o 
do so) in order that our society may not lan- 
guish and disappear completely, after so patient 
a growth, I purposed to detail “ some of the 
economic uses of the Trappean rocks,” and in 
doing so it would seem a suitable preliminary 
were I to go back to the origin of the rocks in 
question. 
I would observe here that in my endeavour 
io ascertain correctly the true nature of this 
rock, I have felt the want of a geological col- 
lection to which to turn and compare the 
rocks of this district with the figured speci- 
mens of the scientific geologists ; this want, 
taken with my empirical an^ book knowledge 
of this subject, behoves me to crave the indul- 
gence of the society for the errors I am almost 
certain to fall into. May I be permitted to 
express the hope that when the museum, 
which we have in prospective, is begun, a geo- 
logical cabinet may be among the first branches 
that are established ? 
I believe the Trappean Rocks are considered 
as next in order after the granitic series, then 
iollow the volcanic ; in none of which series do 
organic remains occur, hence there is no field 
for the highly important study of palaeontology 
or the science of organic remains among such 
series of rocks. Yet I find for comfort and 
encouragement the following remark in Mr. 
Page’s Text Book in reference to the Trap 
Rocks: — “There is no class of rocks more 
puzzling either to the mineralogist or the 
geologist, their varieties being so numerous 
and their relations to the strata being ofien 
so intricate and decepiire.” However if 
I am not greatly deceived, the masses of 
variegated rock which crop out on both 
sides of the Brisbane River and in various 
parts of the suburbs of Brisbane, are Trappean 
Rocks, and bear the distinctive characteristics 
of clay stone-porphyry. That the rock is por- 
phyritic there is little doubt, by the presence of 
spar-like crystals throughout the various masses, 
and much of it has also the purple colour of por- 
pliyrv ; and that it is a claystone there seems 
little'question, as when breathed upon, it emits 
t lie argillaceous odour peculiar to clayey sub- 
stances, such as pipeclay, &c. This odour is 
frequently perceivable during a shower while 
passing along a road “ metalled ” with this 
stone. When looking at the formation of this 
rock in a quarry, it appears like a closely com- 
pacted mass of the raw starch of commerce. 
It has apparently been originally in the form 
of a thin clay puddle, interspersed with crystals 
o ? felspar and the other components of 
of granite, containing even particles of clay 
slate, which have been held in suspension in the 
fluid or semi-fluid mass, and in this state sub- 
jected to a fervent heat (possibly by water 
raised to an extraordinary temperature, which 
suddenly drove off the moisture, leaving the 
substance slightly vesicular and the crystals 
very generally distributed throughout. The 
process of cooling, which seems to have been 
gradual (for the rock is not hard and crystalline 
like the basalts) has given the columnar struc- 
ture — like starch — which we see in the 
quarries, and the joints are frequently found 
filled with a much harder substance than the 
body of rock and notunlike ironstone, probably 
an aqueous deposition of ferruginous matter. 
It is worthy of remark that clay 
after it has been washed and run into a fine 
puddle, dries into masses much resembling this 
rock in situ, and the raw starch before men- 
tioned. If the foregoing description be the 
correct one of the origin of this trap rock, and 
from the experiment which I am about to re- 
late, I have reason to think it is, there is no 
doubt that we have one of the most useful rocks 
in this and many other districts — for it extends 
to my knowledge, to the Wide Bay Range, at 
least — that the world possesses. 
The experiment I refer to was made 
accidentally by a brickmaker at work near 
one of the quarries beyond York’s 
Hollow, who procured a quantity of the boring3 
from the blastings in the quarry, and converted 
them, being a fine powder, into ordinary bricks 
by the usual processes of tempering and mould- 
ing. The brickmaker assured me that no other 
material was used in their manufacture, except 
the sprinkling of sand it> the mould. I produce 
the bricks made from this material, which I 
consider are evidence that the rock is argilla- 
ceous in its nature. It is necessary to state 
that these bricks are only hand made, not 
pressed. They will prove invaluable 
as the colony gets developed, for 
furnaces, pavements, and very strong 
and permanent buildings, for they are not 
porous, nor are they liable to disintegrate by 
the action of moisture, as the stone in its 
natural state is. And they are certain to be 
fully twice as strong, in consequence of their 
compactness, as the native rock or as ordinary 
brick, although I have no proper means of 
testing this quality in them. Their weight 
is 8*621 lbs. compared (in size) with com- 
mon brick which weighs 7*00 lbs. ; with 
sandstone 10*91 lbs., and with the trap rock 
itself, which weighs 8*82 lbs. Their weight, 
taken into account with their extreme hardness, 
is a fair test of their probable strength to resist 
compression. Some persons may doubt as to 
the possibility of crushing such a hard mate- 
rial, but I need only remind them of the won- 
derful perfection of quartz-crushing machinery 
now ; besides I have little doubt but that a 
very little extra cost on to an ordinary horse- 
puddling machine would be found adequate 
for the thorough pulverisation of this mate- 
rial. 
To enumerate some of the known uses of this 
rock, I would mention its adaptability as a 
building stone, either in its rough or hewn 
shape, its value as a road material, either as 
pavement, channelling or for the purposes of 
macadamising, or for ballasting railway lines ; 
which are frequently ballasted with clay burnt 
for the purpose ; and lastly, its convertibility 
into the bricks already described and shown. 
A similar stone has been used by ancient 
