THE ARCH^AN FORMATION OF THE ABUKUMA PLATEAU. 533 



It ]nay ii«)t be out oi ])lace to .speak sliortly aJ)out the n(jiiieiid;i- 

 tiire. It has now become ahiiost an imperative duty for petroJo^iists 

 io .separate .sli;ir])ly tlie grauitcH ïvoin the (jneissc.'i. Prof. Colien' 

 loii^' aii'O j)oitited out tliat 1)y gnei.s.s we luider.staiid a u'euuine struti- 

 form r(X'k ; and info «ueli a rock granite i.s ne\er transformed, however 

 [•erfectly tlie hitter niay .show the .scliisto.se structiu'e. Such rock is 

 properly (o be de.siu'nated sc^histose uTanite. As uTanites ;ind li'neis.ses 

 are ueolouical Ijodies ijeneticaNv (piite dilferent, so and)i_ii'uous 

 Jiames bke uTanite-gnei.ss und ^ü;jiei.ss-L»ranite, ,<j;'iven to the metamor- 

 phosed njcks, had better l)e totally ex])elled for ever from petrou'raphical 

 literature. I follow the good exami)le of Prof. Cohen, and call 

 hereafter such dynanio-metanioi'pliic products scJiistosi' oranite^. In 

 order to avoid confusion, this is lundamentally nece.ssarv for a country 

 like Japan, where these schistose rocks are so largely developed, 

 occurring side l)y side with genuine gneiss, as fa* example, in the 

 southerii part of tiie Mutsu chain, in the moiuitaius oï Abukuma, 

 Akaishi, Suzuka, ivasagi, and Katsura, as well as in the northern [)art 

 of the South-Kiûshfi range'-'. I now returji to I he granite, namely : 



h) Imycrfcctli) Scliislosi^ Aiii/iJilhoh'-Granilc. 



As iius been alreadv ])ointed out, the transition to this is very 

 gradual, and there arises consecjuently a numlK'r of intermediate foians, 

 wiiich do not allow of biicf (diariicteri/.atioii. As we approacli the 

 scJiistose grani I e t'v(n\i n vejr'ioii oi^ II oriiui h rock, it is hardly perceptible 

 wliere one begins and tlie other ends. On large exposures su(;h 

 transiti(jnal r(3ck8 may be best seen by their petailiar habitus, somewhat 

 deviating from a normal structure. On t!ie other hand, specimen« 



1 Geognost. BescJir. d. Umfjegoid von Heidelberg, 1881; see also Ueber dax kryntallinische 

 Grundgebirge der Insel Boniholm. 



2 T. Haracla, Die Japanisdien Inseln, Tokyo, 1890, p. 46. 



