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some feet into the massive diabasic greenstone, similar in 
character to that forming the cap of Mount Wellington. It 
is further of significance that the absence of ary appearance 
of change of the mudstones at point of contact, and the 
porphyritic and coarse crystalisation of the upper surface of 
the greenstone as compared with that where the greatest 
depth was reached indicate that the mass of greenstone was 
not a later lateral thrust along the plane of the bedding of 
the mudstone, but in all probability the mudstones were 
originally deposited against and upon the greenstones of 
Mount Wellington soon after their eruption. 
In various places along the Coast line of the Lower 
Derwent, as I have already shown, many natural sections 
_ occur where the fossiliferous mudstones, unaltered at point of 
contact, without doubt, repose quietly in horizontal beds, 
which naturally fill up the uneven surface of the underlying 
older greenstone I have already exhibited a sketch of a 
very fine section, which continually shows this relation for 
several miles between Blackman’s Bay and Passage Point. 
One section in particular not only shows in an unmistakable 
manner that the fossiliferous mudstones are more recent than 
the main mass of the older greenstone upon which they rest, 
but that both are older than a minor dyke or sheet of green- 
stone of a somewhat similar character to the older. This in- 
trusive greenstone, after bursting vertically through the 
older greenstone and the lower beds of sedimentary lime- 
stone, suddenly bends back and forms a sheet about seven 
feet thick, running parallel and intercalated between the 
stratified planes of the marine mudstones and limestones. At 
Constitution Hill and Lovely Banks, towards the central 
part of the island, there are also two or three fine sections in 
the cuttings of the Main Road, clearly showing the Mesozoic 
sedimentary rocks reposing upon the older greenstone. On 
the other hand a splendid section at the head of Spring Hill 
as clearly shows that a massive greenstone (not basalt) has 
been erupted later than the carbonaceous sandstones of Meso- 
zoic age, as the greenstone mass forming the ridge at this place 
can be seen to have intruded through the former, dislocating 
the sedimentary rocks, and spreading over them in great 
massive caps. Itisclear therefore that there are greenstones 
anterior to the lowest members of the Carboniferous System, 
and similar intrusive rocks of later date than certain of the 
members belonging to the Mesozoic Coal Measures. 
I am however, at present, if anything, inclined to the 
opinion that the massive greenstones occupying the more 
elevated mountain ranges as well as the greater part of the 
dividing ranges within the system, have all been erupted 
prior to the deposit even of lower members of the Carbon- 
