Following the Hokonui diastro phism a series of sediments ranging from Middle Cretaceous to Upper Pliocene was deposited, but the record has received diverse interpretations, particularly in regard to the structural relations of the beds and the correlation of formations in neighbouring regions. According to the view of Marshall, the whole series is conformable throughout, a difference in age of the basal strata in different districts being ascribed to overlap over an irregular surface of the older rocks. Summarily, the sequence of forma tions is as follows: The oldest rocks of this sequence are developed in the Kar koura mountains of Marlborough, where a thickness of from 3,00o to 9,00o ft. of sandstones and mudstones, with conglomer ates and some coal measures were deposited. These Albian beds are followed by the Amuri limestones (2,500 ft.), but in Canter bury and the coast of Marlborough Senonian strata underlie the limestone series. In the succeeding Eocene period the coal measures of the south-western district of the South island were formed and constitute the most valuable coal seams of New Zealand. The transgressions of Oligocene and Miocene times submerged much of both South and North islands, but in the central region of Otago the land remained emergent. Fluviatile and lacustrine deposits, however, covered large parts of this area. They are frequently auriferous. A general retreat of the sea from the South island took place in Pliocene times, but the North island remained largely below sea-level. In the Wanganui area a wonderful development of clays, 3,500 ft. thick, was de posited, apparently without break. The present topography of New Zealand developed as a result of important crust warpings and block faulting. The faults are not simple tensional move ments, but involved strong lateral pressure, in which overthrusting and overfolding are developed. The isoclinally folded Tertiary rocks of the Lake Wakatipu region show particularly well the extreme effects of this movement. The earliest development of vulcanicity after the Post-Hokonui orogeny is seen in the Middle Cretaceous basalts of the Clarence region and the Upper Cre taceous rhyolites near Christchurch. Vulcanicity became more widespread in Mid-Tertiary times. To this period belong the pillow lavas and tuffs of the Oamaru district and the rhyolites, andesites and dacites of the Coromandel peninsula. Propylitization of these andesitic rocks gave rise to the auriferous deposits of this latter area. Somewhat later came the alkaline eruptions of the Dunedin district and the basalts forming Banks peninsula. The alkaline rocks of the former area include a varied succession of alkaline trachytes, phonolites, trachydolerites and basalts.
Volcanic activity of Upper Tertiary time extending to the present day led to extensive eruptions of andesites and rhyolites in the North island. Mt. Egmont consists largely of andesite. The main centres of activity lie on a north-east line of crustal weakness extending from Ruapehu to Mt. Edgecumbe, and the great rift of the Tarawera eruption extending to Lake Rotomahana has a similar trend. In the Pleistocene, the present system of glaciers had a great extension, and they undoubtedly reached sea-level in the south-west of the South island. On the east they appear to have been confined to the mountain valleys.
Study of the fossil fauna and flora of the New Zealand region points from many lines of evidence to intimate connection, in Mesozoic times, between this land, Australia and Malaysia. In
the later Cretaceous period the connection between Australia and New Zealand was severed, though the latter was directly associated with Antarctica. In the Upper Cretaceous only one species of mollusc (Natica variabilis) is known to be common to Australia and New Zealant:. The complete isolation of the New Zealand region seems to have been accomplished by Middle Ter tiary time, by a gradual break up of the circum-Pacific con nections.
In Jan. 1840 there may have been 2,000 whites in New Zealand. By 1861 the number was still slightly under 100,000. During the next 20 years the gold discoveries, the public works expenditure, and the development of agriculture, multiplied the number of colonists five times to 498,00o in April 1881. Then increase slackened for many years, and was slowest between 1886 and 1891, when the addition was but 48,000 in five years. In 1901 the whites numbered 773,000; and between that year and the census computation in April 1906 the increase, 115,859. In 19" the white people had increased to 1,008,468, and in 1916 to 1,099,449. The census figures for 1916, 1921, 1926 and the estimated population at March 31, 1931, were as follows :— *Prior to the census of 1926 half-castes living as Europeans were counted as Europeans. (All half-castes are now classed with Maoris.) The gain in population in the two last census periods was : from 1916-21, 119,464 or 10.87%, and from 1921 to 1926, 129,792 or 10.69% (the last figure, of course, excludes half-castes). The average annual increment of population is less than 21%. The number of males in 1926 was 686,384, and females 658,085. The number of females to 1,000 males has risen from 622 in 1861 to 959 in 1926.
In 1916 the birth rate per 1,00o was 25.94 and in 1926, 21.05. In the same periods the death rates per i,000 were 9.64 and
respectively. The population is chiefly centred in the North island and the drift that way, largely due to the development of the dairy industry, is growing. In 1926, 61.87% of the people resided in the North island. The Maoris, who are not included in this percentage reside chiefly in the North island. The census statistics of 1926 classed 51.62% of the population as urban. The total population of North island in 1926 was 831,738; the total population of South island (including Stewart island and Chatham islands) was 512,636. Of the entire population, 559,068 lived in the rural districts and 785,316 in boroughs.
In 1921, 98.43% of the inhabitants (exclusive of Maoris) had been born in the British empire. Of the total in 1921, 74.39% were born in New Zealand, 19.54% in the United Kingdom, and 3.94% in Australia. A certain number of those born in foreign countries were of British parentage or nationality, and including these the proportion owning British nationality, in 1926, was 99.35%.
The number of aliens steadily diminished—from 12,050 in 1911 to 7,901 in 1921. Certain restrictions are placed upon the entry into the dominion of "race aliens," a classification implying persons of other than Europeans. Of the total population in 1925, 43.66% were members of the Church of England, 25.42% Presbyterian, 13.93% Roman Catholics, and 9.53% Methodists.