Speight. — Geology of the West Coast Sounds. 265 



Marshall (14) notes, with descriptions, gneisses and hornblende schists 

 from Milford, but he has devoted special attention to the basic rocks at 

 Anita Bay, on the southern side of the entrance to the Sound. He has 

 recorded from there hornblende schists and gneisses, boweuite, dunite, 

 and harzburgite, the last-named passing into marble. Finlayson (3) has 

 also referred to the bowenite, and the matrix in which it occurs. This 

 locality, owdng to its remoteness and the thick covering of bush, is very 

 imperfectly known, and the present author was able to collect a number of 

 other rocks mostly from boulders which can only have come from the ad- 

 jacent hillsides ; but the marble passing into harzburgite was fomid in posi- 

 tion as veins in a dark indistinctly foliated rock at the western point of 

 the bay. The following types were met with, and will serve to emphasize 

 the remarkable variety of rocks occurring there, and the difficulty of fully 

 establishing their true relationships. 



Hornhlende Garnet Gneiss (An. 1). — This is a markedly schistose rock, 

 with many garnets visible to the eye. Under the microscope it is composed 

 of large irregular reddish garnets, with quartz (probably quartz de corrosion) 

 and rutile inclusions. There is a considerable amount of greenish horn- 

 blende, and some flakes of brown mica. Much quartz occurs in rounded 

 grains with undulose extinction, and feldspar (andesine) frequently exhibit- 

 ing wavy and broken twin lamellae. Zoisite occurs, very occasional epidote 

 and muscovite, and much brown rutile in grains included in the garnets 

 and mica. 



Hornhlende Garnet Gneiss (An. 9). — A dark, even, fine-grained rock, 

 showing in section much garnet in grains, and the minerals of the pre- 

 ceding rock, but the texture is much finer-grained and shows the effects 

 of pressure. The biotite flakes are bent round the larger elements in pseudo- 

 fluxion structure. 



Garnet Gneiss (An. 10). — -This is a pink-grey distinctly schistose rock. It 

 contains much garnet in grains, with inclusions of quartz and feldspar some- 

 times closely resembling graphic intergrowths ; the garnet is cracked, and 

 has both muscovite and biotite freely developed in the cracks. Flakes of 

 both these micas occur, and much quartz and feldspar twinned and un- 

 twinned ; apatite needles are occasionally to be seen. Pressure granulation 

 is very prominent. 



Diorite Gneiss (An. 14). — -A rock showing much dark-green hornblende 

 and feldspar, distinctly foliated. It contains much greenish and bluish- 

 green hornblende, passing into chlorite and epidote ; plagioclase, and some 

 quartz. Another variety (An. 15) of this gneiss contains long needles of 

 epidote, and flakes of muscovite included in the feldspar. 



Hornhlende Garnet Gneiss (An. 11). — This is a distinctly foliated rock, 

 composed of much hornblende frequently intergrown with garnet, garnet 

 in grains, some faintly pleochroic epidote, columnar aggregates of zoisite, a 

 little brown mica and muscovite, quartz and much plagioclase, brown grains 

 of rutile. 



Dunite (An. 5). — This is similar to Marshall's rock, but it contains occa- 

 sional enstatite as well as diopside. The structure is markedly cataclastic. 



Harzburgite (An. 3, 4, 6, 7). — Some of my specimens are similar to those 

 described by Marshall (13), but others contain much augite with occa- 

 sional diallage structure. The olivine is partially serpentinised, and appa- 

 rently passes into talc, as flakes and aggregates of that mineral occur 

 frequently, and specially as inclusions in the carbonate present in the rock. 



