THE GEOLOGY OF NEW ZEALAND. 
241 
the volcanic. Wherever a volcano has arisen near the sea, or 
in the sea, it has formed sedimentary strata around, in propor¬ 
tion to the quantity of matter ejected. Much of this kind of 
formation is seen at Wangaroa, and Hick’s Bay, where the 
rocks are composed of volcanic grit, and contain most of the 
shells now found on the coast. These deposits are doubtless 
very extensive in a country where volcanic agency has been so 
active. 
Whilst the Geologist marks these strata and the volcanic 
features of the country, he is also struck with the frequent 
upheavements the various localities have undergone. No one 
can walk from Wanganui to Taranaki without observing the 
many alterations of level which have taken place in that district. 
Near the north head of that river he beholds, at low water, the 
stumps of ancient trees still maintaining their position in the 
sea; and on the shore another level appears with numerous 
trees jutting out, which are covered with lofty sand hills. 
Wai Totara,—the river of Totara trees,—takes its name from 
a thick grove still standing in its bed, which so obstructs its 
course that a canoe can hardly wind its way amongst the many 
trunks which rise up in it. At Manawa-pou, where the 
cliffs are little less than four hundred feet high, large stumps 
are also seen standing in the ocean, where they have braved 
for years the force of the violent surf which breaks upon that 
coast. Further on, the cliffs become even yet highei', and 
there also similar remains of forest are seen at the level of the 
ocean, above which is a thick stratum of blue clay, containing 
numerous marine deposits; upon this there is another level 
with large trunks of trees, which are covered with alternate 
strata of gravel, shingle, and sand, then another layer of timber 
is seen, upon which are other deposits, forming the present 
surface of the land. 
By reflecting upon these changes, it is at once perceived 
how many convulsions must have shattered the land, alternately 
elevated it, allowing time for a stately growth of timber, then 
sinking it again into the depths of the ocean, where, year after 
year, age after age, the gradual deposit of mud, finally attains a 
thickness of more than a hundred feet, another convulsion up- 
R 
