THE 
GEOLOGICAL MAGAZINE. 
NEW SERIES. DECADE II. VOL. IV. 
No. XII.— DECEMBER, 1877. 
OBIG-INAL ARTICLES. 
I. On THE OcCURRENCE OF ChALK IN THE New BrITAIN GROUP. 
By Professor Liversidge, Etc., Etc., 
University of Sydney. 
(Eead before the Boyal Society of New South "Wales, July 4, 1877.) 
I N the following brief notice it is my wish to commimicate to the 
Society a description of the physical properties and Chemical 
composition of oue of the geological specimens recently brought 
from the above group of islands. 
The specimen which I now have the honour to lay before you is 
not only interestiug in itself, as an example of what is known as an 
organically formed rock, since it is built up almost entirely of the 
calcareous skeletal remains of organic forms ; but it is interesting 
in a still higher degree, as it apparently indicates that a most impor- 
tant geological discovery has been made of the presence of chalk in 
a hitherto unknown, and even unsuspected, locality. 
In October last, the Rev. G. Brown, Wesleyan missionary, 
brought amongst other specimens from New Britain and New Ire- 
land (New Britain Group, latitude 4° S., and 150° E. longitude) 
certain grotesque figures of men and animals, which had been 
carved by the natives of the above islands out of a soft white some- 
what pulverulent material, having much the appearance of plaster 
of paris or chalk. Some of these figures were deposited in the 
Museum, and a fragment broken off from one of them was placed in 
my hands for identification. 
On examination the remains of numerous Foraminifera are at once 
detected, the forms of the larger ones being plainly visible, even to 
the unaided eye ; under the microscope the whole mass of the rock 
is seen to be almost entirely composed of the shells and fragments 
of shells of Foraminifera, the remains of Globigerince being most 
abundant. To obtaiu the shells of the Foraminifera tree from the 
cementing calcareous matter, it is only necessary to gently rub the 
surface of the specimen with a soft tooth or nail brush under a stream 
of water, when the whole surface of the fragment submitted to the 
Operation speedily becomes studded with the minute shells and frag- 
ments of shells of' Foraminifera, now left standing out in relief. To 
free the Foraminifera perfectly from the accompanying powder, it is 
sufficient to dry the collected debris and to place it upon the surface 
of some clean water contained in a glass beaker or other vessel; the 
larger or more cavernous Foraminifera float on the surface of the water, 
while the broken fragments, much of the amorphous powder, and many 
of the denser Foraminifera, are deposited at the bottom of the vessel 
as a Sediment. The very light and finely divided parts are got rid of 
by decanting the milky supernatant liquid. In the Sediment the 
DECADE n. — YOL. IV. — NO. XII. 34 
