The Geology and Physiography oe the Lawnswood Area. 
55 
Table 1. 
comparison of STRATIGRAPHICAL SrcCESSION and thickness of the 
JIMPER pING SERIES IN THE LAWNSWOOD AND TOODYAY AREAS. 
Lawnswood Area. 
Toodyay Area. 
No. 
Horizon. 
Thickness 
Horizon. 
Thickness. 
Lower metasediments 
and hornblende 
Lower metasediments and 
hornblende 
schists. 
schists. 
1 
Quartzite 
unknown 
2 
>Not represented 
Hornblende schist 
35ft. 
3 
J 
Quartzite 
650ft. 
4 
Lower granitic gneiss unknown 
Lower granitic gneiss 
5,400ft. 
5 
Quartzite 
300ft. 
Quartzite 
375ft. 
6 
Hornblende schist 
oOft. 
Sillimanite schist 
100ft. 
7 
Quartzite 
150ft. 
Quartzite 
570ft. 
8 
Hornblende schist 
70ft. 
Hornblende schist 
40ft. 
9 
Quartzite 
180ft. 
Quartzite 
110ft. 
Upper metasedimenis. 
Upper metasediments. 
10 
Upper granitic gneiss 
approx. 2,000ft. 
Upper granitic gneiss 
1,900ft. 
11 
Quartzite with some 
subordi- 
Quartzite 
500ft.. 
nate quartzose mica schists 
250-600ft. 
12 
Hornblende schist 
ISOft. 
Indication of hornblende schist 
13 
Quartzite 
60-200ft. 
Not represented 
14 
Mica schist and quartzite 1, 850ft. 
Andalusite — muscovite schist 250ft.. 
15 
Quartzite and mica" 
5 000ft. 4-? 
schist 
(Thickness may 
^be due to in- 
Not represented 
16 
Metajaspilites and 
competent fold- 
banded iron-ore 
ing) 
IV. PETROLOGY. 
The rocks are divided into two groups : — 
A. The Jimperdiiig Series. 
B. The younger igneous intrusives. ^ 
A. THE .HMPERDING SERIES. 
1. Metasediments. 
(a) Quartzites. 
These are coarse-grained almost pure <|uartz rocks with well defined! 
bedding on which corrugations or h~ lineations (19, p. 591) are developed. 
The Lawnswood quartzites are identical with those described by Prideir 
at Toodyay (23, pp. 88-94). 
(i) Tlie Upper Quartzites are characterised b^^ the presence of small 
(<0.1 mm.) pale green cln’ome-museovite idioblasts enclosed in the quartz 
grains and oriented parallel to the bedding. Felspar is not found in the 
main band of upper (piartzites in the west of the Lawnswood Area but 
is common in the infolded quartzite which is correlated with the upper 
quartzites on structural grounds. 
(ii) The Lower Quartzites are identical with those of the Toodyay 
Area and have been connected in the field. The chrome-muscovite grains 
