Boggust Park Crater facts for kids
Boggust Park Crater is a volcano located in Auckland, New Zealand. You can find it in the Favona area, which is part of the Mangere suburb. This volcano is one of Auckland city's older ones. Scientists only officially recognised it as a volcano in 2011. The park where it sits is named after Ralph Boggust, who used to be in charge of the Manukau Parks Department.
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What is Boggust Park Crater?
Boggust Park Crater is a special type of volcano called a maar. It has a large, bowl-shaped crater that is about 300 to 400 meters wide. This crater is surrounded on three sides by a low, semi-circular wall. This wall is called a tuff ring. A tuff ring is made from volcanic ash and rock fragments that exploded out of the volcano.
The Tuff Ring's Shape
The tuff ring around Boggust Park Crater is about 6 to 8 meters high. It has steep slopes on the inside, facing the crater. The outside slopes are much gentler. Some parts of the top of this tuff ring were flattened by bulldozers in the 1990s. This happened when the area was being developed for homes.
How the Crater Changed Over Time
The tuff ring has a break on its north-east side. This break was likely made by the sea a very long time ago. About 130,000 years ago, during a warm period between ice ages, the sea level was much higher. It was about 5 to 6 meters above where it is today. The sea probably flowed into the crater through this break.
From Lake to Lagoon to Park
After the volcano erupted, the crater would have filled with fresh water, becoming a lake. When the sea level rose, the sea broke through the tuff ring. This turned the freshwater lake into an intertidal lagoon. An intertidal lagoon is a shallow body of water that is connected to the sea and changes with the tides. It would have been similar to Panmure Basin today.
About 120,000 years ago, the sea level dropped again. The crater then became a swampy area. Later, about 1 meter of soil was added to the crater floor. Drainage systems were also put in place. This transformed the swampy area into the recreational sports field we see today. The bottom of the crater is now about 5 meters above the current high tide level. It slopes down towards the Harania Creek estuary, which leads to the Manukau Harbour.
