Ōhuiarangi / Pigeon Mountain
Welcome to Pigeon Mountain, the English name comes from the early settlers naming it after numerous the Kereru, New Zealand Pigeons, which were present in the area surrounding the mountain. Ōhuiarangi means "the desire of Rangi and Pakuranga".
Today, the mountain is only half of what it once was, with extensive quarrying taking place in the 1950s-1970s.
Nowadays, the area is a nice recreational reserve with sports fields, a small trail to the peak and a boardwalk following the lava flow to the Tamaki Estuary and the Rotary Track. This is an excellent area for running, cycling and other outdoor activities.
The summit is only around 55 meters above sea level.
Warning:
The trails to the summit are not well maintained, please watch your footing.
Earthcache Logistics:
The area is easily reached by bike, by foot, or by public transit.
Parking on the south and west side, pay attention to signage and gate times.
This cache should only take you a few minutes.
You will need to visit the posted coordinated and answer a few questions.
This Earthcache should not be done at night.
This Earthcache can be fun for all ages.
Mostly, HAVE FUN!!!
---So, let's get to the GEOLOGY.---
(**Terms indicted with a number are defined below**)
Pigeon Mountain around 24,000 years ago with wet explosive eruptions that built a 500-meter wide crater with surrounding tuff1 ring. A scoria2 cone was then built up by fountaining eruptions inside the explosion crater. As the cone formed, a small lava flow poured out from a breach3 on the northwestern side and flowed 700 meters southwest down the valley stopping only when it reached the head of the Wakaaranga Creek.
Additionally a small crater erupted through the tuff ring northwest of the main crater. This smaller crater is only 50 meters across and is the private reserve located in "Heights Park" in Half Moon Bay.
At the peak, you see the remnants of the breached crater with exposed scoria rock. This crater is the best example of the hills volcanic past (as compared to the human-made kumara pits and quarrying). The steep slope on the north side of this crater is due to the removal of scoria. Whereas the south side is composed of kumara pits.
The tuff ring to the north of the center collapsed at one point during eruption, creating an apparent double rim.
In the surrounding neighborhoods, the tuff ring can be seen on private properties and near the foundations of the modern roads and neighborhoods. The best examples of this are along Sunderlands Road.
See images for a photo taken prior to 1940 and an overlay image of the volcano on the modern roads.
Geological Terms Defined:
1) Tuff - A type of rock made from volcanic ash ejected from a vent during a volcanic eruption.
2) Scoria - A cindery, (usually) basaltic lava, typically having a frothy or bubbly texture.
3) Breach - An opening, break or rupture in the bowl shaped crater surrounding a volcanic vent.
Further Learning:
- For more information about Scoria.
- For more information about Tuff.
- For more information about Basalt.
How to log this EarthCache:
(Answered to be sent to my geocaching account, photos can be posted with the log.)
A) At the posted coordinates you'll be standing near the summit.
Q1) Please take a photo of yourself, your GPS, your caching name on a piece of paper or some sort of personal item near the summit, with your favorite view in the background.
(Photo required for logging, so I know you visited the area)
Update - 14 Feb. 2023: The photo is absoluetly REQUIRED to be attached to the log, no exceptions. Do not send the photo to the CO, post it in the log. This photo only need to be proof you visited. It can be as simple as your caching name on a piece of paper. Thank you!
B) Examine the exposed rocks in the crater nearby.
Q2) Describe the nature of the rocks (texture, color, etc.). What types of rocks are these?
Q3) Which direction did the lava flow? Do you see any evidence of the lava flow?
COPY / PASTE QUESTIONS :
For your convenience, you can copy / paste the questions to answer from here:
Required questions for logging -
Q1) Please take a photo of yourself, your GPS, your caching name on a piece of paper or some sort of personal item near the summit, with your favorite view in the background.
Q2) Describe the nature of the rocks (texture, color, etc.). What types of rocks are these?
Q3) Which direction did the lava flow? Do you see any evidence of the lava flow?
Need help?
Are you confused on a question? Rock??? Don't stress! I'm looking for answers that showed me you went to the site and tried.
If there are any problems I will contact you and I am happy to help further or add some information.
If you have any further questions, please feel free to send me a message or look at the following references.
Logging:
Feel free to log this Earthcache immediately.
However, after 10 days, any log that is not accompanied by a message with the answers and a photo will be unceremoniously deleted.
Update - 14 Feb. 2023: The photo is absoluetly REQUIRED to be attached to the log, no exceptions. Do not send the photo to the CO, post it in the log. This photo only need to be proof you visited. It can be as simple as your caching name on a piece of paper. Thank you!
References:
- Volcanoes of Auckland: The Essential Guide. Hayward, B.W., Murdoch, G., Maitland, G.; Auckland University Press, 2011.
- https://en.wikipedia.org/wiki/Pigeon_Mountain_(New_Zealand)
- Volcanoes of Auckland: A Field Guide. Hayward, B.W.; Auckland University Press, 2019, 335 pp. ISBN 0-582-71784-1.
- Pigeon Mountain - The Birth and Death of a Volcano by Geoff Fairfield (1992)