RED BED— SAIGHAN. 105 



lands " of the United States. The most abundant salts are car- 

 bonate, sulphate and chloride of sodium. For an account of 

 its nature and origin see W. Center, Rec, Geol. Surv., Ind., XIII, 

 253.. 1880 : H. B. Medlicott, ibid, 273 ; and recent references by 

 J. W. Leather in the Agri, Ledger. 



Rewah Stage. — The middle of three divisions of the Vindhyan (Upper 

 Vindhyan) system as proposed by T. Oldham (Journ, As. Soc. 

 Beng., XXV, 249, 1856). Named from the State in Central 

 India. F. K. Mallet {Mem., Geol. Surv., Ind,, VII, 27, 1869) 

 divided the Rewah series as follows : — 

 Upper Rewah . Upper Rewah sandstone. 



( Jhiii shales. 

 Lower Rewah . \ Lower Rewah sandstone. 

 ^Panna shales. 



Owing to the discontinuity of some of the beds, E. Vredenbnrg 

 (Rec, Geol. Surv., Ind., XXXIII, 254, 1906) proposed a new 

 grouping of the Vindhyans, placing the Rewah and Kaimur 

 together in a new series, the Tons series. 



Rhotas. — See Rohtas. 



Rohtas (Rhotas) Stage.— Name proposed by P. N. Datta (Rec, Geol. 

 Surv., Ind., XXVIII, 145, 1895) for the upper three beds of the 

 Lower Vindhyans distinguished by F. R. Mallet (Mem., Geol. 

 Surv., Ind., VII, 28, 1869). Named from the ancient fort of 

 Rohtasgarh (24° 37' ; 83° 65') in the Shahabad district. 



Saigbatl Series. — An extensive series of shales, conglomerates, 

 sandstones and coal beds in Eastern Afganistan, lying with 

 apparent conformity on the volcanic Helmand series, and resembling 

 certain Jurassic strata in Russian Turkestan and other plant- 

 bearing formations overlying Jurassic volcanic beds in the 

 Caucasus. The series has been named from the district of Saighan 

 (35° 10' ; 67° 45') by H. H. Hayden (Mem., Geol. Surv., Ind., 

 XXXIX, 30, 1911), who has identified the fossil plants pro- 

 visionally as similar to those from Russian Turkestan 

 described by A. C. Seward (Mem,, Com. Geol,, Russ., New Ser., 

 LIV, 38, 1907) as Jurassic. Hayden has shown (loc cit., 31-33) 

 that similar beds in Western Afghanistan described by C. L. 

 Griesbach (Rec, Geol. Surv., Ind., XIX, 245, 1886) as Lower 

 Gondwana were correlated on inaccurate data, and that the 

 Saighan series belong to Angaraland, not to Gondwanaland. 



