230 
W. F. Cole. 
POISON HILL 
D Uppei" greensand 
CINGIN 
Geologieol 
boundoriet 
rossiliPerous 
cbolK outcrops 
• -* ^ V*^- 
A- WOORGOP 
Miles 
Figure 1, 
Geological sketch map of Gingin. Drawn by F. R. Feldtmann and reproduced 
from “Junior Geology.” 
were possible but Poison Hill was selected because it is the highest point in 
the district and tlms offers least cliance of contamination of the covering soih 
Moi’eover a landslide on the southern slopes of the hill pro\'i<led a vertical 
section from which three samples representing ( I ) soil, (2) subsoil and (3) tipper 
greensand could bo taken in the same profile (Fig. 2). Because the various soil 
horizons are clearly differentiated it is believed that tlio landslide has not 
affected the main body of the hill, and that natural contamination is neglig- 
ible. X-ray evidence indicates a zoning of mineraLs to be expectetl from 
■weathering in situ. Artificial contamination vould therefore appear to be 
also negligible. 
Professor E. de C. Clarke anrl Dr. D. Carroll of the Department of Geology 
of the University of Western Australia supervised the collecting of the samples. 
