Professor Cotton has aptly described New Zealand ' as a concourse of earth-blocks of varying size and shape.' These earth-blocks were raised during this period of mountain-building. The edges of each block were defined by great faults— or lines of fracture in the earth's crust—along which movement took place, some blocks rising to great heights, while others were pressed down or failed to rise. The highest blocks form the -mountainous back-bone, so typical of New Zealand, and, generally speaking, the present coastal areas and foothills are the marginal low-lying page 17

Diagrams showing how land features were formed in the Kaikoura period of mountain-building. A. The covering strata shield the 'undermass' but are worn down by erosion. B. The wearing-away of the covering strata has produced the typical land-surface of to-day. W. N. Benson

The Kaikoura Mountains from Island Bay, Wellington. On the left are the Seaward Kaikouras, in the centre is Mount Tapuaenuku (9,465 feet), the highest peak of the Inland Kaikouras. Government Tourist

blocks. Perhaps the most spectacular movements of this period were those which brought the Kai-koura Mountains into existence, for in their formation upward movements of 10,000 feet occurred. The structure of the blocks is two-fold. First there is an 'undermass' of rocks formed by the sediments of Mesozoic times, but now folded and altered. Above this lie horizontal beds of Upper Cretaceous and Tertiary age, these forming the 'covering strata.' The subsequent geological history of New Zealand is the story of the wearing down of this concourse of earth blocks by agents of erosion. Rain, running water, and wind have played their part. Changes in temperature and the freezing of water have also assisted in wearing down the rocks. But perhaps the most remarkable changes were brought about by the action of moving ice during New Zealand's great Ice Age.