Park. — Birth and Development of New Zealand. 73 



Art. IX. — The Birth and Development of New Zealand. 

 By Professor James Park, F.G.S., F.N. Z.Inst. 



[Read before the New Zealand Science Congress, Palmerston North, 26th January, 1921 ; 

 received by Editor, 2nd February, 1921 ; issued separately, 27th June, 1921.] 



Though it contains in its fabric rocks of great antiquity, considered as a 

 geographical unit New Zealand is, geologically speaking, very young. We 

 must ever bear in mind that, though it may be built of stones of great 

 antiquity, a house is not older than its builder. And so it is with New 

 Zealand. Its framework is composed of an extraordinary pile of Palaeozoic 

 and Mesozoic rocks, but it was not till the Cretaceous epoch that these 

 rocks were built up into the mountain-chains and other land-forms 

 familiarly known to us by the geographical name " New Zealand." 



The Palaeozoic sediments were derived from the denudation of a land 

 area that formerly occupied the greater part of the Southern Hemisphere. 

 This anfcient continent certainly existed throughout the whole of the 

 Palaeozoic era, and eventually became submerged some time in the Meso- 

 zoic. Like the larger continents of the present day, this Archaean land 

 was dominated by mountain-chains, tablelands, and plains, and its coasts 

 were deeply indented with bays and estuaries. Though no trace of this 

 Pacific continent now remains, the pile of sediments derived from the 

 wear-and-tear of its surface tells us that it was no arid land, but possessed 

 an abundant rainfall. Moreover, there is evidence that in the Cambrian, 

 Devonian, and Permian epochs its alpine chains were covered with an ice 

 cap from which tongues of ice reached down the mountain-glens towards 

 the sea. 



The great rivers which drained the highlands built up mighty deltas 

 along the ancient strands, covering the floor of the seas where New Zealand 

 now stands with sands and muds many thousand feet in thickness. But 

 we must not assume that deposition was continuous in the New Zealand 

 area throughout the whole of the Palaeozoic. No rocks of Devonian or 

 Carboniferous age are known in New Zealand, and from this we infer that 

 during a great hiatus, the exact limits of which are not yet definitely 

 ascartained, there was a cessation of deposition on the floor of the seas 

 covering the area now contained within our borders. The cessation of 

 deposition on a sea-floor may arise from the profound submergence of the 

 land area providing the sediments, or from the uplift of the sea-floor as a 

 consequence of crustal folding or a recession of the sea. By submergence 

 the scene of deposition is shifted landward, and by uplift seaward. The 

 absence of Devonian and Carboniferous rocks leaves a tremendous gap 

 in the geological history of New Zealand, and is ascribed to crustal folding 

 that raised the sea-floor, thereby enlarging the borders of the ancient 

 Palaeozoic continent. 



In the late Carboniferous there began a general transgression of the sea 

 that submerged the coastal lands and permitted the deposition of the 

 Permo-Carboniferous Maitai series on the folded rocks of the Silurian and 



