THE METAMORPHIC ROCKS OF ADELIE LAND . STILLWELL. 207 



2. The variation in the crystal grain size in the same type of metamorphic rock, 

 illustrated by 



(a) Plagioclase pyroxene gneisses at Cape Gray, Madigan Nunatak, and Aurora 



Peak, with average absolute grain sizes 0-05mm., 0-30mm., 0-17mm. 

 respectively. 



(b) Coarse and fine amphibolites (No. 9 and No. 629), at Cape Denison, with 



average absolute grain sizes l-5mm. and 0-22mm. respectively. 



(c) Coarse and fine biotite felspar gneisses (No. 144 and No. 146), at Cape 



Denison, in which the absolute size of the felspar may vary from 0-30mm. 

 up to 27mm. 



3. The existence of rocks which have been described as metamorphic differentiation 

 products 



(a) Chlorite rock. 



(6) Epidosite. 



(c) Biotite hornblende schist. 



(d) Bands and lenses of pure hornblende or felspar, associated with the coarse- 



grained amphibolites. 



(e) The nodular zones of magnetite, sphene, and felspar in the amphibolite 



(No. 143). 



4. The existence of the rocks which have been described as metamorphic diffusion 

 products 



(a) The indefinite junction between some amphibolites and the granodiorite 



gneiss at Cape Denison, with the formation of hornblende and biotite 

 gneisses. 



(b) The apparently sharp junction between amphibolite and granodiorite 



gneiss illustrated in the specimen No. 372, collected from the moraines 

 at Cape Denison, in which the amphibolite and gneiss are separated 

 by a zone of biotite felspar gneiss 1cm. wide. 



(c) The observed passage between some of the aplite gneisses and amphibolite 



at Cape Denison. 



(d) The change of the thin threads of original basic dyke into biotite felspar 



gneisses at Cape Denison. 



(e) The observed passage between cyanite garnet gneiss and amphibolite at 



Garnet Point. 



5. In the recrystallisation of the primary augite of the basic rocks in the Cape Gray 

 dyke series the segregation of the ilmenite involves the transmission of material through 

 solid crystalline material. 



