18 HOLLAND AND TIPPER : INDIAN GEOLOGICAL TERMINOLOGY. 



Aravalli system Named by C. A. Hacket (Rec, Geol. Surv., Ind., 



X, 84, 1877) from the Aravalli hill-ranges in Rajputana. 

 Originally the system included the Manclan, Ajabgarh and Alwar 

 series, but some of these were excluded afterwards and included 

 in the Delhi system (R. D. Oldham, Manual, 2nd Ed., 1893, 

 67, 68). The system so limited includes quartzites, calciphyres, 

 hornblendic and mica schists, with andalusite, staurolite and 

 garnet, felspathic schists and gneisses. The schists are 

 traversed in places by granite-veins. The relations to the Delhi 

 system have not been satisfactorily established. 



Archaean group. — In India, as in its own home, America, and 

 in Europe the name Archaean suggested by J. D. Dana in 

 1872 (Amer. Joum. Sci, 3rd series, Vol. Ill, 179, 250) to cover 

 all rocks below the known Cambrian base has been given 

 various meanings. The fundamental crystalline complex, which 

 is such a conspicuous feature in Peninsular India especially, 

 was referred to occasionally during the eighties as Archaean, 

 especially after the International Geological Congress of 1885, 

 when it was agreed to use the word Archaean as a group 

 name to include the various pre-Cambrian systems. Probably 

 the first precise application of the term to Indian rock groups 

 was by R. B. Eoote (Mem., Geol. Surv., Ind., XXV, 26, 1895), 

 who limited its meaning to the gneissose and granitoid members 

 of the crystalline complex, excluding the rocks of the Dharwar 

 system, which he regarded as distinctly younger than the 

 gneisses and gneissose granites. This use of the term coincides 

 with that which developed in the United States (after the 

 invention of the term Algonkian to cover the systems of 

 unfossiliferous pre-Cambrian strata) as expressed by C. R. Van 

 Hise in 1892 (Bidl. U. S. Geol. Surv., No. 86, 13) ; that 

 is, applying the name Archaean to " granitic gneissic and 

 schistic rocks, among which are never found beds of quartzite, 

 limestone, or any other indubitable elastics." In 1906 T. H. 

 Holland (Trans. Min. and Geol. Inst., Ind., I, 47) grouped the 

 Dharwars with the fundamental crystalline rocks as Archaean, 

 drawing attention (Imper. Gazetteer of India, New Ed., 1907, 

 57) to the great " break " which separates the gneisses, schists 

 and Dharwars from the much younger, unaltered Cuddapahs 

 and other unfossiliferous rocks of the Peninsula, while some of 

 the""gneissose rocks were regarded as eruptives probably younger 



