HaSS Landforms and Landscapes

What are tectonic plates?

Large pieces of Earth's crust and upper mantle that move slowly over the softer mantle beneath them.

What is a divergent (constructive) plate boundary?

Two plates move apart. Magma rises into the gap, cools and forms new crust. This can create rift valleys on land and mid-ocean ridges underwater.

What happens at a convergent (destructive) plate boundary?

Two plates move towards each other. One plate may be forced beneath the other in subduction, causing earthquakes, volcanoes and mountains.

What happens when two continental plates converge?

Neither plate easily subducts because both are relatively buoyant, so the crust is compressed and pushed upwards, forming fold mountains.

What happens when an oceanic plate and continental plate converge?

The denser oceanic plate subducts beneath the continental plate. This can cause earthquakes, volcanoes and mountains.

What is a transform (conservative) plate boundary?

Two plates slide horizontally past each other. Crust is neither created nor destroyed. Friction can cause earthquakes.

What is weathering?

The breakdown of rock in place at or near Earth's surface. It does not involve the movement of the material.

What is physical weathering?

Rock is broken into smaller pieces without changing its chemical composition.

Examples of physical weathering:

• Freeze-thaw

• Heating and cooling

• Abrasion

• Pressure release/unloading

What is chemical weathering?

Rock is broken down because its minerals chemically react or change.

Examples of chemical weathering?

• Carbonation: rainwater reacts with rocks such as limestone.

• Oxidation: oxygen reacts with iron-containing minerals.

• Hydrolysis: water reacts with minerals and changes them.

What is biological weathering?

The breakdown of rock caused by living organisms.

Examples of biological weathering?

Plant roots growing into cracks, animals burrowing, and organisms such as lichens producing substances that weaken rock.

What is erosion?

The wearing away and movement of weathered rock and sediment from one place to another.

What are the four main agents of erosion?

🌊 Water
🌬 Wind
🧊 Ice/glaciers
🌊 Waves

What is the difference between weathering and erosion?

Weathering breaks rock down in place.
Erosion involves the movement of sediment.

What are geomorphic processes?

Natural processes that shape and change Earth's surface, such as weathering, erosion, transportation, deposition and tectonic activity.

How is a V-shaped valley formed?

A river erodes vertically into its channel, especially in its upper course. Weathering and mass movement widen the valley, producing a V shape.

How is a waterfall formed?

A river flows over layers of hard and soft rock. Softer rock erodes faster, creating a drop. Continued erosion causes the waterfall to retreat and can form a gorge.

How is a floodplain formed?

During floods, a river spreads over its valley and deposits sediment. Repeated flooding builds a flat area beside the river.

How is a delta formed?

A river slows down when it enters a lake or ocean and deposits sediment at its mouth, building a delta.

What is a moraine?

A deposit of rock and sediment transported by a glacier.

What is deposition?

The dropping or laying down of sediment when the transporting agent loses enough energy to carry it.

When does deposition occur?

When water, wind, ice or waves slow down or lose energy.

Where does deposition commonly occur in rivers?

Where the river becomes slower, such as the inside of meanders, floodplains and river mouths.

What is the general relationship between erosion and deposition?

Erosion removes material; deposition puts it down somewhere else.

How are volcanoes formed?

Magma rises through weaknesses or cracks in Earth's crust. When it reaches the surface, it erupts as lava, ash and gases. Repeated eruptions can build a volcano.

Where do volcanoes commonly form?

At convergent boundaries, where subduction causes melting, and at divergent boundaries, where magma rises as plates separate. They can also form over hotspots.

How does subduction cause volcanoes?

A dense oceanic plate sinks beneath another plate. Water and other materials released from the subducting plate help cause melting in the mantle, producing magma that can rise and erupt.

What is the difference between magma and lava?

Magma is molten rock below Earth's surface.
Lava is molten rock that has reached the surface.

How are earthquakes caused?

Stress builds up in Earth's crust as tectonic plates move. When rocks suddenly slip along a fault, stored energy is released as seismic waves, causing an earthquake.

What is a fault?

A fracture or crack in Earth's crust where movement can occur.

What are seismic waves?

Waves of energy released by an earthquake that travel through the Earth.

Where do earthquakes commonly occur?

Along tectonic plate boundaries, especially transform boundaries and convergent boundaries.

How do geomorphic processes work together?

Weathering breaks rocks down, erosion moves the material, transportation carries it, deposition drops it somewhere else, over time these processes create and change landforms.

Volcano

A landform where magma, ash and gases escape from inside Earth through an opening in the crust. Repeated eruptions can build a mountain around the opening.

Floodplain

A flat area of land beside a river that is regularly covered by water during floods. Flooding deposits fertile sediment.

Butte

A small, steep-sided, flat-topped hill left behind after erosion removes the surrounding rock.

Memory: Butte = small flat top.

Mesa

A larger, flat-topped, steep-sided area of high land. It is wider than a butte.

Memory: Mesa = medium/large flat top.

Plateau

A large area of high, relatively flat land. It can form through uplift or volcanic activity and can later be shaped by erosion.

Memory: Plateau = huge elevated flat area.

Lake

A large body of water surrounded by land, usually containing freshwater, although some lakes are salty.

Basin

A low area of land surrounded by higher land, where water and sediment can collect.

Canyon

A deep, narrow valley with steep sides, usually formed when a river erodes downward through rock over a long period.

Alluvial fan

A fan-shaped deposit of sediment that forms where a fast-flowing stream or river leaves a steep mountain area and suddenly slows down.

Strait

A narrow body of water that connects two larger bodies of water.

Cape

A point of land that sticks out into a body of water.

Island

An area of land completely surrounded by water.

Archipelago

A group or chain of islands.

Sound

A large, relatively sheltered body of water, often partly enclosed by land or islands and connected to the sea.

Peninsula

An area of land almost completely surrounded by water, but still connected to the mainland.

Memory: Peninsula = island with a land connection.

Harbour

A sheltered area of water along a coast where ships and boats can safely anchor.

Isthmus

A narrow strip of land connecting two larger areas of land, with water on both sides.

Memory: Peninsula = water around 3 sides.
Isthmus = land connecting 2 bigger land areas.

River mouth

The place where a river flows into another body of water, such as an ocean, sea or lake.

Delta

A deposit of sediment at the mouth of a river, often creating new land with smaller channels branching through it.

Barrier / sand bar

A ridge or bank of sand or sediment deposited by waves and currents, often running parallel to a coastline or partly blocking a bay or river mouth.

Plain

A large area of mostly flat or gently rolling land, usually at relatively low elevation.

Gulf

A large area of ocean or sea that extends into the land and is partly surrounded by land.

Tributary

A smaller river or stream that flows into a larger river.

Memory: Tributary = side river joining the main river.

River valley

A long, low area of land between higher areas, formed and shaped by a river's erosion.

Divide

A ridge or high area of land separating two drainage basins. Rain falling on opposite sides flows into different river systems.

River source

The place where a river begins, often in mountains, hills, glaciers, springs or lakes.

Moraine

A pile or ridge of rocks and sediment deposited by a glacier.

Glacier

A large, slow-moving mass of ice formed from compacted snow that moves downhill under gravity.

Mountain

A large, steep area of land that rises significantly above the surrounding landscape. Mountains can form through tectonic uplift, volcanic activity or other geological processes.