316 JEssays. 



accompanying shales, deposited unconformably. At the period of deposi- 

 tion of the coal we must have had dry land for the groAvth 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 eai-th 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. Yarious 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 Eangitikei Eiver, 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 apjoears to have formed a 

 series of terraces, gradually rising to the volcanic plateau and chain, and to 

 the palaeozoic ridges ; but, whether from contraction, or from the shaking of 

 earthquakes, or from imequal 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 remarkr 

 able character. 



GrENEEAL ViEW IN PASSIITG BOUND 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 



* TerehratulcB are found in gravel at Cape Palliser 200 feet above the sea level, and' 

 a long rest of the sea level at a lovi'er elevation may be inferred from the growth of pohu- 

 tukawa trees in certain inland districts of the Auckland Province, a tree which only grows 

 naturally on the sea shore.— Thomson, pp. 1, 10, and 12. 



