GEOLOGY
The Auckland Domain is built on the rim of one of the city's oldest volcanoes - Pukekawa, that erupted 100,000 to 150,000 years ago. Pukekawa came to life with a large explosion or series of explosions and evidence of those can still be found in the domain.
The volcano's name means "hill of bitter memories", referring to Maori tribal battles fought there until 1828 between Hongi Hika leading the Ngapuhi from the North and Potatau Te Wherowhere leading the local Ngati Whatua.
The bank surrounding the playing field with the Auckland War Memorial Museum on one side and the hospital on the other is a tuff ring surrounding the explosion crater, made of a mixture of fine scoria, or lapilli, and original basement rock. There is also a small lava flow to the west of the tuff ring, as well as a small scoria cone formed by fire fontainning in the centre.
The crater floor was initially a lake. Thousands of years saw it filling with alluvium and plant remains to become a swamp. Later in European times, the swamp was eventually drained and smoothed to become playing fields.
The duck ponds in the domain are in fact fresh water springs derived from ground water draining the Crater lake and swamp. Those springs provided the city's first piped water supply in 1866.
The Wintergarden's fernery is located on top of a disused scoria quarry on the North side of the small central scoria cone.
EARTHCACHE
In order to log this Earthcache, you must complete a short walk around Pukekawa and, for each location mentioned below, perform certain specified tasks. Answers to questions should be emailed to the cache owner and the requested photo should be uploaded with your online log.
Crater: Between and behind the buildings at this location there is some volcanic rock exposed which can be examined. What type of lava is this known as? Describe the predominant colour(s) and texture.
Quarry: The fernery in the Wintergarden is a disused quarry. This waypoint is only available between 9am and 4:30pm (Winter), 5:30pm (Summer) or 7:30pm (Summer Sunday). What type of rock was quarried here? You may notice that the ponds in the fernery are lined with concrete instead of the locally quarried rock - why do you think that is?
Duck Ponds: These ponds are natural freshwater springs and provided Auckland City with its first piped water source. Please take a photo of the ponds, including your GPSr clearly in the photo.
Stream: This stream is the outflow from the duck ponds. The shaped basalt blocks in the stream bed are not from this volcano but another in the region. Who do you think put the blocks there and for what purpose?
Tuff Deposits: Here you will find an exposed section of tuff deposits. Describe the exposed tuff you can see in terms of colours and texture.
You can log this cache straight away after you have emailed your answers to the cache owner, no need to wait for confirmation. Please include the name of this earthcache in the email - you'd be surprised how many people forget. Also, when contacting us with answers, if you want a reply, please include your email address. Any problems with your answers we'll be in touch.
HAPPY EARTHCACHING!!!
kiwicouple