The
Waikato
Waikato () is a Regions of New Zealand, local government region of the upper North Island of New Zealand. It covers the Waikato District, Waipa District, Matamata-Piako District, South Waikato District and Hamilton, New Zealand, Hamilton City ...
and
King Country
The King Country (Māori: ''Te Rohe Pōtae'' or ''Rohe Pōtae o Maniapoto'') is a region of the western North Island of New Zealand. It extends approximately from the Kawhia Harbour and the town of Otorohanga in the north to the upper reaches of ...
regions of
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
are built upon a basement of
greywacke
Greywacke or graywacke (German ''grauwacke'', signifying a grey, earthy rock) is a variety of sandstone generally characterized by its hardness, dark color, and poorly sorted angular grains of quartz, feldspar, and small rock fragments or lit ...
rocks, which form many of the hills. Much of the land to the west of the
Waikato River
The Waikato River is the longest river in New Zealand, running for through the North Island. It rises on the eastern slopes of Mount Ruapehu, joining the Tongariro River system and flowing through Lake Taupō, New Zealand's largest lake. It th ...
and in the King Country to the south has been covered by
limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
and sandstone, forming bluffs and a
karst landscape
Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant ro ...
. The volcanic cones of Karioi and Pirongia dominate the landscape near Raglan and Kawhia Harbours. To the east, the land has been covered with
ignimbrite
Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrou ...
deposits from the
Taupo Volcanic Zone. Large amounts of
pumice
Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicular vol ...
from the Taupo Volcanic Zone have been deposited in the Waikato Basin and
Hauraki Plains
The Hauraki Plains are a geographical feature and non-administrative area (though Hauraki Plains County Council existed from 1920 to 1989 and a statistical Area Unit remains) located in the northern North Island of New Zealand, at the lower ( ...
.
Basement rocks
As with most of New Zealand, the basement rocks of the Waikato Region and King Country are composed of greywacke (indurated
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates) ...
,
siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...
and
mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...
).
The
Waipa Fault passes north–south through the Waikato-King Country region, from
Taupiri
Taupiri is a small town of about 500 people on the eastern bank of the Waikato River in the Waikato District of New Zealand. It is overlooked by Taupiri mountain, the sacred burial ground for the Waikato tribes of the Māori people, located ju ...
, along the
Waipā River
The Waipā River is in the Waikato region of the North Island of New Zealand. The headwaters are in the Rangitoto Range east of Te Kuiti. It flows north for , passing through Ōtorohanga and Pirongia, before flowing into the Waikato River at ...
, and south to near
Ohura. It represents a major dividing line between different
terrane
In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its own ...
s.
Murihiku Terrane
The Southland Syncline is a major geological structure located in the Southland Region of New Zealand's South Island. The syncline folds the Mesozoic greywackes of the Murihiku Terrane. The northern limb of the fold is steep to overturned, while ...
greywacke lies beneath the Waikato-King Country region on the western side, and outcrops to the west of the Waipa Fault, from south of
Waikato Heads to
Awakino
Awakino is a settlement in the south of Waitomo District, in the North Island of New Zealand. It is located on State Highway 3 at the mouth of the Awakino River, five kilometres north of Mokau. It is 79 km southwest of Te Kuiti, and 98&n ...
. The Murihiku Terrane is considered to be an accretionary wedge of mainly
volcano
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
On Earth, volcanoes are most often found where tectonic plates are ...
genic
forearc
Forearc is a plate tectonic term referring to a region between an oceanic trench, also known as a subduction zone, and the associated volcanic arc. Forearc regions are present along a convergent margins and eponymously form 'in front of' the vol ...
sediments. It was formed in
Late Triassic
The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ...
to
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987.
In European lithostratigraphy, the name ...
times (220-145 Ma).
A line of
Dun Mountain-Maitai Terrane
The Dun Mountain-Maitai Terrane comprises the Dun Mountain Ophiolite Belt (also called the Mineral Belt), Maitai Group and Patuki Mélange. The Dun Mountain Ophiolite is an ophiolite of Permian age located in New Zealand's South Island
The So ...
rocks are assumed to pass north–south along the Waipa Fault, through the centre of the Waikato-King Country region, separating the Murihiku Terrane and
Waipapa Composite Terrane
Waipapa is a small town in the Bay of Islands, Northland, New Zealand. It is around 10 minutes drive from Kerikeri, the nearest urban centre to Waipapa, located on State Highway 10. Waipapa itself has no school and most people travel into Ke ...
, and produce a detectable Junction
Magnetic Anomaly
In geophysics, a magnetic anomaly is a local variation in the Earth's magnetic field resulting from variations in the chemistry or magnetism of the rocks. Mapping of variation over an area is valuable in detecting structures obscured by overlying ...
, but only outcrops at one place, at
Wairere. Some Murihiku rocks occur to the east of the Junction Magnetic Anomaly, forming the Taupiri and
Hakarimata Ranges, but it is assumed that these rocks have been shifted to their present position.
The Waipapa Morrinsville Terrane greywacke lies beneath the Waikato-King Country region on the eastern side, south of the
Hunua Ranges
The Hunua Ranges is a mountain range and regional park to the southeast of Auckland city, in the Auckland and Waikato regions of New Zealand's North Island. The ranges cover some and rise to 688 metres (2255 ft) at Kohukohunui. , and east of the Waipa Fault. It was formed in Late Jurassic to
Early Cretaceous
The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma.
Geology
Pro ...
times (160-120 Ma).
Te Kuiti Group coal and limestone
The Te Kuiti Group rocks overlie the basement rocks, and are present in
Northland,
Auckland
Auckland (pronounced ) ( mi, Tāmaki Makaurau) is a large metropolitan city in the North Island of New Zealand. The List of New Zealand urban areas by population, most populous urban area in the country and the List of cities in Oceania by po ...
, the Waikato, and King Country, although they have often been eroded or covered. Rocks containing coal were formed from swampland in
Late Eocene
The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "daw ...
times (37-34 Ma). The land sunk and the sea transgressed, and
calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.
In zoology
''Calcareous'' is used as an adje ...
sandstone, mudstone, and limestone were deposited in
Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...
times (34-24 Ma).
The coal deposits outcrop near
Huntly
Huntly ( gd, Srath Bhalgaidh or ''Hunndaidh'') is a town in Aberdeenshire, Scotland, formerly known as Milton of Strathbogie or simply Strathbogie. It had a population of 4,460 in 2004 and is the site of Huntly Castle. Its neighbouring settlemen ...
and
Maramarua
Maramarua is a locality in the north-eastern part of the Waikato District of New Zealand. State Highway 2 runs through the settlement.
Demographics
Maramarua settlement is in an SA1 statistical area which covers . The SA1 area is part of the ...
, where they are mined.
Limestone exists in the area south and west of the
Waikato River
The Waikato River is the longest river in New Zealand, running for through the North Island. It rises on the eastern slopes of Mount Ruapehu, joining the Tongariro River system and flowing through Lake Taupō, New Zealand's largest lake. It th ...
, down to
Piopio and
Te Kuiti, producing impressive bluffs around Port Waikato, Raglan Harbour, Kawhia Harbour, Otorohanga, Waitomo, Te Kuiti, etc. The
Karst landscape
Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant ro ...
around
Waitomo
Waitomo is a rural community in the King Country region of New Zealand's North Island. There are several solutional cave systems in the area around the village, which are popular tourist attractions. Restaurants and accommodation are centred in ...
contains many cave systems, including the
Waitomo Glowworm Cave
The Waitomo Glowworm Caves attraction is a cave at Waitomo on the North Island of New Zealand. It is known for its population of '' Arachnocampa luminosa,'' a glowworm species found exclusively in New Zealand. This cave is part of the waitomo ...
.
Miocene sediment
In early Miocene times (24 Ma), plate convergence caused regional compression. The land eroded, and was deposited throughout the Miocene (24-5 Ma) in rapidly subsiding basins. These soft sandstones and mudstones remain to the southwest of Te Kuiti.
Mohakatino Volcanic Arc
The volcanic arc that developed to the west of Northland and Auckland extended further south towards Taranaki. These andesitic and basaltic volcanoes were mostly active in middle
Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
times (14-11 Ma), and contributed to the sandstone and mudstone deposits that formed around that time.
Recent volcanic activity
Mount Karioi and
Mount Pirongia
Mount Pirongia is an extinct stratovolcano located in the Waikato region of New Zealand's North Island. It rises to 959 metres and is the highest peak in the Waikato region. It was active in the late Pliocene and early Pleistocene times. ...
, near Raglan and Kawhia Harbours, are large
stratovolcano
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and per ...
es composed of
andesite
Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomi ...
and
basalt
Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...
, that erupted about 2.5 Ma ago. Other volcanoes in this group include
Kakepuku
Kakepuku (Kakipuku-o-kahurere) is a volcanic cone which rises from the plain between the Waipā and Puniu rivers, about NW of Te Kawa and SW of Te Awamutu in the Waikato region of New Zealand's North Island.
Geology
The 'Geology of the Wa ...
,
Te Kawa
Te Kawa is a rural community in the Ōtorohanga District and Waikato region of New Zealand's North Island. It lies just to the south of the volcanic hills of Kakepuku and Te Kawa. Until the swamp was drained in the 1900s, Te Kawa was well know ...
, and Tokanui.
Maungatautari, west of Te Awamutu, is a volcano, composed of andesite and
dacite
Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. ...
, that erupted about 1.8 Ma.
Ignimbrite and pumice deposits
Over the last 2 million years,
pyroclastic
Pyroclastic rocks (derived from the el, πῦρ, links=no, meaning fire; and , meaning broken) are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyroc ...
flows from the
Taupo Volcanic Zone have deposited
ignimbrite
Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrou ...
s over the area East of Te Kuiti. Some of the largest deposits are from the Whakamaru eruption, north of Taupo, around 330,000 years ago. The ignimbrite deposits from the Oruanui eruption 26,500 years ago, and the Taupo eruption, 1800 years ago are also major deposits. They form impressive cliffs in many areas.
The
Hauraki Plains
The Hauraki Plains are a geographical feature and non-administrative area (though Hauraki Plains County Council existed from 1920 to 1989 and a statistical Area Unit remains) located in the northern North Island of New Zealand, at the lower ( ...
and
Hauraki Gulf
The Hauraki Gulf / Tīkapa Moana is a coastal feature of the North Island of New Zealand. It has an area of 4000 km2,[rift valley
A rift valley is a linear shaped lowland between several highlands or mountain ranges created by the action of a geologic rift. Rifts are formed as a result of the pulling apart of the lithosphere due to extensional tectonics. The linear dep ...](_blank)
. The rift valley is assumed to have developed about 2 Ma ago, due to the clockwise rotation of the Eastern North Island, that stretched the land between Auckland and East Cape. The Waikato River used to flow from
Lake Karapiro
Lake Karapiro () is an artificial reservoir lake on the Waikato River at Karapiro, south-east of Cambridge in New Zealand's North Island. The lake was formed in 1947 by the damming of the Waikato River to store water for the 96-megawatt Karap ...
, through the
Hinuera Gap
Hinuera is a settlement in the Waikato Region of New Zealand's North Island. It is located along State Highway 29, approximately halfway between the cities of Hamilton and Tauranga. It also contains the Hinuera cliffs along State Highway 29 ...
, and Hauraki Plains, to come out on the east coast in the Hauraki Gulf. The sediment from the 26.5 ka
Oruanui eruption
The Oruanui eruption of New Zealand's Taupō Volcano (also known as the Kawakawa eruption or Kawakawa/Oruanui event) was the world's most recent Supervolcano#Known supereruptions, supereruption.}
Eruption
With a Volcanic Explosivity Index of 8, ...
of
Lake Taupo
A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...
caused the river to change direction, and come out to the west. In fact, the Waikato River changes its route quite regularly, as eruptions occur in the Taupo Volcanic Zone, and the river channel becomes blocked. Many lakes and swamps in the Waikato Basin represent old routes.
Pumice from the Taupo Volcanic Zone has been deposited throughout the Waipa and Waikato Basins, and the Hauraki Plains, forming excellent soils and swampland.
Tauranga Group
Tauranga Group describes sediments of the last 5 million years, mainly of volcanic pumice, initially
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58[Coromandel
Coromandel may refer to:
Places India
*Coromandel Coast, India
**Presidency of Coromandel and Bengal Settlements
** Dutch Coromandel
*Coromandel, KGF, Karnataka, India
New Zealand
*Coromandel, New Zealand, a town on the Coromandel Peninsula
*Coro ...](_blank)
and latterly
Holocene
The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...
from Taupo (Piako Subgroup). They underlie the Hamilton lowlands and extend into the Waipa basin, but elsewhere are mainly
alluvial
Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluv ...
deposits in valleys. As well as pumice gravels and sands, they include silts, muds and peat.
Coastal dunes
Substantial sand dunes with high iron content have formed around the
Kawhia
Kawhia Harbour (Maori: ''Kāwhia'') is one of three large natural inlets in the Tasman Sea coast of the Waikato region of New Zealand's North Island. It is located to the south of Raglan Harbour, Ruapuke and Aotea Harbour, 40 kilometres southwe ...
and
Aotea Harbours.
David Kear's 'Geology of Ironsand Resources of New Zealand' (NZ Dept of Scientific & Industrial Research 1979) says, "The ironsand deposits extend from south Kaipara and Muriwai, north of Auckland, for over 300 miles southwards to the Whangaehu River, south of Wanganui". Soluble iron in concentrates exceeds 50% in most locations. It is currently mined at
Taharoa
Taharoa ( mi, Tahaaroa or ) is a small village on the west coast of the North Island of New Zealand, to the southwest of Kawhia Harbour and overlooking Lake Taharoa.
The New Zealand Ministry for Culture and Heritage gives a translation of "lo ...
and
Waikato North Head
Otaua is a rural settlement in the Waikato District and Waikato region of New Zealand's North Island. It is located south of Waiuku and west of Aka Aka, on the northern side of the Waikato River. The Otaua area includes the Waikato North Head on ...
.
Geological sites worth visiting
*Hinuera Gap, State Highway 29, between Lake Karapiro and Matamata is the course of the Waikato River, before it changed to go through Hamilton. The cliffs on either side show how big the river was.
*Much of the Western hill country from
Waikato Heads down to
Te Kuiti contains interesting limestone countryside, with impressive bluffs. However, you need to take the small, unsealed roads to see much. The
Lake Disappear
Lake Disappear is an intermittent volcanogenic lake (see also turlough and polje) situated in the North Island of New Zealand, just over 20 km from Raglan, 4 km beyond Bridal Veil waterfall. It has also been described as a solution ...
polje is on one of these roads.
*The
Waitomo
Waitomo is a rural community in the King Country region of New Zealand's North Island. There are several solutional cave systems in the area around the village, which are popular tourist attractions. Restaurants and accommodation are centred in ...
Area contains excellent examples of a
Karst landscape
Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant ro ...
, and several tourist caves, including the most famous
Waitomo Glowworm Cave
The Waitomo Glowworm Caves attraction is a cave at Waitomo on the North Island of New Zealand. It is known for its population of '' Arachnocampa luminosa,'' a glowworm species found exclusively in New Zealand. This cave is part of the waitomo ...
.
*The
Raglan, Aotea, and
Kawhia
Kawhia Harbour (Maori: ''Kāwhia'') is one of three large natural inlets in the Tasman Sea coast of the Waikato region of New Zealand's North Island. It is located to the south of Raglan Harbour, Ruapuke and Aotea Harbour, 40 kilometres southwe ...
Harbours are worth a visit, especially the dissected hill country around Raglan formed on greywacke basement rocks, the limestone countryside, the sand dunes and beach near Kawhia, and Albatross Point west of Kawhia Harbour.
*Karioi and Pirongia volcanoes are well worth climbing, for those with sufficient fitness. A drive around Karioi has impressive scenery, especially the
Te Toto Gorge.
*Wairere has the one outcrop of serpentine in the North Island.
*Mangpehi Mine, near Benneydale is an abandoned coal mine.
*The coastal highway down to Taranaki has rugged sandstone cliffs, and black sand beaches.
*The road from Te Kuiti through to Atiamuri has impressive Whakamaru Group welded ignimbrite cliffs.
Maps
Geological maps of New Zealand can be obtained from the New Zealand Institute of Geological and Nuclear Science (GNS Science), a New Zealand Government Research Institute.
GNS provides a free Map of New Zealand's Geological Foundations.
The main maps are the 1 : 250 000 QMap series, which will be completed as a series of 21 maps and booklets in 2010. Low resolution versions of these maps (without the associated booklet) can be downloaded from the GNS site for free.
GNS New Zealand Geological Maps
. The map for the Waikato Area was published in 2005.
See also
*Geology of New Zealand
The geology of New Zealand is noted for its volcanic activity, earthquakes and geothermal areas because of its position on the boundary of the Australian Plate and Pacific Plates. New Zealand is part of Zealandia, a microcontinent nearly half th ...
a list of the most significant Waikato geological features
References
Further reading
*Graham, Ian J. et al.; ''A continent on the move : New Zealand geoscience into the 21st century'' - The Geological Society of New Zealand in association with GNS Science, 2008.
{{DEFAULTSORT:Geology Of The Waikato-King Country Region
Waikato
Waikato () is a Regions of New Zealand, local government region of the upper North Island of New Zealand. It covers the Waikato District, Waipa District, Matamata-Piako District, South Waikato District and Hamilton, New Zealand, Hamilton City ...
Geography of Waikato
Geography of Manawatū-Whanganui