L122 The Geology of Central Australia. (November, 
range to the north is also constructed on the same plan. In the 
Everard range the doleritic rocks are better developed, but oc- 
cupy the same position and show the same variation in composi- 
tion and structure. The two ranges are in fact counterparts of 
each other. 
The Peake and Mt. Margaret chain has essentially the same 
structure, with the exception that the doleritic rocks are appa- 
rently wanting. The Archzean gneisses exist here in the form of 
crystalline schists, quartzites and limestones, and vary in charac- 
ter. The strike is north-east, and they dip to the north-west ata 
high angle. The schists are as follows: 
Mica schist—-Contains both muscovite and biotite. 
E alinic. 
4. Specular (Itabyrite) containing much hematite. 
c. Calcareous. 
Hydromica schist.—Containing margarodite in place of the muscovite. 
a. Garnetiferous. 
b. aT 
. Chloritic. 
Chlorite sr —Greenish-gray, 
a. arneti erous, 
ġ. Epido 
Hornblende seais idi of quartz and hornblende. Sometimes wholly of hom- 
ende. 
Actinolyte.—A tough, light-green rock. 
Intercalated between these beds of schist are strata of: 
Quartzite. 
a. Feldspathic (orthoclase). 
6. Micaceous (muscovite). 
c rmalinic. 
d. Hornblendic, 
pg .—A dark red rock, Jaspery. 
. Foliated hematite (micaceous iron ore). 
pee ~—Coarse grained, blue, clinking under the hammer. 
a. Pyritiferous, 
6, Graphitic, 
c. Micaceous. Ta 
of granite . 
Through these metamorphic rocks irregular masses ae : 
tas mee 
Musgrave range. The granite is more hornblendic, D as 
always present. It is much coarser in grain, and is por i . 
Veins of orthoclase of considerable size are present in it. a r 
Through the metamorphic rocks are also: (1) Qus 
bearing much pyrite. Near the surface this has been is 
