Auckland Volcanoes: Lake pupuke one of the oldest volcanoes of the Auckland field......…..next to the youngest volcano of the region, Rangitoto……
…..next to the youngest volcano of the region Rangitoto……
It probably started with a huge explosion about 120,000 years ago. Basalt coming from depth finally encountered cold water and blasted large volumes of mud and ash into the air where it fell as a tuff ring roughly where hurstmere road skirts Lake Pupuke today. Molten lava swirled round forest trees close to where the Takapuna boat ramp now sits. Trees with their deadly collar of solidifying lava were incinerated and only the moulds remain today . The remaining lava kept on flowing to devastate other parts of the ancient forest.
There are many examples of the effects of lava flowing through a forest containing some very large Kauri trees along the shoreline from the boat ramp to O’Neils Avenue. Places of interest are numbered. Can you spot them in the flickr photos?
- Tree moulds. Swirling lava cooled against trees producing solid blocks about a meter high. The trees incinerated leaving a mould in the centre.
- Looks like brown concrete but actually the remains of the tuff ring. Mud, ash clay and sandstone blasted into the air by the original explosion settled and baked solid with heat and moisture when it settled on the ground.
- Rocks with gas holes (vessicles). Most holes are near the surface
- Blobs of once molten rock that dripped from the roof of a small lava cave. The natural furnace was fuelled by burning charcoal and wood as hot air blew through. Temperatures got high enough to remelt the roof of the cave. A bit like blowing on the embers of barbeque charcoal to get the temperature up.
- Gas holes bubbled around the the wood as it roasted and probably blew apart a hole as it tried to escape from the viscous lava.
120,000 years ago a lava flow streamed through here carrying logs and branches. The wood screamed as it slowly vapourised in the molten lava.