STRATIGRAPHICAL FEATURES. 



35 



worked out in detail. Except the Barmer sandstones with their frag- 

 mentary plant remains, none of these newer rocks occur in the area 

 I have examined myself. No large scale maps of Jaisalmir territory 

 have been published, even the sheets of the Atlas of India being as 

 yet a blank as regards that part of the desert, and in the absence of 

 such maps, especially where the exposures of rock are so isolated, no 

 detailed work can be done. Mr. Oldham has given a sketch map of 

 part of the country lying to the north of Jaisalmir, and divides the 

 rocks into the following groups 1 ; — 



Period. 



Recent 



Name of groups. 



Alhivium and 

 sand. 



Blown 



Sub-recent . Amir shingle beds . 



Tertiary 



Mesozoic . / 



Nummulitic . 

 Abur group . 



Parfhar group 



Bedesir irroup 



Jaisalmir group 



Lathi group . 



Description. 



Patches of rolled pebbles of local origin ; possibly 

 marine littoral deposits. 



Limestones with nummulites and beds of Fuller's 

 earth (Multani mitti). 



Sandstones, shales and fossil iferous limestones, 

 the latter weathering dark red ("Ammonite bed 

 of Kucha"). Am. (Stephanoceras) opis, Sow,, 

 Area, etc. 



Soft white felspathic sandstones, occasionally 

 calcareous and sometimes ferruginous, locally 

 hard and glassy, weathering into a clean sugary 

 sand. 



Purplish and reddish sandstones with thin layers 

 of black vitreous ferruginous sandstone; a bed 

 of red calcareous sandstone contains fossils 

 resembling Katrol (Cutch) forms. 



Thick bands of compact buff and light brown 

 limestone interstratified with grey, brown and 

 blackish sandstone with some conglomerate. 

 Probably equivalent to the Chari 'Cutchl group, 

 Am. {Stephanoceras) fissus, Sow., Nautilus 

 Kumagunensis, Waagen, Terebratula biplicata, 

 Sow., Corbula lyrata, Sow., C. pectinata, Sow., 

 etc. 



White, grey and brown sandstorms interstratified 

 with numerous bands ofhaid black and brown 

 ferruginous sandstones and grit. Towards the 

 base soft argillaceous sandstone, streaked and 

 blotched with purple Fragmentary plant re- 

 mains and pieces of dicotyledonous wood. 



1 Rec. Geol. Stirv. Ind., Vol. XIX, Pt. 3, p. 157. 



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