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BULLETIN OF THE NATURAL HISTORY SOCIETY. 
88. — On Geological Boundaries in the Tuadook-Walkemik 
Region. 
Read December 6, 1904. 
The geological boundaries laid down on our geological maps 
are, in much of the Central Highland region, necessarily largely 
conjectural. These parts have been little visited, in some large 
areas not at all, by geologists, and so completely is that 
country drift-buried and forest-covered that ledge-exposures are 
very hard to find. During three visits to the area shown on the 
accompanying map, I have noticed ledge rock in the places indi- 
cated by the symbols. These facts will necessitate a considerable 
change in the boundaries represented on the published maps, but 
