ANNIVERSARY ADDRESS. 17 
and each having a thickness of from thirteen to twenty feet. The 
phase of the eruption then changed, and volcanic dusts alone were 
_ outpoured. These were blown high into the air, so that when they 
settled down they covered a considerable area with a layer of red 
tuff twenty feet deep. In the next phase of the same eruption, 
or at the commencement of a second eruption, which must have 
succeeded the first after only a short interval of time, sheets of 
lava having a total thickness of two hundred and sixty feet rolled 
down and completely buried the first bed of red tuffs. It is in 
this massive sheet of basalt that the Kiama Blowhole is situated. 
A second bed of red tuff was then formed having a thickness of 
from one hundred to two hundred feet. This bed can be traced 
from the Cambewarra Range, above Nowra, on the south, to a 
mile beyond Wollongong on. the north, a distance of about fifty 
miles ; and these two points are by no means the extreme limits 
of the tuff bed. The eruption, therefore, which produced it was 
probably on a far grander scale than the celebrated eruption of 
Tarawera, in New Zealand, in 1886. 
Evidence collected last year points clearly to the fact that all 
the above described members of the volcanic series were erupted 
before the formation of any portion of the Bulli coal-measures, 
There followed an immense outflow of lava, which formed the 
thickest sheet as yet known in New South Wales, its thickness. 
being about six hundred feet. This lava (an andesitic dolerite), 
appears to have been also older than the Bulli coal-measures. 
The relation of the still newer lavas above the andesitic dolerite 
to the Bulli coal-measures has not yet been worked out; but the 
evidence proves that after the Bulli coal-measures had formed 
above the volcanic series, both coal-measures and lavas were inter- 
_sected by doleritic dykes, which have either coked or destroyed 
large areas of coal in the Illawarra coal-field. 
At a still later period, the Illawarra coal-field was further 
disrupted and intersected by a newer set of dykes, some of which, 
as pointed out by Mr. Evans, the manager of the Bulli Coal Mine, 
have cut their way completely through the older dykes. Micro- 
B—May 3, 1893. 
