Fjord

Geography glossary

Also called: Fiord · Topic: Landforms and their Evolution: Rivers, Groundwater, Glaciers, Waves and Wind · NCERT: Class 9, Ch 2 "Shaping of the Earth's Surface"; Class 11, Ch 6 "Landforms and their Evolution"

Meaning

A fjord (also spelt fiord) is a long, narrow, steep-sided arm of the sea. It forms when a very deep glacial trough (a U-shaped valley cut by a glacier) is drowned by the sea. Fjords matter because they show where thick glaciers once reached the coast. Their deep, sheltered water also makes them good natural harbours, as in Norway (NCERT Class 9).

Explanation

How a fjord forms (cause → process → result)

  • Cause: a glacier reaches the coast
  • In high latitudes during the Ice Age, valley glaciers flowed all the way down to the sea.

  • These glaciers were very thick, and their sheer weight pressed hard on the rock.

  • Process: the glacier digs a deep trough

  • Plucking (quarrying): meltwater seeps into joints (cracks) in the bedrock and freezes onto the rock. The moving ice then pulls out angular blocks.
  • Abrasion: the blocks frozen into the base and sides of the ice scrape the valley like sandpaper. This leaves the rock smooth and scratched with glacial striations (parallel grooves that show which way the ice moved).
  • The glacier fills the whole valley. It widens and deepens the valley evenly and cuts off the spurs that stick out.

  • Near the coast the ice was thick enough to cut the valley floor far below today's sea level.

  • Result: the sea floods the trough

  • The ice later melted and sea level rose.
  • Seawater moved into the empty trough. It became a long, deep, narrow inlet with steep walls.

Shape and parts of a fjord

  • Cross-section: U-shaped, with steep, smooth, cliff-like sides and a broad, deep floor below the water.
  • Length and course: long, narrow and fairly straight. It runs far inland from the open sea.
  • Depth: very deep. It is often deeper inland than near its mouth, because the ice eroded most strongly where it was thickest. A shallower rock bar (sill) often lies near the mouth.
  • Side features: the side walls often show the same features as a glacial valley on land:
  • Hanging valleys: side valleys left high above the main trough. Their streams fall into the fjord as waterfalls.
  • Truncated spurs: ridges cut back by the main glacier into steep triangular facets.

Conditions needed

  • High latitude or very cold climate: glaciers must have been big enough to reach the coast.
  • Mountainous coast: the land must be high, with valleys for glaciers to flow down.
  • Later rise in sea level: the trough has to be drowned. Without the sea it stays a dry U-shaped valley.

Where it occurs

  • Norway: the Sognefjord, at about 61°N, is the longest and deepest fjord in Norway. Norway's coast is the classic fjord coast.
  • Greenland: a fjord coast around a land still covered by an ice sheet (continental glacier).
  • Southern Chile: fjords along the southern Andes coast.
  • New Zealand: Fiordland, in the south-west of the South Island.
  • Alaska (USA) and British Columbia (Canada): fjords along the mountainous Pacific coast of North America.
  • India: India has no fjords. Its coasts lie in low (tropical) latitudes, where glaciers never reached the sea. Glaciers in India stay high in the Himalaya. They carve U-shaped valleys on land, as in Himachal Pradesh and Kashmir, but these valleys are not drowned by the sea.

Don't confuse with

  • Ria: a river valley (V-shaped) drowned by the sea. It gets shallower as you go inland. A fjord is a drowned glacial (U-shaped) trough with steep walls, and it is often deepest inland.
  • U-shaped valley (glacial trough): the same landform, but on land and not drowned. It becomes a fjord only when the sea floods it.
  • V-shaped valley: cut by a river, with a narrow floor and interlocking spurs. A fjord comes from glacial erosion, never from river erosion.
  • Estuary: the wide mouth of a river where fresh water mixes with seawater. It is shaped by the river and tides, not by ice.

Prelims Hooks

  • Fjord = a glacial trough drowned by the sea. It is an erosional landform of glaciers, not a depositional one.
  • Feature–country pairs: Sognefjord–Norway (the longest and deepest in Norway, about 61°N). Fiordland–New Zealand (South Island).
  • Other fjord coasts: southern Chile, Greenland, Alaska and British Columbia. All are high-latitude coasts.
  • Trap: a fjord comes from glaciers (U-shaped). A ria comes from a river valley (V-shaped). Both are drowned by the sea.
  • Process pair: plucking (pulling out blocks along joints) and abrasion (scraping and polishing) deepen the trough. A rise in sea level later floods it.
  • India has no fjords. Its glaciers stay in the high Himalaya and never reach the coast.

Mains Points

  • Fjords as an economic resource (GS-I, human geography):
  • Deep, sheltered water makes fjords good natural harbours, as in Norway (NCERT Class 9).
  • This has helped fishing, shipping and port towns grow on cold, mountainous coasts where flat land is scarce.

  • Hanging valleys that fall into fjords as waterfalls are useful sites for hydropower.

  • Fjords as evidence of past climate (GS-I, physical geography):

  • Fjords show that much larger glaciers once reached the sea in high latitudes.
  • When that ice melted, sea level rose and the troughs were drowned.

  • This makes fjord coasts a clear record of glaciation followed by a rise in sea level. It links landforms to climate change.

  • Effect on settlement and transport:

  • Steep fjord walls leave very little flat land, so settlements cluster at the heads and edges of fjords.
  • Fjords cut deep into the coast, so roads must make long detours. Ferries and sea routes therefore matter a lot for transport.

Related concepts

Read more

Sources

  1. 1Class 9, Ch 2 "Shaping of the Earth's Surface"; Class 11, Ch 6 "Landforms and their Evolution" (primary)