Coastal Landforms Flashcards

All 12 cards in this deck

What is the difference between a discordant and a concordant coastline?

Discordant: bands of hard and soft rock meet the coast at right angles, giving headlands and bays. Concordant: the bands run parallel to the coast, giving a fairly straight coastline.

True or false? Chalk cliffs are eroded faster than boulder clay cliffs.

False. Chalk is a more resistant rock, so it erodes slowly and forms headlands; soft boulder clay (e.g. Holderness) erodes much faster.

How do headlands and bays form?
e.g. Swanage Bay and Durlston Head, Dorset

1. A discordant coastline has alternating bands of hard and soft rock at right angles to the sea.
2. The softer rock (clay/sand) is eroded faster to form a bay — Swanage Bay.
3. The more resistant rock is left jutting out as a headland — Durlston Head.

How does a cliff retreat and a wave cut platform form?
e.g. below the cliffs at Flamborough Head

1. Waves erode a wave cut notch at the base of the cliff between high and low tide.
2. The notch deepens until the overhanging rock collapses, so the cliff retreats inland.
3. The gently sloping rocky surface left behind, exposed at low tide, is the wave cut platform.

What is the sequence of formation of a stack?
e.g. Old Harry Rocks, Dorset

1. Hydraulic power and abrasion widen a crack in a headland into a cave.
2. The cave is eroded right through the headland to form an arch.
3. The arch roof collapses, leaving an isolated pillar — a stack, which later erodes to a stump.

How does a spit form?
e.g. Spurn Head, Holderness

1. Longshore drift transports sediment along the coast until the coastline changes direction.
2. Sediment is deposited in the sheltered, shallower water, building a ridge out to sea.
3. A change in wind or wave direction curves the end (recurved end); salt marsh forms behind it.

Which waves form a shingle beach and which form a sandy beach?

Shingle beaches (steep and narrow) are formed by high-energy destructive waves; sandy beaches (wide and gently sloping) are formed by low-energy constructive waves in sheltered bays.

What conditions are needed for sand dunes to form?

A large supply of dry sand, a large tidal range, strong onshore winds, and an obstacle (e.g. driftwood) to trap the sand; marram grass then stabilises it.

What is a bar, and what forms behind it?

A spit that has grown right across a bay, joining two headlands; the water trapped behind it becomes a lagoon.

Name three landforms that show, on a map or photograph, that a UK coastline is being eroded.

Any three of: cliffs, wave cut platform, caves, arches, stacks, stumps, headlands and bays.

Name two landforms of erosion and one landform of deposition found on the Dorset coast.

Erosion: Durdle Door (arch), Old Harry Rocks (stacks), Lulworth Cove (cove/bay). Deposition: Chesil Beach (tombolo/barrier beach) or the beach and dunes at Studland Bay.

True or false? A spit grows across a river mouth until it joins the land on the other side.

False. River flow keeps a channel open, so a spit stops short; a bar forms when a spit grows right across a bay.