40 TOUCHE : GEOLOGY OE NORTHERN SHAN STATES. 



The presence of graphite in the limestone might be considered 

 D , , ., as a strong argument in favour of attributing 



Presence of graphite. . . . . 



an organic origin to the latter, but since it 

 has been discovered that graphite occurs, apparently as an original 

 constituent, in some igneous rocks, 1 and is not uncommonly to be 

 found in Archaean gneisses and schists, it is not possible to rely on 

 its occurrence in these limestones as a proof of their having been 

 organically formed in the first instance, without convincing evidence 

 of some other kind, which is not forthcoming. Whether the 

 carbon was originally provided by organic matter or not, it is cer- 

 tain that it has been in a state of fusion, for according to 

 Holland, 2 the graphite in the limestone of Sagyin, which is identical 

 with that of the Ruby Mines, when heated after treatment with 

 fuming nitric acid, exhibits the phenomenon known as ' sprouting, ' 

 and this property has been shown by Moissan 3 to be confined to 

 graphite that has crystallised from fusion. 



It is, however, not at all necessary to call in the aid of or- 

 . , , ganisms to account for the formation of lime- 



Alternative hypothesis. , . , . ... 



stone strata, and there is nothing impossible 

 in the inclusion in a complex of sedimentary and igneous rocks of 

 Archaean age, previous to the existence in any form of living matter 

 on the earth, of bands of limestone. If, then, all these rocks were 

 subjected together to the action of intense metamorphic forces, it 

 is conceivable that the mineralogical changes that have taken place 

 have operated in a direction opposite to that supposed by Professor 

 Judd, that is to say, that the calcite, either in a state of fusion 

 or one akin to it, has invaded the surrounding gneisses, and has 

 converted the felspars into scapolites, the excess becoming crys- 

 tallised among the original constituents of the rock as calcite. 

 That the latter mineral may be fused, and invade the surrounding 

 rocks without decomposition, under certain conditions, has been 



1 J. Walther, On Veins of Graphite in decomposed Gneiss (Laterite) in Ceylon ; 

 Records, Geol. Surv. Ind., Vol. XXIV, Pt. l,p. 42 : Al. Lacroix, Gneissose Rocks of Salem 

 and Ceylon ; ibid, Pt. 3, p. 155 : H. Moissan, fitude du Graphite extrait d'une Peg- 

 matite ; Complex Reridus, Vol. CXXI, p. 538 : F. 1). Adams, Geology of a portion of the 

 Laurentian Area ; Ann. Report, Oeol. Surv. Canada, N. S., Vol. VIII, J, p. 36 : T. H. 

 Holland, Chamockite Series ; Memoirs, Oeol. Surv. Ind.,Vo\. XXVIII, Pt. 2, p. 152 t Siva- 

 malai Series, ibid, Vol. XXX, Pt. 3, p. 172 : T. L. Walker, Geology of Kalahandi State ; 

 ibid, Vol. XXXIII, Pt. 3, p. 14 : F. Cirkel, Graphite, its Properties, Occurrence, Re- 

 fining, and Uses; Ottawa (1907). 



2 Op. cit.. Memoirs, Geol. Surv. Ind., XXX, Pt. 3, p. 175. 



3 Loo. cit., p. 540. 



