Volcanoesof Auckland

A Field Guide
Bruce W. Hayward
Aerial photography by
Alastair Jamieson

Contents
Introduction

1

Auckland Volcanic Field

2

How the volcanoes work

4
4
6
8
11
13
13

How old is each volcano?

16
24

Auckland’s next eruption?

The magma below AucklandTime and place of Auckland’s next eruption
Monitoring for volcanic activity
The next eruption – what to expect
DEVORA
Auckland Lifelines Group

26
26
28
30
32
34
34

Human interaction with Auckland’s volcanoes

35

Volcanoes of the Waitematā Harbour and North Shore

46

Wet explosive eruptionsFire-fountaining and fiery explosive eruptions
Lava flowsVolcanic bombs and projectile blocks
Volcanic ‘hailstones’
Lava caves
Eruptions and sea levelMāori occupation and use of Auckland’s volcanoes
Volcanoes as water sources
Volcanoes lost and damaged
Tūpuna Maunga Authority

1. Rangitoto
2. Motukorea/Browns Island
3. Pupuke Moana/Pupuke Volcano		Northcote Road volcanic sequence		
Takapuna Fossil Forest and Takapuna–Milford Coastal Walk
4. Te Kopua-o-Matakamokamo/Tank Farm/Tuff Crater
5. Te Kopua-o-Matakerepo/Onepoto Basin 
6. Maungauika/North Head
7. Takarunga/Mt Victoria 
8. Takararo/Mt Cambria

35
39
42
44

48
62
70
75
77
82
86
90
96
102

Volcanoes of central Auckland

104
106
108
112
116
118
124
128
131
134
144
146
151
152
156
162
166
170
176

Volcanoes of eastern Auckland

180
182
186
190
194
201

9. Albert Park Volcano
10. Grafton Volcano
11. Pukekawa/Auckland Domain12. Te Pou Hawaiki13. Maungawhau/Mt Eden
14. Ōhinerangi/Mt Hobson/Ōhinerau
15. Te Kōpuke/Tītīkōpuke/Mt St John		
Meola Reef Te Tokaroa
16. Maungakiekie/One Tree Hill		
Hochstetter Pond and Puka Street Grotto
17. Te Tātua-a-Riukiuta/Three Kings
		Liverpool Street tuff
18. Puketāpapa/Pukewīwī/Mt Roskill
19. Te Ahi-kā-a-Rakataura/Ōwairaka/Mt Albert
20. Te Hopua-a-Rangi/Gloucester Park
21. Rarotonga/Mt Smart
22. Ōrākei Basin
23. Maungarahiri/Little Rangitoto

24. Whakamuhu/Glover Park/St Heliers
25. Taurere/Taylors Hill
26. Te Tauoma/Purchas Hill
27. Maungarei/Mt Wellington		
Maungarei Stonefields Reserve and Heritage Trail		
Waiatarua and Michaels Ave Reserve lava-flow			dammed lake and swamp
28. Te Kopua Kai-a-Hiku/Panmure Basin 
29. Ōhuiarangi/Pigeon Mountain
East Tāmaki volcanoes
30. Styaks Swamp Crater
31. Matanginui/Green Mount
32. Te Puke-o-Taramainuku/Ōtara Hill
33. Hampton Park Volcano
34. Pukewairiki/Highbrook Park
35. Te Apunga-o-Tainui/McLennan Hills
36. Ōtāhuhu/Mt Richmond37. Mt Robertson/Sturges Park

203
204
208
212
214
216
218
220
224
228
232
236

Volcanoes of southern Auckland

38. Boggust Park Crater
39. Te Pane-o-Mataaho/Māngere Mountain		Kiwi Esplanade pahoehoe flows		
Ambury Regional Park lava flows
40. Māngere Lagoon
41. Te Motu-a-Hiaroa/Puketūtū
42. Moerangi/Waitomokia/Mt Gabriel
43. Puketapapakanga-a-Hape/Pukeiti
44. Ōtuataua
45. Maungataketake/Elletts Mountain		
Ihumātao Fossil Forest
46. Te Pūkaki Tapu-o-Poutukeka/Pūkaki Lagoon
47. Crater Hill
48. Kohuora Crater
49. Cemetery Crater
50. Ash Hill Crater
51. Te Manurewa-o-Tamapahore/Matukutūruru/Wiri Mountain		Wiri Lava Cave
52. Matukutūreia/McLaughlins Mountain
53. Puhinui Craters

240
242
244
249
250
254
258
264
268
272
276
280
282
286
290
294
296
298
302
304
308

Historic basalt buildings of Auckland

310

Glossary
Select bibliography
Acknowledgements
Index

319
322
326
327

m Maungarei/Mt Wellington scoria cone from the southwest in 2018. Photo by Alastair Jamieson

Auckland Volcanic Field
Most people think of a volcano as a single large
cone that has built up by a series of eruptions
over a lifetime of thousands to hundreds ofthousands of years. All the iconic cone volcanoesof the world are of this kind and include mostof New Zealand’s best-known volcanoes, suchas Mts Taranaki, Ruapehu, Ngāuruhoe andWhakaari/White Island. Over time, this type of
volcano erupts a considerable amount of lava
and ash, often from a single vent at the centre of
the cone. They all have a magma chamber at a
relatively shallow depth (5–10 km) beneath themthat periodically clears its throat and erupts partof its contents at the surface.
Another type of volcanism occurs where there
is no magma chamber in the crust but, periodically, relatively small quantities of molten mantle
rock rise from depths of 60–90 km and erupt at
the surface. Each of these eruptions surface in2

a different location and build a relatively small
volcano that never erupts again. Volcanoes ofthis type erupt for a few days to several years
and are separated by hundreds to thousands ofyears of inactivity. They tend to erupt within adiscrete area that is called a volcanic field and the
Auckland Volcanic Field is a classic example. In
these volcanic fields the magma composition isconsistently basalt. Volcanic fields with numerous
small centres that each erupted once are called
monogenetic. The exact number of volcanoes
in the Auckland Volcanic Field depends on how
they are counted, as some cones and craters are
clustered close together and can be counted
separately or in combination. This book recognises 53 individual volcanoes.
The Auckland Volcanic Field has erupted
spasmodically over the last 200,000 years.
While it is currently dormant, the last eruption,

o The best-known symbol or iconof Auckland City is Rangitoto Island– the youngest and largest volcano
in the Auckland Volcanic Field.
q Motukorea/Browns Island
is a combination of volcanic
landforms (tuff ring, scoria cone,lava flows) produced by all threestyles of eruption that characterise
Auckland’s volcanoes. Photo by
Alastair Jamieson

Rangitoto, was only around 600 years ago andthe field is considered to be still alive and likely
to erupt again. All of Auckland’s volcanoes,
except Rangitoto, erupted on land. Sometimes
the lava probably set the surrounding forest on
fire but any evidence of this has disappeared.
Each volcano would have killed the native forest
in the immediate vicinity, and in several places
the remains of these forests are buried andpreserved by volcanic ash or lava flows. The
two best and most easily viewed examples are
at Takapuna Reef and at the end of Renton Rd,
near Auckland Airport.

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How the volcanoes work
The styles of eruption, types of rock produced and resulting landforms in Auckland’s Volcanic Field
ERUPTION STYLESCIENTIFIC TERM

ROCK PRODUCEDLANDFORM

Wet explosive

Phreatomagmatic,
Surtseyan & phreatic

Tuff (hardened volcanicash), tuff breccia

Explosion crater (maar),tuff cone or tuff ringFire-fountaining & fiery
explosive

Hawaiian & Strombolian

Scoria (lapilli, cinders),
spatter, volcanic bombs

Scoria cone(cinder cone)

Lava outpouring

Strombolian & Hawaiian

Basaltic lava

Lava flow, lava field,
or small lava shield

Wet explosive eruptions

When many of Auckland’s volcanoes firsterupted, the rising magma came into contact withnear-surface groundwater in aquifers or swampy
ground. Initially, the heat from the extremely hot
magma (about 1000–1200 ˚C) caused the water
to flash to steam, resulting in a violent explosion,
rather like what happens when cold water issplashed into a pan of extremely hot oil. These
first explosive eruptions may have involved only
steam and are referred to as phreatic or steam
eruptions. The steam blasted up through theoverlying ground, throwing out large and small
fragments of rock and soil and creating a small
crater. Deposits from these kinds of eruption
are often structureless heaps of angular blocks
in a matrix of finely comminuted soil and rock(known as tuff breccia).
Commonly, but not always, the steam blast
eruptions were followed by those that also
involved the rising magma, the surface of which
was instantly chilled, solidified and explosively
fragmented when it encountered the cold water.

4

These eruptions are called phreatomagmaticas they involve both steam and magma. They
result in the upwards and outwards ejection of a
rapidly expanding cloud of steam, magmatic gas,fragmented lava and other pieces of rock fromthe vent walls.
The solid particles that erupted into the
air and were deposited over the ground arereferred to by the general term tephra. Tephra
is divided on the basis of particle size into ash(fragments smaller than 2 mm), lapilli (2–64 mm
across), and blocks and bombs (greater than
64 mm). Wet explosive eruption columns roseto heights of a kilometre or more and the lessdense volcanic ash and lapilli within them weredispersed by the wind.
Fallout tephra accumulated on the groundon the downwind side of the volcano. Blocks ofsolid rock were ejected from the vent on ballistic
trajectories and landed nearby. Around thedenser base of the eruption column, base surgesof superheated steam, gas, ash and lapilli were
blasted out sideways at speeds up to 200 km/h.

o Cartoon of a wet
explosive eruption froman Auckland volcano. This
style of eruption typicallyforms an explosion crater
surrounded by a tuff ringcomposed of hardened
layers of volcanic ash.
Illustration by Margaret
Morleym Part of a sea cliff on Motukorea/Browns Island showing
bedded tuff. Each layer represents an explosive pulse.
Dark layers contain numerous grey basalt fragments
derived from the rising magma and cream-coloured
chunks of the underlying Waitematā Sandstone. Lightcoloured laminated beds of fine ash were left behind by
fast-moving base surges of searing gas, steam and ash.
Height of photo 0.5 m. The black basalt fragment in the
middle is a volcanic bomb in the impact crater where it
landed in the soft ash.

These turbulent base surges devastated andpartly buried areas within 3–5 km of the ventand were the most dangerous style of eruption
produced by Auckland’s volcanoes. As thesesurges passed they commonly left behind wavy
beds of fine ash, sometimes with cross-bedded
dune forms.
Wet explosive eruptions usually come in aseries of pulsating episodes interspersed by shortperiods of inactivity. These eruptions typically
produced a relatively shallow (50–100 m deep),wide (200–1000 m across), circular explosion
crater surrounded by a low ring of bedded
volcanic ash and lapilli. The ash and lapilli
were erupted wet. As the layers dried out they
hardened into a creamy-brown rock called tuff.
The raised ring of tuff rock around the explosion
crater is called a tuff ring, or, if it is a more
substantial mound, it is sometimes called a tuff
cone. A tuff ring, or cone, usually has its circularcrest forming the rim of the crater with relatively
steep slopes back into the crater and gentler
slopes (c. 5–10 degrees) on the outside. The
steeper inner slopes are often formed by a seriesof arcuate slump scarps as a result of sectionsof the tuff ring slipping back into the crater
after being deposited.
If magma supply ceased before all theground­water was used up, then the only landform produced by the volcano was an explosion

5

crater surrounded by a tuff ring. There are 24
explosion craters with surrounding tuff rings in
the Auckland Volcanic Field.
The rock fragments that were blasted out inthese explosive eruptions include many pieces
ripped from the walls of the volcano’s throat.
They range in size from small lapilli to large blocks
more than a metre across. The composition ofthese ejected rocks provides information on therock strata that underlie the volcano at depths ofseveral hundred metres or more. In a way, these
volcanoes were natural drilling rigs, bringing
samples of rock to the surface for geologists
to piece together and work out the underlying
rock sequence.
After eruptions finished, the explosion craters
gradually filled with rainwater, creating crater
lakes. Many of these lakes have subsequently
filled with sediment and are now tidal lagoons,swamps or reclaimed wetlands. Those that
became tidal lagoons were formerly lakes
that were breached by rising sea level about
8000 years ago as a result of the melting of theEuropean and North American ice sheets after
the end of the Last Ice Age.

6

Fire-fountaining and fiery
explosive eruptions

If the water in the vent was all used up (during
the wet explosive eruptions) before the magma
supply waned, then eruptions switched to a dry
style and scoria cones were built. These partly orcompletely filled the explosion crater and maybe
even buried all trace of the tuff ring.
The magma that erupted to form Auckland’s
volcanoes was molten rock containing dissolvedgas (mostly water vapour and carbon dioxide)
under pressure, rather like the dissolved gas in abottle of fizzy drink. As the rising magma neared
the surface, pressure reduced and the releasinggas drove a fountaining of frothy liquid fromthe vent, called fire-fountaining. Shake up abottle of Coca-Cola, remove the lid, partly close
the opening with your thumb and watch thefountaining powered by the escaping gas – so it
is with natural fire-fountaining.
As the fountaining frothy lava flew throughthe air, it cooled and solidified, forming thefrothy rock known as scoria (sometimes calledcinders). This rock is initially black but oxidationof iron (reaction with oxygen in the air) during

o View from Māngere Mountain across Māngere Lagoon
explosion crater and surrounding tuff ring with a small
restored scoria cone in the middle.

m Cartoon of a fire-fountaining eruption that produced
a scoria cone with a steep-sided central crater. Illustrationby Margaret Morleyq Time-elapse photo of a fiery explosive eruption(Strombolian) in Hawai‘i at night. Courtesy of US
Geological Survey

fountaining turned much of the hot scoria to its
characteristic red colour. Scoria that remained
black erupted on the margins of the fountain andcooled too quickly to react with the atmosphere.
The erupted scoria accumulated around thevent, building a steep-sided scoria cone with adeep crater. The slope of scoria cones is about
30 degrees, the angle at which scoria came torest as it rolled downhill. A 30-metre-high scoria
cone can be thrown up in less than a week and a
100-metre-high cone in several weeks. If a strong
wind was blowing during fountaining, much of thescoria landed on the downwind side of the vent,building up a higher peak on one side of the scoria
cone (e.g. One Tree Hill).
Scoria cones consist of layers of scoria ofvarious sizes. Larger and denser fragments landed
closer to the vent and the smallest lapilli andscoriaceous ash could be blown many kilometresaway (e.g. Three Kings fountaining eruptions).
Auckland’s scoria cones were built mostly bysteady fire-fountaining eruptions of rapidly
rising, rather fluid magma containing multitudesof small gas bubbles. Sometimes this magma
was still sufficiently liquid when it landed that it
joined together to form a small lava flow that ran
part-way down the cone slopes before coolingand solidifying. These small flows within a scoria
cone are often called rootless lava flows because
they differ from normal flows in that they haveno obvious link to their source deep in the throatof the volcano.
Within some of the scoria cones there arelayers of larger, ragged chunks of coarsely
vesicular (holey) or more dense basalt thatwere expelled from the vent by discrete fiery
explosive eruptions (called Strombolian style)of more pasty lava. These incandescent lumps
often landed in a sticky molten form and tended
to weld together into hard layers. The rate ofmagma ascent usually determines the style oferuption and the character of the ejected lava.
The discrete fiery explosive outbursts occurredat fairly regular intervals seconds to minutes
apart, and indicate more slowly rising, less fluid7m A fire-fountaining (Hawaiian) eruption in Hawai‘i.
Notice how the wind has blown the column so thatthe scoria lands on one side of the vent. Courtesy of
US Geological Survey
q Well-sorted red scoria produced by fire-fountaining.
The lumps of scoria are honeycombed with small holes(called vesicles) that were once bubbles in the erupting
frothy lava.

8magma. Some of the small gas bubbles coalescedand grew extremely large as they rose throughthe magma column, each bursting at the surface
to produce a separate explosive blast ejecting
lumps of fiery lava tens to hundreds of metresinto the air.
These discrete fiery explosive eruptions
often occurred towards the end of the dry
fire-fountaining phase as the rate of magma
ascent slowed and it became cooler, thicker andless gaseous. As a result, a number of Auckland’sscoria cones are capped by partly welded depositsof large, ragged lumps of scoriaceous basalt andaerodynamically shaped volcanic bombs (e.g.
McLaughlins Mountain, Mt Wellington, Big Kingand Little Rangitoto).
Over half of Auckland’s volcanoes produced
one or more scoria cones erupted by a combination of fire-fountaining and fiery explosive
eruptions, although many have been damaged or
removed by quarrying in recent times. Several of
the smallest cones (e.g. Pukeiti, Te Pou Hawaiki
and Hampton Park) are composed almost entirelyof the more welded deposits thrown out by fiery
explosive eruptions.

Lava flows

During the dry fire-fountaining and fiery explosive phase of eruption of Auckland’s scoria cones,
the partly degassed molten magma often rose up
inside the throat of the volcano. If it reached theheight of the base of the scoria cone, this magma
could push its way through the loose scoria andemerge as a flow of lava from near the base of
the cone. Sometimes the loose scoria collapsed
and the side of the scoria cone was rafted awayby the outflowing lava. Such action created ahorseshoe-shaped or breached crater (e.g. on
Mt Hobson and One Tree Hill). Any scoria thatlanded on the lava flowing through the breach
was also rafted away.
The outpouring of lava flows was usuallyaccompanied by fire-fountaining or fiery explosions. Gas in the fluid magma was released in the
volcano’s throat and powered the fiery eruptions

m Maungawhau/Mt Eden’s steep-sided scoria cone was built by fire-fountaining and fiery explosive eruptions of bubbly
lava (scoria) from two craters. The southern crater is the most obvious. Photo by Alastair Jamieson, 2018from the vent directly above; whereas the lava
that flowed out the side had lost most of its
dissolved gas and, when it cooled and solidified,
it became a relatively dense, dark grey basaltic
rock. Some gas that was still trapped in the lava
often rose towards the surface of the flow as itcooled. This sometimes resulted in a zone of morevesicular, or holey, basalt near the top of the flow.
As molten basaltic lava cools and solidifies, it
contracts and cooling cracks form. These cracks
often form fairly regular hexagonal-shaped
columns (called columnar joints) that are vertical(or, more accurately, perpendicular to the coolingsurfaces at the top and bottom of the flow).
Sometimes, near-horizontal cooling joints also
form near the top or bottom of a flow.
The size of the lava flow or field of coalescinglava flows depended on the supply of lava. Someof Auckland’s cones produced just one small flow
(e.g. Little Rangitoto and North Head), whereas
others produced sizeable lava-flow fields thatcompletely surrounded them (e.g. Māngere
Mountain and Mt Eden). The speed and distancetravelled by individual flows was controlled by
the eruption rate and temperature of the erupted
lava and hence its viscosity. The hotter, more
liquid lava flowed downhill at running pace. Its
surface chilled quickly to a thin, elastic black crust
but the fluid lava beneath continued to flow anddeform the surface skin into curved, ropey rolls,
rather like the skin on a pot of cooling jam. Flows
with such a smooth surface texture are known by
their Hawaiian name as pahoehoe flows. As theflows moved downhill they cooled and became
stickier, eventually stopping and solidifying into
basalt rock.

9m Cartoon cross-section of the plumbing and eruptionstyle that resulted in the outpouring of lava flows fromthe base of an Auckland scoria cone. Illustration by
Margaret Morleyq A pahoehoe lava flow in Hawai‘i showing thecharacteristic cooled, black crust with its ropey rollson the surface of the still molten lava. Courtesy of
US Geological Survey

m Typical rubbly surface of an a‘a lava flow on Rangitoto
Island.

10

Towards the end of a volcano’s eruptive
history, the magma in the plumbing began to cooland the erupted lava flows were more viscous.
They flowed more slowly and often came to a
standstill not far from the vents from which theyoozed (e.g. One Tree Hill and Mt Eden). These
cooler, more viscous lava flows formed thicker,
more solid surface crusts that behaved brittly andnot elastically. This thick crust was broken up into
sharp blocks of rotating basalt by the continued
movement of the fluid lava interior of the flow.
These flows, which look like a moving pile ofrocky rubble, are known by their Hawaiian nameas a‘a flows.
The two Auckland volcanoes that erupted
the largest volume of lava are One Tree Hill andRangitoto. Over several years, numerous flows
poured out from around the base of their growing
scoria cones. These flows cooled and solidified
on top of each other to build up roughly circularcones with gentle slopes of about 10 degrees.
These gently sloping lava-flow cones are small
shield volcanoes – Rangitoto’s is the bestdeveloped, and One Tree Hill’s is less so andbest viewed from the south. McLennan Hills also
built up a small shield volcano. All three werecapped by several coalescing, steeper scoria
cones at the centre.
Where the volume of outpouring lava wasless, the shape of the land over which it erupted
influenced the resulting form of the lava-flow
field. Flows that erupted onto the relatively flat
Manukau lowlands generally spread out as a wide
apron close to the central cone (e.g. Māngere
Mountain and Ōtuataua). The Auckland Isthmus
was more dissected with incised streams draining
rolling sandstone hill country. In this area,
outpouring lava flowed as viscous rivers down
stream valleys and cooled to form solid ribbons
of basalt filling the valley floors (e.g. the Three
Kings and Mt Wellington flows). The streams
were displaced and now flow along the side of thebasaltic flows, eroding new courses into the softer
sandstone banks (e.g. Oakley, Meola, Motions
and Puhinui creeks).

1

Rangitoto

Rangitoto

Visitors to iconic Rangitoto Island arrive by ferryat Rangitoto Wharf on the south side of the island(foreground) and usually walk the track to the summit
for views over Auckland. Photo by Alastair Jamieson

49

1

1

Rangitoto

o Aerial view of the southern slopes ofRangitoto Island showing the different
vegetation (darker) growing on themain scoria cone compared with the
pōhutukawa forest on the lava flows.
In the foreground, branching lobes ofsome of the youngest lava flows formed
as they entered the sea. Photo by
Alastair Jamieson, 2009Land status: Rangitoto Island is a Crown-owned scenic reserve, as is adjacent Motutapu Island
Recreation Reserve. Both are managed by the Department of Conservation and fully open to
the public.
How to get there: Catch a Fullers ferry from the ferry buildings in Quay St, downtown Auckland orfrom Devonport Wharf. They take passengers to and from Rangitoto Wharf several times a day.
See www.fullers.co.nz/destinations/rangitoto-island/ for times and fares. Make sure you know thetime of the last returning ferry because if you miss it you may have to hire an expensive water taxi
to bring you back.
What to do: Spend a half or full day on Rangitoto Island. On a half-day trip there is time to walk tothe summit for a panoramic view of Auckland and the Hauraki Gulf (2 hours return) and appreciate
the rubbly lava flows and steeper scoria cone at the top. There may also be time for a quick visit

50

Rangitotoo Some of the lava flows traversedby the track to the summit from
Rangitoto Wharf have a surface of
broken-up slabs of basalt (up to 1 m
across) that probably cooled andsolidified on the top of relatively fluid
pahoehoe lava. As these flows cooled
they became more viscous and slower,
and this surface crust was ripped apartand rafted along as slabs.

to the lava caves. An alternative for less fit visitors is to pay for a road-train ride on the gravel roadaround the island with a stop near the summit for an opportunity to climb the wooden boardwalk andsteps to the summit.
On a full-day visit (6 hours) there is time to walk to the summit, visit the lava caves and return toRangitoto Wharf on the rocky road via Islington Bay (east side) or McKenzie Bay (west side). Bothroutes are 7 km. Around Islington Bay and Rangitoto wharves there are additional picturesque coastal
walks past the sites of many of the former holiday baches that once lined the rocky shore. Just a few
baches are still standing as historic reminders of a bygone era. For those interested in plants, examine
the plant successions on the lava flows and the scoria cone using the main tracks or from side tracks,
such as Kidney Fern and Wilson’s Park tracks. On a hot summer’s day, swim at the sandy beach at
McKenzie Bay (1 hour’s fast walk each way from Rangitoto Wharf) or, if the tide is in, there is a small
artificial pool near Rangitoto Wharf. There is no shop on the island and the only toilets and fresh water
are at Rangitoto Wharf, Islington Bay and McKenzie Bay.

o This 2-metre-high, conical tower of basalt spatter near
the track to the lava caves is called a hornito. Rangitotois the only place in New Zealand where hornitos arepreserved. Hornitos are small mounds of welded spatterbuilt by the accumulation of incandescent lava ejected
through holes in the roof of a lava tube within a lava flow.

51

1

1

Rangitoto

o Profile of Rangitoto from Ōkahu Bay
showing the gentle lower slopes of thelava-flow shield surmounted by the
steeper main scoria cones. The twosecondary scoria cones on either sideof the main one are clearly visible fromthis part of Auckland City.

52

Rangitotoo Places of interest on Rangitoto Island:
1. Rangitoto Wharf. Shelter with information panels andwater. If the tide is low, look over the sea wall adjacentto the shelter to see a well-exposed branching pahoehoe lava flow that was formed as molten lava reached
the sea.
2. Second World War parade ground. This originally
was an unfinished tennis court constructed by theprisoners who were housed in a camp close by.
3. A‘a and slab pahoehoe lava flows and levees. Look fortrenches margined by ridges of rubble (called levees)
formed where molten lava drained out of the centre of
the lava flow and the overlying rubble collapsed into
the empty conduit, producing a trench.
4. Side track to the lava caves (10 minutes each way)
leaves the Summit Track at the foot of the scoria
cones. Track leads to a 100-metre-long cave with an
unusual trench-like shape and near-vertical walls. This
was the internal conduit for lava that flowed along
within an a‘a flow with an outer carapace of solidified
clinker blocks of basalt. When the lava drained out itleft this long lava tube. Entry and exit points are where
the roof has collapsed. If you intend to explore thesecaves you should take a torch and wear a thick hat forprotection in case you bump your head on the roof.
5. Depressed moat where the track to the caves branchesfrom the Summit Track. It separates the top of the lava
flows and the scoria cones. The track to the caves runs
through this moat for some distance. It was probably
formed by the slight subsidence of the scoria cones
into the vent as lava withdrew back down the volcano’s
throat at the end of Rangitoto’s eruptions.
6. Summit. Superb views into the crater and out over
the Waitematā Harbour, Hauraki Gulf and Motutapu
Island. The small concrete building was the firecommand post used to co-ordinate Auckland’s coastal
defence gun batteries during the Second World War.
7. Islington Bay Wharf and historic baches.
8. Causeway to Motutapu Island constructed on topof a shell spit during the Second World War to link
defensive posts on both islands.

9. Old Harbour Board quarry and site of controlled minebase during the Second World War.
10. Wreck Bay. Reached via a rough side track (1 hour
each way) off the road between Islington Bay and thesummit. The low cliffs on either side of the bay andthe huge boulders thrown up above high tide attest
to the power of major storms that have carved into
the basaltic lava flows on the exposed north side ofRangitoto since they were erupted just 600 years
ago. The sheltered south side of Rangitoto has had
almost no erosion.
11. McKenzie Bay, along with adjacent Whites Beach,is the only sandy beach on Rangitoto. It was thesite of a short-lived (1892–96) salt refinery whereimported rock salt was dissolved in sea water andthen refined salt crystals were produced from thebrine by evaporation in a huge pan heated by four
furnaces. Nearby on an offshore islet is Rangitoto
Beacon (built in 1887) – one of the first structures
built on the island and used for sea navigation. It was
initially lit by gas but switched to electricity in 1929.
12. Flax Point. Site of Auckland’s largest black-backed
gull colony.

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