Notes

Contents: Out of the ocean -- 1. Introduction to geological terms and concepts -- 2. The oldest rocks (300-110 Myr ago) -- 3. Coal, limestone and karst (Te Kuiti Group, 40-25 Myr ago) -- 4. Northland's displaced rocks (100-22 Myr ago) -- 5. Early Miocene sedimentary basins (23-17 Myr ago) -- Into the fire -- 6. Northland Volcanic Arc (24-15 Myr ago) -- 7. Coromandel Volcanic Zone (18-2 Myr ago) -- 8. Eroding down the land (15-4 Myr ago) -- 9. Intra-plate basalt volcanic fields (last 10 Myr) -- 10. Block faulting, old rivers and volcanic ash (last 5 Myr) -- 11. Crafting the coast (last 2.6 Myr) -- 12. Moulding the land -- 13. Local map guides to features of interest.
Summary: For decades teachers, biologists, geographers and interested members of the public have asked for an up-to-date account of how Northland, Auckland and the Coromandel Peninsula and their landforms were formed. Here, for the first time, is an accessible account designed to be of interest to all levels of understanding. Almost all of the older rocks were deposited as sediment or erupted as lava on the floor of the ancient Pacific Ocean. Some were plastered onto the coastal edge of Gondwana, and at least 100,000 km3 of these rocks were pushed up out of the ocean and slid onto Northland, about 20 million years ago. About the same time, 1 km-thickness of Waitemata sandstones were deposited in a deep-sea basin over Auckland. Most of the subsequent history of northern New Zealand was dominated by fiery volcanic activity of greater diversity than any area of similar size elsewhere in the world. This included eruptions of andesite stratovolcanoes, giant caldera volcanoes, searing ignimbrite flows, viscous rhyolite domes and at least 200 small basalt volcanoes erupted in seven volcanic fields. The present-day shape and landforms of the region reflect its more recent history with local uplift, erosion, volcanic activity, construction of New Zealand's largest sand-dune barriers and harbours, and moulding of the coast by the oscillating sea levels during the Ice Ages. (Publisher)
Geoscience Society of New Zealand miscellaneous publication ;
146.