Onepoto (volcanic crater)
Encyclopedia
Onepoto is the name of a volcanic explosion crater (or maar
Maar
A maar is a broad, low-relief volcanic crater that is caused by a phreatomagmatic eruption, an explosion caused by groundwater coming into contact with hot lava or magma. A maar characteristically fills with water to form a relatively shallow crater lake. The name comes from the local Moselle...
) in North Shore City, New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
. It is a part of the Auckland volcanic field
Auckland Volcanic Field
The Auckland volcanic field is a monogenetic volcanic field in the North Island of New Zealand. Basaltic in nature, it underlies much of the metropolitan area of Auckland....
.
Located near the approaches to the Auckland Harbour Bridge
Auckland Harbour Bridge
The Auckland Harbour Bridge is an eight-lane box truss motorway bridge over the Waitemata Harbour, joining St Marys Bay in Auckland with Northcote in North Shore City, New Zealand. The bridge is part of State Highway 1 and the Auckland Northern Motorway...
, it was created by a series of eruptions approximately 250,000 years ago. The crater first became a freshwater lake, and later became a tidal lagoon
Lagoon
A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...
when sea level rose to the present level 7000 yrs ago after the last ice age
Ice age
An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...
. The crater's floor has been reclaimed
Land reclamation
Land reclamation, usually known as reclamation, is the process to create new land from sea or riverbeds. The land reclaimed is known as reclamation ground or landfill.- Habitation :...
, with recreational sports fields and a pond, and some parts of the tuff ring were quarried away in the 1950s to provide fill for the Northern Motorway
Auckland Northern Motorway
The Auckland Northern Motorway is a major motorway in the Auckland Region of New Zealand, linking central Auckland City and Puhoi in the Rodney District, via the Hibiscus Coast and North Shore...
.
See also
- Onepoto BridgeOnepoto BridgeOnepoto Bridge is a 46 m long pedestrian / cyclist bridge crossing a bush area / tidal stream of the Onepoto area in North Shore City, Auckland, New Zealand....
, a bridge offering views of the area - Tank FarmTank FarmTank Farm is the name of a volcanic explosion crater in North Shore City, New Zealand, near the approaches to the Auckland Harbour Bridge....
, a neighbouring crater