Geography 3.1 (Tongariro Geographic Area)

Terms and Definitions for 3.1 External. Based on Te Kura GYO3004 and GYO3005

Plate tectonics

Plate tectonics

Scientific theory that describes the large-scale motion of Earth's lithosphere (crust), which is divided into several plates that float on the semi-fluid asthenosphere

Volcanism

The process by which magma, gas, and ash erupt onto the Earth's surface through volcanoes, creating new landforms and releasing pressure from the Earth's interior

Pyroclastic

Fragments of rock and debris from a volcanic eruption

Pyroclastic eruption

A rapid and explosive volcanic eruption that releases hot ash, rocks, and gases into the atmosphere at high speeds

Basic magma

Has low silica content and is less viscous, allowing gases to escape easily. It often leads to gentle volcanic eruptions

Where can basic magma be found in NZ?

Auckland and Northland

Acidic magma

Has high silica content, making it viscous with explosive eruptions. It forms light-colored rocks like rhyolite

Where can acidic magma be found in NZ?

Taupo-Rotorua volcanic zone; Taupo to Bay of Plenty

Intermediate magma

Has a silica content between that of basaltic and rhyolitic magma

Where can intermediate magma be found in NZ?

Taranaki and Tongariro regions

Composite cone

A volcano formed by alternating layers of lava flows and pyroclastic material, such as ash and volcanic rocks. It has a steep profile and can erupt explosively. Formed during andesitic eruptions. Example: Ruapehu

Shield volcano

A broad, gently sloping volcano characterized by flowing lava and built from many eruptions. Example: Rangitoto Island

Caldera

A large volcanic crater formed by the collapse of a volcano after an eruption, often filled with water. Example: Lake Taupo

Tephra

Fragments ejected during a volcanic eruption, including ash, lapilli, and bombs. Vary in size and composition, impacting landscapes and air quality

Hot springs

Natural bodies of water heated geothermally by the Earth's crust. They are formed when groundwater comes into contact with hot rocks below the surface, heating the water and bringing it back to the surface in the form of a spring. Example: Ketetahi Springs

Fumarole

An opening in or near a volcano, emitting steam and gases like sulfur dioxide. It results from the heating of groundwater

Sills

Horizontal igneous rock formations that form when magma intrudes between layers of existing rock and solidifies underground

Dykes

Vertical sheets of igneous rock that cut across the layers of pre-existing rock in the Earth's crust, formed by the intrusion of magma

Explosion crater

A bowl-shaped depression formed by the explosion of a volcanic vent, often filled with water or lava

Fault lines

Fractures in Earth's crust where rocks on either side have moved relative to each other. They are responsible for earthquakes due to the release of built-up stress

Fire-fountaining

Volcanic eruption where lava is ejected into the air, forming fountains of molten rock

Scoria cone

A steep-sided volcanic cone made of fragmented volcanic rock, forming from explosive eruptions of gas-rich magma

Height of Mt. Tongariro

1964m

Height of Mt. Ngauruhoe

2291m

Height of Mt. Ruapehu

2797m

Lahar

A fast-moving volcanic mudflow consisting of a mixture of volcanic debris, water, and mud

How do crater lakes make volcanoes more dangerous?

Crater lakes can cause explosive eruptions when heated by magma, leading to sudden releases of gas and ash

How do snowfields make volcanoes more dangerous?

Snowfields on volcanoes can melt rapidly during an eruption, causing lahars that can travel quickly down the slopes

Tongariro, Ruapehu, and Ngauruhoe are examples of ________ volcanoes

Andesite

Taupo is an example of a ________ volcano

Rhyolite

The Pacific - Australian plate margin is an example of a _______ margin

Collsion/subduction

At divergent plate margins, the plates ________

Move apart

At transform plate margins, the plates _________

Slide past each other

At collision plate margins, the plates __________

Collide; converge; subduct; move towards each other

Geographic environment

Refers to the physical surroundings of an area, including landforms, climate, vegetation, and natural resources

Natural features

Landscape features (or phenomena) that are a result of natural processes

Processes

A series of actions or events that shape and change environments

Location

Where features are sited

Spatial variation

Differences or changes in characteristics across different locations or areas

Temporal variation

Refers to changes or fluctuations that occur over time in a particular phenomenon or system

Dispersal

When the effects of a process are large-scale and affect a large area

Concentrated

When the effects of a process are localised an affect a small area

Age of Mt. Tongariro

275,000 years

Age of Mt. Ngauruhoe

2,500 years

Age of Mt. Ruapehu

250,000 years

When was Ruapehu’s last large eruption?

1995-96

When was the last eruption of the Taupo volcano?

232 AD

When was the last eruption of Mt. Ngauruhoe?

1975

Average annual rainfall at Chateau Tongariro (1097m asl)

2754mm

Average annual rainfall at Ohakune (820m asl)

1412mm

Average annual rainfall at Waiouru (607m asl)

1081mm

Adiabatic Lapse Rate

Temperatures decrease by 1 degree for every 100m increase in altitude

Orographic Rainfall

Precipitation produced when moist air is lifted and cooled as it moves over a mountain range.

Westerly

Prevailing wind in Tongariro region

Climax vegetation

The final stage of vegetation succession attainable by a plant community in an area under the environmental conditions

Beech forests

Climax vegetation in Tongariro region

Where can beech forests be found in the Tongariro region?

Southwest slopes of Ruapehu

Pihanga

Snowline

The altitude above which there is a permanent layer of ice and snow

Treeline

The altitude above which trees cannot grow

Where is the snowline on Ruapehu?

2000m asl

Where is the treeline on Ruapehu?

1600m asl

Plants found between snowline and treeline

Alpine herbs

Mosses

Lichen

Matweed

Maximum altitude beech forests can be found on Ruapehu

1200m asl

Average temperature at base of Ruapehu

13 degrees

Average temperature 1200-1600m asl on Ruapehu

9-12 degrees

Average temperature 1600-2000m asl on Ruapehu

5-9 degrees

Average temperature above the snowline on Ruapehu

5 degrees

How does volcanism interrupt vegetation succession in the Tongariro region?

Ash showers and ignimbrite flows smother plants, while fires, lahars, mass movements, pyroclastic flows, lava flows, and debris avalanches destroy everything in their path.

Trellis drainage pattern

Contains right angles. Result from underground folding and faulting which influence drainage

Radial drainage pattern

Patterns occur on round cones or mountains

Dendritic drainage patterns

From tree-like pattern. Develop in broken hill country with no marked differences in rock hardness.

Aeolian erosion

Erosion by wind

Fluvial erosion

Erosion by running water

Frost heave

The uplift of soil or debris due to the expansion of groundwater upon freezing.

Frost shattering

The mechanical disintegration of rock by the pressure of water freezing in pores and along grain boundaries. Also called freeze-thaw

Mass movement

Bulk movements of soil, rock, or debris downhill due to the influence of gravity

Weathering

The process of being worn down by the environment. Includes mechanical and chemical weathering.

Glaciation

The process of being covered by glaciers

Firn

Snow that has been compacted but is not yet glacial ice

Neve

The partially compacted granular snow that forms the surface part of the upper end of a glacier

Cirque

A bowl or depression formed by glaciation

Arete

A sharp ridge, formed by glaciation

Plucking

Erosion caused by glaciers along the ground as they pull up pieces of rock

Abrasion

Erosion caused by glaciers along the valley walls as they grind off pieces of rock

Lateral moraine

Moraine along the sides of a glacier

Terminal moraine

Moraine at the end of a glacier

U-shaped valley

Steep, straight-sided valleys with a flat bottom, created by glaciers

V-shaped valley

Steep-sided valleys created by rivers

Accumulation zone

The high-altitude area of a glacier where accumulation and compaction of snow/ice takes place.

Ablation zone

The low-altitude area of a glacier where melting takes place

When did the last Ice Age begin?

100,000 ya

When did the last Ice Age end?

18,000 ya

Wind eddies

Circular current of air

Alpine saddle

Lowest point of a ridge between two peaks.

How do alpine saddles increase denudation?

Wind funnels through the saddle and increases in strength, increasing denudation

How does frost heave move debris downhill?

When occurring on a slope, the frost heave will push debris out perpendicular to the surface, but when the frost melts the debris will move downhill. This is an example of soil creep

Soil creep

Downward movement of soil due to gravity. Happens over a long period of time

How does high precipitation affect mass movement?

Mass movement can be accelerated when the ground is waterlogged. This can trigger landslides or increase the rate of soil creep.

Average annual rainfall in Rangipo Desert

1000mm

Average annual rainfall at Whakapapa Village (1119m asl)

2200mm