4T 
taken place by the infiltration of silicated waters into an open 
an m d : : 
d porous rock, causing great induration within certain 
geological age of the rock, they may occur in any country 
and of any age when the suitable conditions for their formation 
exist. Sarsen stones of this type are widely distributed 
throughout South Australia. They have not attracted the 
same attention from the public here as those of England, from 
the fact that in England they are rendered conspicuous 
nR ; c 
oce 
like the grey-wethers of southern England. They can be seer 
from the railway train near Yacka, and at Stone Hut, and in 
grains, closely dovetailed and united together by a siliceous 
cement. On account of this form of structure they exhibit a 
Same descriptions. In most cases a different form of silicifica- 
tion can be recognized between that of the siliceous quartzites 
of Cambrian Age and the siliceously-cemented river sediments 
that have made the sarsen stones. T am c l 
&lve evidence of metamorphic action, while the indurated 
Tiver sediments do not. In the case of the metamorphic 
bo (9 Howchin: “Notes on the Geology of Ardrossan and Neigh- 
LN" Trans, Roy. Soc. S. Austr., v. 42, 1918, pls. xxii. to 
i 
