211 
EXPLANATIONS OF PLATES. 
Microphotographs of various types of quartzites described in 
56 foregoing paper. In all cases the magnification is 15 dia- 
meters. 
PLATE XXXIII. 
Fig. 1. Mitcham (i.). Crossed nicols. Тһе particular point 
photographed is somewhat poor in felspar. Shows the com- 
pletely interlocking arrangement of grains. 
. Figs. 2 and 3. Maitland Bore (xiv.). Fig. 2. is in ordinary 
light; fig. 3 the same portion of the section between crossed nicols. 
Show the very marked rejuvenescence ‚of the quartz grains. In 
fig. 2 the outlines of the original grains are marked clearly by 
the rings of inclusions. In fig. 3 the optical continuity of the 
quartz outside these lines with that inside is apparent. 
Fig. 4. Mr. Dinham’s Farm, west of Ardrossan (xv.). Crossed 
nieols. Shows well the perfect rejuvenescence of quartz crystals 
and the infiltration with chalcedonic cement. 
Fig. 5. Plain east of Mount Remarkable (xviii). ^ Ordinary 
light. Quartz and composite grains set in a fine base. The whole 
rock is crossed by a series of parallel, secondary solution-planes. 
Fig. 6. Sellick’s Hill. Crossed nicols. Show undulose extinc- 
tion and marked tendency to cleave. 
PLATE XXXIV. 
Fig. 1. Waterfall Gully (xxvii.). Ordinary light. Small rhom- 
bie sections, probably lazulite. 
Fig. 2. Field River, near Hallett’s Cove. Crossed nicols. In- 
dicates irregularity of texture, strain phenomena, felspathic na- 
ture of rock, and (rather faintly) fibrous structure of calcareous 
cement, 
Fig. 3. Inman Valley. Boulder from conglomerate gneiss 
(xxxv.). Ordinary light.  Felspathic content and marked schis- 
tosity are shown. 
Fig. 4. Inman Valley. Ground mass of conglomerate gneiss 
(хххуі.). Crossed nicols. Shows the foliation of the rock and! the 
optical evidence of strain, but does not exhibit well the “augen” 
structure. 
Fig. 5. Lake Eyre District. Desert sandstone (xxxvii.) Angu- 
lar quartz, set in a fine-grained ground mass, somewhat chalce- 
donic. 
