Geography-Rivers

Where does a river usually begin?

In the mountains or hills (called the source).

What is a small river that flows into a bigger one called?

A tributary.

What do we call it when a river drops the materials it carries?

Deposition.

What is the end of a river called?

The mouth.

What landform is made by sediments at the river's mouth?

A delta.

Which part of a river is the fastest and steepest?

The upper course.

What do you call a curve or bend in a river?

A meander.

Name 3 ways rivers help people.

Farming, transport, and energy (also drinking water and fishing).

What forms when a meander is cut off?

An oxbow lake.

What’s it called when two rivers meet?

A confluence.

What are the four main types of river erosion?

Hydraulic action, abrasion, attrition, and solution.

How does a waterfall form in a river’s upper course?

From erosion of softer rock beneath harder rock, causing the harder rock to collapse.

What is a floodplain and how is it formed?

A flat area next to a river that floods; formed by repeated deposition of sediment.

Why does a river deposit more material in the lower course?

Because it slows down and loses energy.

How do meanders become oxbow lakes?

The neck of a meander narrows due to erosion and is eventually cut off during a flood.

What is a levee and how does it form?

A raised bank along a river, formed by sediment deposited during floods.

What is the difference between vertical and lateral erosion?

Vertical erosion deepens the riverbed; lateral erosion widens the riverbanks

Name and explain the four transportation processes in rivers.

• Traction – large rocks rolled along the bottom

• Saltation – small pebbles bounced

• Suspension – fine material carried in the water

• Solution – minerals dissolved in water

Why do deltas form at river mouths?

Because river loses speed and drops sediment faster than the sea can remove it.

What human activities can affect river systems?

Deforestation, dam construction, urban development, pollution, and farming.

What kind of erosion mainly happens in the upper course?

Vertical erosion — it cuts deep into the landscape, forming steep valleys.

What landform is created by vertical erosion in the upper course?

A V-shaped valley.

What is an interlocking spur?

Ridges of land that the river winds around in a V-shaped valley.

How are interlocking spurs formed?

The river erodes downwards and weaves around harder rock.

What causes waterfalls in the upper course?

Layers of hard rock over soft rock — soft rock erodes quicker, creating a drop.

What is a plunge pool?

A deep hole at the base of a waterfall, formed by the force of falling water and erosion.

What happens to a waterfall over time?

It retreats upstream, leaving behind a gorge.

What is a gorge?

A steep-sided valley formed as a waterfall erodes backward over time.

Why is discharge low in the upper course?

Because rivers are just beginning — small streams with less collected water.

What is the riverbed like in the upper course?

Rocky, uneven, and full of large boulders.

What type of erosion becomes more dominant in the middle course?

Lateral erosion — it erodes sideways, widening the river.

What is a meander?

A big curve or bend in a river, caused by both erosion and deposition.

Where does erosion happen in a meander?

On the outer bend — faster flow erodes the bank.

Where does deposition happen in a meander?

On the inner bend — slower flow drops sediment.

What is the river valley like in the middle course?

Wider and flatter compared to the steep, narrow upper course.

What is a river cliff?

A steep outer bank of a meander, created by erosion.

What is a slip-off slope?

A gentle inner bank of a meander, built by deposition.

How does the river's load change in the middle course?

Material is smaller and smoother from earlier erosion and transport.

Why does the river get wider and deeper in the middle course?

Because of increased volume, lateral erosion, and more tributaries joining.

What is the river’s speed like in the middle course?

Faster than the upper course, but not at its maximum yet.

What’s the main process happening in the lower course?

Deposition — the river slows down and drops its load.

Why does the river slow down in the lower course?

Because the gradient is flatter and the river is wide and deep.

What is a floodplain?

Flat land on either side of a river that gets covered when it floods.

How are floodplains formed?

By deposition during floods and lateral erosion over time.

What are levees?

Natural embankments formed from sediment left after floods.

What is an estuary?

A wide mouth of a river where fresh water mixes with sea water.

What is a delta?

A landform of deposited sediment where the river meets the sea and splits into channels.

Why do rivers form deltas in the lower course?

Because the flow slows and can’t carry its load anymore.

What is the sediment like in the lower course?

Fine, smooth, and very small — mostly silt and clay.

What happens to the meanders in the lower course?

They become wider and more exaggerated, sometimes turning into oxbow lakes.