11 
rii'nci'u prevented more detailed observa¬ 
tion by the members of the Tasmanian 
Field Naturalists’ Club during their re¬ 
cent visit. 
The oldest rocks observed were at 
Chinaman’s Bay. at the south eud of the 
isthmus joining the two portions of Ma¬ 
ria Island. Here a dark-coloured quartz¬ 
ite is exposed not far from the granite. 
It has resulted from the metamorphisni 
by the granite of some sandstone, which 
is older than the igneous rock, and is 
probably, of either silnrian or Ordovician 
age. The unaltered sandstone is obscured 
by surface soil, and it is only near the 
contact: that a clean section of the rock 
is visible, and as all distinguishing marks 
are there destroyed, identification is dif¬ 
ficult. 
The eastern part of the island is formed 
of a portion ot that line of granite which 
extends down the eastern coast of Tas¬ 
mania. As the camp was on the north¬ 
western corner of the island, this rock 
was not examined in detail, but it ap¬ 
pears to be normally of a grey colour, 
pink or dark red in places, it is simple 
in structure, and consists essentially of 
dark biotite. an acid felspar, and quartz. 
In places it is coarse grained with felspar 
crystals two inches long. Near the 
contact with the sedimentables it is finer, 
owing to the more rapid coaling, and as¬ 
sumes a porphyritie appearance with 
phenot r.vsts of felspar and quartz. 
At the north end of the island a fine 
section is exposed at the Fossil Cliffs. 
These consist of permo-carboniferous lime- 
siono ove'lymg glacial conglomerate of 
unknown thickness. This conglomerate 
consists of a matrix of limestone enclos¬ 
ing erratic blocks of various sizes and 
composition. Blocks of granite, quartzite, 
sandstone, slate, and other rocks arc here 
cat het-ul together, both small and large. 
These give the. bed a power of resistance 
to erosion greater than (hat of the over- 
lying limestones, and in consequence it 
projects forward several feet, although 
it is just above sea level, where the force 
of the sea is greatest. The nearest granite 
is some miles away: no river could possi¬ 
bly carry such boulders, which are, more- 
ovr, not water worn, but angular. Ice 
was the transporting agency. 
The beds expo-ed in the cliff are divid¬ 
ed by Mr. li. M. Johnston into the fol¬ 
lowing series:— (v.) Crinoid zone; (iv.) 
prodiielns zone; (iii.) fenestella zone; (ii.) 
pacliydomns zone; (i.) erratic zone. Ex¬ 
amination is considerably helped by the 
fact that large blocks of the upper sc¬ 
ries have been undermined, and fallen 
down to the conglomerate bed. The rock 
is so hard, however, that the. collection of 
specimens is almost impossible, the fos¬ 
sils themselves breaking more readily 
than the enclosing matrix, (i.) This zone 
has been already described. - (ii.) This 
zone forms the lower part of the cliff, and 
so can be easily examined. It contains 
many paehydomus shells, some beds 
being almost entirely composed of them, 
(iii.) The fenestella zone consists of mud¬ 
stones with specimens of fenestella and 
spiriiera. (iv.) These beds have been 
quan led for cement making, and were 
readily reached by camp members. They 
consist of beds of limestone separated by 
calcareous shale and mudstone. Speci¬ 
mens were obtained of fenestella, spirifera 
productus and crinoids. Some fine spe¬ 
cimens of crinoids were seen with wide 
branches, but it was impossible to re¬ 
move them The rock is not: pure, as it 
contains quartz particles. It has evi¬ 
dently suffered from heat or compression, 
as it is highly crystalline. The fossils 
have thus been partly destroyed, but 
there are patches more siliceous than 
the rest, in which multitudinous small 
fossils can be seen closely. In places 
chalcedony has been formed from the 
more siliceous parts. 
In addition to the quartz particles, a 
few water-worn nodules were observed m 
the rock of a dark green igneous rock, sur¬ 
rounded bv an aureole of pyrites. These 
nodules were evidently deposited together 
with the enclosing matrix. From observa¬ 
tion of hand specimens, they appear to 
be the ordinary diabase so common in 
Tasmania. The modem view of this 
rock, however, is that it is of up¬ 
per meso/.oic age, i.e., later than this 
rock. Mr. R, il. Johnston, in his “Geo- 
lo"v of Tasmania,” stated that two erup¬ 
tive peiiods had existed, one of which was 
earlier than these beds. If the rock is 
really diabase, this view would be sup¬ 
ported. but it is so decomposed that iden¬ 
tification would be difficult, even with the 
aid of a miscro.scope. Another view is 
that it might be gnbbro of Devonian age. 
As yet. however, none has been observed 
on the East Coast. As the nodules are 
well water-worn and may have travelled 
some distance, this might be the more 
probable view, but the evidence does not 
warrant an opinion. The aureole of py¬ 
rites round the nodule is interesting, and 
may have been caused by sulphide waters 
permeating the limestone and preoipitat- 
ing nyiltes on coming in contact with the 
iron salts of the igneous rock, (v.) The 
crinoid zone is composed of limestone, 
with plentiful crinoid remains. Overly¬ 
in'.! the limestone sandstone occurs. This 
muv be either of upper pormo-carbonifer- 
ons age or of lower mesozoic, as sandstone 
beds occur in each. Some camp members 
reported that two separate series of sand¬ 
stone occurred, m which case both eras 
might be represented. As the mesozoic 
strata rest conformably upon the permo- 
carboniferous only, detailed work could 
decide whether both arc there or not. In 
either case there is a possibility of coal 
being found, though none was observed. 
Intruded into this series of sedimentary 
