PHYSIOGRAPHY OF EASTERN NEW GUINEA, ETC. 95 
shock approached. To those standing m the open, the 
eround seemed to roll in definite waves, which seemed to 
be travelling from the south-east—that is, from the direction 
of the craters. The bungalows rocked violently and 
threatened to fall frem their foundations. Trees shook 
violently and posts of different kinds moved visibly. 
Considerable damage was done to glassware and furniture. 
As far as could be judged without instruments, the 
shocks seemed to be travelling from the direction oi the 
South Daughter craters. Fortunately, the intensity was 
not great though the amplitude seemed to be considecable. 
As no information is available as tc the behaviour of the 
craters and fumaroles, and the intericr condition being 
unknown, it 1s quite impossible to eerrelate tis class of 
shock with any definite crateral coridijion, thorgh all the 
evidence points to the craters as the seat of origin. 
(3) Quite distinct from the former classes of shock 
are the frequent tremors and microtremors, most of which 
are not felt. The area seems to be in a state of continuous 
movement. The influence of these tremors, even when not 
felt, may be observed in any of the wells in the town ot 
Rabaul. The water is in a continuously rippled condition. 
V.—CONCLUSIONS. 
It is proposed to discuss the evidence outlined in the 
previous sections under two heads—(i) the voleanic 
system, (11) the general physiography of the area. 
(1) THe Voucanic System.—The ultimate origin of 
the Rabaul voleanic system is probably to be found in the 
creat stress movements, to be deseribed later, which folded 
and faulted the whole marginal area of the old continental 
mass that included Australia, New Guinea, and surrounding 
islands—Solomons, Hebrides, Fiji, Tenga, Kermadec, and 
New Zealand, and probably the East Indies. The volcanic 
systems of New Guinea and New Britain undoubtedly lie 
along zones of fracture caused by the earth movements. 
In this section, however, only the purely local conditions 
of the Rabaul voleanie system will be considered. 
The following subjects will be dealt with :— 
(1) The unstable conditions of the area; 
(2) Loeal rift system ; 
