382
Accessibility: WHEELCHAIR ACCESS
WHAT'S HERE?
Looking down Northcote Rd, 2009. Cutting is on right side of road. Photo Bruce Hayward.
Exposes sequence of eruption of Pupuke Volcano from dry lava flow and scoria eruptions to later wet explosive ash and base surge eruptions. Unique sequence in Auckland Volcanic Field.
Best example of rafted scoria knoll in Auckland.
Loose olivine crystals in some scoria layers.
Best example of rafted scoria knoll in Auckland.
Loose olivine crystals in some scoria layers.
LEARN ABOUT IT
Flooded quarry arm and Northcote Rd where cutting is located, 2009. Photo Bruce Hayward.
This Northcote Rd road cutting exposes part of the rock sequence produced by the eruption of Pupuke Volcano. Pupuke Volcano is one of the oldest known volcanoes in the Auckland Volcanic Field, along with Onepoto at Northcote (and probably Tank Farm in between them).
Pupuke Volcano is unique in the Auckland Volcanic Field because it erupted first in a dry style and later switched to wet (phreatomagmatic) eruption style. All others did the reverse. The oldest rocks along the end of Northcote Rd are basalt lava flows that underlie the rocks in the lower half of the road cutting. The basalt lava can be seen along the edge of the flooded arm (old quarry) on the other side of the road and also in the lower part of Smales disused Quarry at the top of the section and in the upper half of the road cutting section. In the upper road cutting several flows can be distinguished separated by an irregular layer of scoriaceous breccia.
The lower part of the road cutting exposes layered tuff (ash) that was erupted by wet explosive eruption blasts from the Pupuke crater. In one place a 5 m high steep-sided knoll of scoria is buried by later layers of tuff. This appears to be part of a scoria cone that was rafted away from the cone on top of the lava flow and soon afterwards buried by the volcanic ash.
Pupuke Volcano is unique in the Auckland Volcanic Field because it erupted first in a dry style and later switched to wet (phreatomagmatic) eruption style. All others did the reverse. The oldest rocks along the end of Northcote Rd are basalt lava flows that underlie the rocks in the lower half of the road cutting. The basalt lava can be seen along the edge of the flooded arm (old quarry) on the other side of the road and also in the lower part of Smales disused Quarry at the top of the section and in the upper half of the road cutting section. In the upper road cutting several flows can be distinguished separated by an irregular layer of scoriaceous breccia.
The lower part of the road cutting exposes layered tuff (ash) that was erupted by wet explosive eruption blasts from the Pupuke crater. In one place a 5 m high steep-sided knoll of scoria is buried by later layers of tuff. This appears to be part of a scoria cone that was rafted away from the cone on top of the lava flow and soon afterwards buried by the volcanic ash.
HAVE A LOOK!
The two craters of Pupuke Volcano. Photo Bruce Hayward, 2009.
Can you find the steep-sided knoll of scoria buried by the tuff? Where do you think the scoria cone once was?
See if you can see the hard basalt lava flows in the two old quarries.
How do you think they managed to quarry the lava from the arm that is now flooded by the lake?
Why do you think Pupuke Volcano switched from dry to wet eruptions part way through its history? Could it maybe have something to do with the Wairau Stream?
Pupuke Volcano has two recognisable craters joined together - look at a map and see if you can recognise them?
The level of Lake Pupuke water was lowered by at least 4 m during the 1930s-1940s as a result of extraction of water for Devonport, Northcote and Birkenhead boroughs. What would the lake have looked like then?
See if you can see the hard basalt lava flows in the two old quarries.
How do you think they managed to quarry the lava from the arm that is now flooded by the lake?
Why do you think Pupuke Volcano switched from dry to wet eruptions part way through its history? Could it maybe have something to do with the Wairau Stream?
Pupuke Volcano has two recognisable craters joined together - look at a map and see if you can recognise them?
The level of Lake Pupuke water was lowered by at least 4 m during the 1930s-1940s as a result of extraction of water for Devonport, Northcote and Birkenhead boroughs. What would the lake have looked like then?
-36.7835210549784
174.758893847466
Directions/Advisory
Proceed north towards the lake on Northcote Rd from Taharoto Rd lights. Do not follow the main drag to the left towards North Shore Hospital but proceed straight ahead on the smaller road and park somewhere down there towards the lake edge and the rowing clubhouse.
Keep a watch out for cars on this dead end road. Wear a reflective jacket for higher visibility. If you cannot swim do not risk falling into the arm of the lake alongside the road as it is deep (old flooded quarry).
Google Directions
Accessibility:
WHEELCHAIR
View the roadcutting on the right (east side) of Northcote Rd between Smales Quarry (deep hole on right) and the carpark at the end of the road beside Lake Pupuke. All on sealed road.
Features
Volcanic
Landform
Geological Age
Pupuke erupted about 200,000 years ago. Middle Pleistocene
Zealandia Evolution Sequence
Pākihi Supergoup: 5 million years ago – present
Links