavas at the base of the Vin- 

 dhyans is mentioned, and the former are referred doubtfully to the 

 lower Vindhyan period. A section in the hills north of Chanod is 

 described in which Malani lavas are seen resting upon some red 

 slate?, supposed to be Aravallis. I have visited this section, which is 

 the only one where Malanis are found actually in contact with any 

 rocks older than themselves, and convinced myself that the slates belong 

 to the Aravalli system and that the relation is one of complete uncon- 

 formability. This section will be again referred to subsequently. 3 



Two papers were published by Mr. Oldham in Vol. XIX of the 

 1886. Records, giving the results of a traverse of 



R. D. Oldham. Jaisalmir territory undertaken in 1885 with a 



1 Rec. Geol. Surv. Ind., Vol. XIII, Pt. 3, p. 243. 



* Ibid, Vol. XIV, Pt. 4. P- 279- 



* Infra, p. 19. 



( 6 ) 



