Auckland’s geology: What’s lies beneath
Today, Auckland is known as the City of Sails and is the biggest city in the country. It’s filled with exciting new attractions and is constantly changing, but underneath it all, the geology of the city and its surrounds are just as fascinating.
A volcanic history
Much of Auckland’s geography all comes down to volcanoes. In fact, within a 20 kilometre radius of the city centre, there are as many as 49 volcanoes.
Many of these still feature as major landmarks around the city today. For example, Mt Eden just outside of the CBD is the highest of them all at 196 metres, and you can now visit this lush green parkland and walk or bike to the top for an incredible view of Auckland.
Another of the most famous volcanoes is Mt Rangitoto, which sits just offshore and is the most recent of Auckland’s volcanoes, having erupted just 600 years ago. If you make it out for a trip to this fantastic island, you can find more than 200 species of native plants and trees.
Even the popular Auckland Domain is the site of an old volcano. It’s where you’ll find the Auckland Museum and many of the city’s big outdoor events, but it’s also where a volcano erupted more than 100,000 years ago (making it one of the city’s oldest).
If you look even further back in time, you’ll see that the city’s volcanic history isn’t just confined to a relatively recent era. In fact, the Waitakere Ranges – where we do many of our day tours from Auckland – were formed sometime between 15 and 22 million years ago in the Miocene period. Back then, everything that is now Auckland was still under the sea, up until massive forces pushed the Waitakere volcano up above sea level.
By comparison, most of Auckland’s volcanoes are quite small compared to others around the globe. Even those that still pose a small risk of explosion would only affect a 5-kilometre radius. While this would still cause huge disruptions to the city, this is still a much smaller area than could be expected in other places. Fortunately, experts expect they would be able to give days or weeks of warning for people in the area.
Rocks and minerals
Auckland, like much of New Zealand, is high in greywacke – a hard type of sandstone. You can see some of this material in Auckland’s east in the Hunua Ranges.
Over time, this greywacke became part of the ‘basement rock’ of the Auckland region, and were joined by new sediments from millennia of volcanic activity. With the help of erosion, the Auckland of today was formed. Some of the best places to see the rocks beneath Auckland are around coastal areas where you can see the layers in cliff faces that exposes years and years of history and geology.
Auckland is without doubt an incredibly historic and fascinating place, and you can learn a lot more about its natural flora and fauna during a Habitat Tours day trip from the city.
Tristan Cullen - Passionate Conservationist