ox THE SO-CALLED CKYöTALLlXE SCÜlSTä OF CHiL'UiUU. 137 



Explanation of Plates II -V. 



Plate II. 



This plate is devoted to the illustration uf some of the moat 

 characteristic structures of the rocks and also peon liar habits of the 

 minerals composing the Sambagawan schists. 



Fig. 1. — A transverse section of the fßaucophanc-schiü from Otaki-san 

 near the city of Toknsima, in the province of A^va, Island of 

 JSikoku. This may serve as an admirable example of an in- 

 ternal flexure of schists, in which a quartz stratula of a homo- 

 geneous appearance is intercalated between thin layers built 

 up of sericite and glaucophane. The originally horizontal 

 and parallel bands have suffered minute foldhigs, simul- 

 taneous with the mass-motion of the earth's crust ; and this 

 movement has brcnioht about the o-runulation of the homo- 



O O 



geneous quartz-bands, as may be seen m the drawing, es- 

 pecially at the turning point of the plicature (page 85). 



Fig, 2. — Brings to view, how the periphery of the felspar-nodules in 

 the normal sericite-gneiss has grown together with the quartz 

 grains so as to produce the psciido-pcgmatic structure ; this 

 figure also illustrates well the simultaneous crystallization of 

 the quartz, and the marginal portion of the felspar (page 88). 



Fig. S. — Gives an instructive example of somewhat porphyritic felspars 

 in a sericite-schist. Felspars are remarkably rich at their 

 centres, in the interpositions of iron-mica, iron-glance and 

 rutile, and are fringed with green, lamellar fibrous scales of 

 sericite. The same interposition and trimming recur in nearly 

 all the felspars of porphyritic habitus throughout the rocks of 

 the Sambagawan series (page 88). 



