PHYSIOGRAPHY OF EASTERN. NEW GUINEA, ETC. ith 
(3) Condition of the craters; 
(4) Causes of activity ; 
(5) Age and future activity. 
(1) Unstable Conditions of the Rabaul Area.—The 
eraters are situated on a very narrow peninsula, with the 
deep waters of St. George’s Channel and Blanche Bay on 
either side. The slope is steep. The eastern slope of Mt. 
Mother drops from a height of about 2,500 ft. directly into 
St. George’s Channe! at its base. The other craters are 
similarly situated. A section line, commencing at Anir 
Island, drawn west and south through New Ireland, Mt. 
Mother, and South New Britain, gives a succession of high 
land and deep water (figs. 3 and 4). Operating in con- 
junetion with these unstable topographic features are the 
periedic very high tides and the strains and stresses due to 
lunisolar earth warping. 
In addition to these local conditions of instability, 
attention may also be drawn to the association of the high 
mountain mass of New Guinea with the great ocean deep 
situated between that island and New Ireland. 
(2) Local Rift System—As might be expected, there 
is evidence of a definite local rift system.. The fumaroles, 
as described in a previous section, have a definite linear 
arrangement in two directions, north-and-south and north- 
east—and—south-west (fig. 2). At the point of intersection 
the activity is considerable. This assumption is supported 
by the fact that in the earlier stages of the last eruption 
great clouds of steam arose along ihe east-west rift-line 
across the deep water of the harbour. All the craters of 
the South Daughter group are arranged about the rift 
system, as well as Mt. Mother, Matunpit, and Vulean Islands 
(fig. 2). Should further eruptions take place, it seems 
likely that a new erater will be formed at the intersection 
of the rift-lines. There, as previously stated, quite a 
number of fumaroles occur in close conjunction, forming a 
natural outlet for any further explosive activity. 
(3) Condition of the Craters—lt is unfortunate that 
the craters are plugged, for it is impossible to observe their 
internal condition. Certain facts maz’, however, be deduced. 
The floor of the old South Daughter Crater rings very 
hollow and may be comparatively thin, covering a deep aid 
R.S.—H 
