BY R. M. JOHNSTON, F.LS. 137 
conclusion formed by him; for, in this respect, he simply 
follows and adds weight to the original conclusions of Messrs. 
Gould, Milligan, and Strezelecki, against whose judgment, as 
to age of greenstone, I have always felt myself to be in an uncon- 
genial atmosphere of opposition, even when that opposition, 
as so frequently expressed by me, is both very doubtful and 
only at most ¢entative. This attitude.on my part is only 
natural, when it is considered that, in my ideal section from 
Dry’s Bluff to George Town, published in this Society’s 
Journal* twenty years ago, I then followed Gould and 
Strezelecki, in regarding the greenstone of the Great Plateau 
as younger than the Permo-Carboniferous and Mesozoic 
sedimentary formations. Owing also to Mr. Officer’s imper- 
fect acquaintance with local sources of information relating 
to Tasmanian Geology, he has, in his small chart of 
Lake St Clair, unwittingly, reproduced a fac simile of a frag- 
ment of a geological “Map of a portion of Western 
Tasmania,’+ explored durmg the summer of 1860 by 
an expedition under the command of Charles Gould, B.A., 
F.G.S., Government Geologist (lithographed and coloured by 
F. Dunnett, of Hobart). That it simply reproduces a fragment 
of the geological and physiographica! details of this region of 
the west of Tasmania as originally mapped by Gould, is best 
appreciated when I meution that this scarce, but locally well- 
known, coloured geographical map of Mr. Gould, embracing 
the portion mapped and coloured by Mr. Officer, and agreeing 
with it perfectly in all essentials, covers an area of about 
2,500 square miles, situated between Cradle Mountain and the 
Mount Murchison region in the north, and between Lake St. 
Clair and the Mount Lyell region ia the south. When Il 
state that Mr. Officer’s chart is a less perfect delineation or fac 
simile of a portion of the region, covering at most 234 square 
miles of the south-eastern portion of the area embraced in 
Mr. Gould’s more perfectly detailed geological map (that is, 
only 9°36 per cent. of the area) we may more easily appre- 
ciate how far the map of Mr. Officer falls short of the more 
extended original map of 1860, while, for obvious reasons, it 
also compares unfavourably with the latter in exactness of 
physiographical and geological definition. I say this is 
unfortunate, because, were it not for the original elaborate 
and comprehensive geological map of Mr. Gould, Mr. Officer's 
smaller chart of a portion of the region would, unquestion- 
ably, be considered a most meritorious delineation, regarded 
as the result of the unaided observations of a geologist 
who had briefly examined the country for the first time. 
*Proc. Roy. Soc. of Tas., Aug ,1872 ‘‘Composition and extent of Tertiary beds 
in and around Launceston.” 
t Scale, 23 inches to the mile 
