Perhaps the most distinctive geographical character of the New Zealand archipelago is its coastline.

From low and sandy in the far north, the coast goes on to display a great diversity of shapes, rock types and vegetation, with jagged rocky cliffs, mudflat-lined harbours, large volcanic cones or their remains and black sand beaches but to name a few, finally to rise abruptly from the sea straight up to the lofty ice-covered summits of Fiordland.

This diversity is the product of a geological history that spread hills or mountains over much of the islands' area, thus explaining why only a fraction of the shoreline rises gently out of the sea and into lowland plains.

Sharing the coast's geological background these hills and mountains also show considerable diversity, from the monolithic uplifted blocks north of Auckland, to the similarly low altitude but intricately dissected river valleys of central North Island, to the long, narrow and fairly high rocky backbone of eastern North Island, finally to the Southern Alps and their own diverse range of rock types and landscapes.

Such a dynamic relief is the sign of recent and on-going mountain building. The southern Alps are geologically very young and still rising fast, although the rate of erosion, helped by the west coast's exceptionally high precipitation, keeps it in check. An even more obvious sign of recent and current mountain-building is given by the North Island's great volcanoes. While these are still active, older and sometimes highly eroded remnants of past volcanic activity are found throughout the archipelago, from Port Chalmers and Banff Peninsula in the south to Mt Pirongia, the Coromandel Peninsula and all the way to the Three Kings Islands in the far north.

A common feature of all these mountains is their origin in the forces unleashed by plate tectonics. The New Zealand islands stretch along the line of contact between the Pacific plate and the Australian plate. These plates' movement relative to each other is switched in a spectacular way by the Alpine Fault, but in all cases it is the direct cause of volcanism, mountain building and the tectonic activity that produces earthquakes. While the impact of the first two in the landscape is usually obvious, lakes formed, like Lake Waikaremoana, after streams were cut and dammed by landslides may be the clearest legacy of earthquakes in the landscape.