846 Transactions.— Geology. 
known as the trap series, largely distributed over the earth's surface, and 
as they contribute in a larger degree than any other class of rocks to the 
economy of vegetable and animal life, I may be exeused in alluding here 
to their properties in this respect. In their composition they contain in 
considerable quantity potash and other salts necessary to the growth of 
plant life, and when decomposed by the sun’s heat and rain, which destroy 
their cohesion, the pulverized particles are washed down into the valleys 
and form our best soils for growing grass and cereals. It is possibly one 
of the best tests in looking after new country for settlement, to examine the 
character of the rocks surrounding the country you are traversing, and you 
may rest assured that if this trap series is the prevailing rock the valleys will 
be rich and fertile. We have a very good example of this in that part of 
our township called The Wood, where we have that rich sedimentary deposit, 
where we grow hops and vegetables. That district has at some former period 
been a lagoon of comparatively still water, the force of the Maitai current 
being broken by the bluff at Mr. Huddleston’s property, and the sediment 
from the degraded trap dykes I have before mentioned, finding its way in 
solution into this lagoon, gradually deposited itself into a rich alluvium, 
which proves so fertile for cereal crops. I conclude, therefore, that this 
alluvium is chiefly a decayed trap deposit, because no other rock in the 
Maitai series from its composition could give out soil of this description. 
The dyke from which this deposit has chiefly come runs from Mr. Huddle- 
ston’s Bluff, past the back of Mr. Sharp's house, and again shows itself on . 
Mr. Curtis’s property, on the Wakapuaka Road, the worn-down face of 
this ridge being the deposit I have now mentioned. 
robably our greatest misfortune in the Province of Nelson is, that we 
have so little of this class of rock, but are surrounded on all sides right on 
to the west coast by slates, schists, and rocks of a quartzose character, and on 
the east by the Dun Mountain Range, by slates and a variety of rocks of a 
magnesian class, extending from D’Urville Island in the north, to the Top- 
house at the head of the Wairau Valley—all these rocks I have mentioned 
being from their composition unfavourable to plant life, and the alluvium 
from them being considered country of a third or fourth class. We are 
not, however, left without some comfort in having at different points in our 
surroundings rocks of a more fertile class, such as a voleanic trap, granites, 
and limestones of various kinds, and some others containing felspar in con- 
siderable quantity, which has given the district some rich alluvial soil. We 
are very apt, in travelling through a country, to pass along giving very little 
heed to the character of the rocks surrounding us on every side, but there 
is little doubt that the fertility or non-fertility of a country depends very 
much on the character of the rocks by which it is intersected. 
