316 Essays. 
accompanying shales, deposited unconformably. At the period of deposi- 
tion of the coal we must have had dry land for the growth of coal plants. 
After the deposition of the coal, the island must have undergone depression, 
and, as it sunk, the various tertiaries must have been deposited above the 
coal. Not yet, perhaps, did the volcanic eruptions commence ; but as the 
country gradually sunk, and reached its point of greatest depression, the 
crust of the earth was broken, and streams of basalt flowed over the surface, 
` the depression probably reaching a depth of 1,800 or 2,000 feet. Nature 
having completed her work so far, the island commenced to rise again slowly 
and steadily, but slightly disarranging the tertiary rocks on either side of 
the island, the volcanic eruptions doubtless still continuing. The island 
appears to have rested in its rise at various points, at from 1,000 feet to 
1,200, at 400, 150 to 200, at 15, and at 9 and 4 feet. Various comparatively 
slight oscillations of level appear to have taken place in recent times, for we 
find strata of trees, not yet converted into lignite, covered by marine 
deposits—as between Whanganui and Taranaki, on the Rangitikei River, in 
Palliser Bay, and in places in the Auckland Province.* 
Thus, after a depression of 1,800 or 2,000 feet, and the deposition of 
successive beds of tertiary strata, the island rose again, and assumed some- 
what of its present form, although probably at the time of emergence it was 
joined to the South Island. 
I must not omit a most striking feature of the tertiaries in the southern 
part of the island, in the very broken character which they assume over 
large areas, notwithstanding their general horizontality. The great tertiary 
basin in the interior of the West Coast country appears to have formed a 
series of terraces, gradually rising to the volcanic plateau and chain, and to 
the palzozoic ridges ; but, whether from contraction, or from the shaking of 
earthquakes, or from unequal rising of the land, or simply from the wearing 
away of soft rocks by the action of rain and rivers, each, several, or all of 
these causes have cut up the terraces into deep ravines of a very remark- 
able character. 
GENERAL VIEW IN PASSING ROUND THE Coast. 
To give a general idea of the character of the New Zealand landscape, as 
chiefly affected by its geological formations, it will be desirable to travel, 
round the coasts of the North Island. 
On approaching New Zealand from the westward, it is possible that the 
* Terebratule are found in gravel at Cape Palliser 200 feet above the sea level, and 
a long rest of the sea level at a lower elevation may be inferred from the growth of pohu- 
tukawa trees in certain inland distriets of the Auckland Provin. ce, a tree which only grows 
naturally on the sea shore.—Thomson, pp. 1, 10, and 12. 
