Landform Detective: Coasts

The coast that keeps losing villages

The Holderness coast runs about 61 km down the Yorkshire coast from Flamborough Head to Spurn Point, and it is the fastest eroding coastline in Europe. The long-term average retreat is around 1.8 m a year, and in places it has been considerably more. Since Roman times something like 4 km of land has gone and at least 29 villages named in medieval records have disappeared into the North Sea altogether. Travel a few miles north to Flamborough Head and the cliffs have barely moved. The same North Sea, the same storms driven by the same long fetch, and an almost completely different result. The difference is the rock. Flamborough is chalk, resistant enough to stand as a headland with caves and arches cut into it. Holderness is boulder clay, glacial till dumped as the last ice sheets melted, so weak that a wave can undercut it and a whole face slumps into the water. That single contrast is the key to the entire topic. Where a coast has bands of different rock meeting the sea, the tough bands stand out as headlands and the weak ones are cut back into bays. Where material is carried along a coast and then finds somewhere to settle, it builds beaches and spits, and the clay lost from Holderness is exactly what has built Spurn Head, a spit roughly 5.5 km long at the southern end. This module is about reading those shapes, and about telling each one as a sequence of events rather than describing a photograph.

Five coastal terms

The first two explain where landforms appear, the third and fourth are the classic erosional and depositional examples, and the fifth is why a spit ends up curved.

Sequence the stack

These six stages turn a crack in a headland into a stump. Put them in order.

• Waves attack a line of weakness in the rock of a headland
• The weakness is widened and deepened into a hollow cut back into the rock
• The hollow is driven right through to the other side, leaving a bridge of rock above
• The roof of the bridge is undercut until it can no longer support its own weight, and falls
• An isolated pillar is left standing in the water, detached from the headland
• That pillar is undercut in its turn until only a low remnant is left, covered at high tide

Why do headlands and bays form?

A stretch of coast has alternating headlands and bays. Which answer explains why?

• The rock reaching the shore is not uniform: where softer and tougher bands alternate along it, the softer ones give way first and are hollowed into bays while the tougher ones are left jutting out as headlands. Once the shape exists it maintains itself through wave refraction: waves bend around the headlands so their energy is concentrated there, while in the bays the same waves arrive spread out and weakened, which allows material to be deposited and a beach to build.
• Waves are simply stronger in some places along the coast than others.
• Headlands are built up by deposition while bays are eroded away.
• The tide reaches further up the coast in some places than others.

Two families of landform

Every coastal landform is either something the sea has taken away or something it has put down, and the named examples below are the ones worth carrying into an exam. Note the link at the foot of the columns: on Holderness the two families are the same material at two ends of one journey.

Find the landform built across the channel

The image shows a stretch of coast from above, with open water at the top and land along the bottom. The arrow shows the direction in which material is carried along the coast. Tap the landform that has been built by deposition where that material reached the mouth of a channel.

Match each shape to its story

Tell it as a sequence

The specification note for this topic names one requirement above all: formation must be given as a process, not as a description. The commonest weak answer describes what a landform looks like now and awards itself no marks. An examiner asking how a stack forms wants a sequence of events in order, each one causing the next. A reliable structure is to begin with the weakness, follow the widening, reach the moment of collapse, and finish with what is left. Use link words at every joint, since they are where the marks actually sit: because, this is widened until, eventually, which leaves. If your sentences could be shuffled without the answer getting worse, you have written a description. Two further habits. Start with the rock. Almost every coastal landform question is really a question about resistance, so saying what the cliff is made of and why that matters usually opens the answer well and earns credit immediately. And name real places. A stack is a stack, but a named headland with a named stretch of coastline attached to it is what turns a generic answer into a case study one. On command words: "describe the characteristics" wants the appearance and no causes, which is the one time description is what is being asked for. "Explain the formation" wants the sequence. "Suggest how" invites you to apply the sequence to an unfamiliar photograph or map, which is exactly what the skills questions do.

Complete the coastal landform facts

The Holderness coast retreats by an average of about _____ m a year, the fastest in Europe, because its cliffs are made of soft glacial boulder _____ rather than resistant rock. A few miles north, the chalk of Flamborough Head stands out as a headland, and waves bend around it through wave _____ so that their energy is concentrated there and spread thinly in the bays between. A crack in such a headland is widened into a cave, driven through into an arch, and when the roof collapses an isolated _____ is left standing in the water. Material eroded from Holderness travels south and has built Spurn Head, a _____ roughly 5.5 km long.

Spot the three accurate coastal claims

Select the THREE statements that are true.

• On Holderness the erosion and the deposition are two ends of one process, because the boulder clay lost from the cliffs further north is the material that has built the spit at the southern end.
• Headlands are attacked hardest even though they are made of the most resistant rock, because waves bend around them and concentrate their energy there while arriving spread out and weakened in the bays.
• A wave-cut platform is what is left behind as a cliff retreats, exposed at low tide, after repeated undercutting at the base and collapse of the overhang above.
• Headlands are formed by material being deposited and built up where the coast projects furthest.
• Holderness erodes so fast because the waves there are far more powerful than anywhere else in Britain.
• Describing what a stack looks like is enough to answer a question on how one forms.

A 6-mark formation answer, marked

Explain the formation of a wave-cut platform. [6 marks] A wave-cut platform forms where waves are attacking a cliff of rock weak enough to be worn back, such as the boulder clay of the Holderness coast, where retreat averages around 1.8 m a year. Waves concentrate their attack between the high and low water marks, so a notch is cut into the base of the cliff rather than the whole face being worn evenly. Because that notch deepens over time, the rock above it is left overhanging with progressively less beneath to support it, and eventually the overhang cannot carry its own weight and collapses onto the shore. This leaves a fresh cliff face slightly further inland than the old one, and the debris that has fallen is broken up and carried away, so the waves begin cutting a new notch at the base of the new face. As this cycle repeats, the cliff line steps steadily backwards and the rock that used to lie beneath it is left behind as a gently sloping surface running out to sea, exposed at low tide and covered again at high tide. The platform is therefore not something the sea has built but the stub of everything the sea has removed, which is why its width is a record of how far the cliff has travelled. What earned the marks: a sequence in order with each stage caused by the last, carried by link phrases rather than listed; the notch, the overhang, the collapse and the repetition all present; a named coastline with a figure attached; and a closing sentence that says what the landform actually is, which is a remnant rather than a construction.

Find the two sentences that explain

Five sentences from an answer about how a stack forms. Three of them only describe what can be seen. Tap the TWO that give a stage of the process and its cause.

• Waves attack a line of weakness in the rock, and because that weakness offers least resistance it is widened into a hollow cut back into the headland.
• The stack stands several metres tall in the water off the end of the headland.
• The roof of the arch is undercut until there is too little rock beneath it to carry its weight, and it collapses, leaving the far side standing alone.
• The rock is white chalk and seabirds nest on the ledges.
• At high tide the base of the stack is surrounded by water.

Build the headland sentence

Assemble a sentence that explains a headland rather than describing it.

Four shapes on a map

You are given an unfamiliar stretch of coast. Work out what each feature is and how it got there.

• The coastline alternates between projecting points and curved inlets. A geology map shows bands of chalk and clay meeting the sea at an angle.
• A narrow ridge of shingle extends from the land out across a river mouth, hooking back at its far end, with mudflats and salt marsh in the sheltered water behind it.
• A photograph shows a pillar of rock standing in the sea just beyond the tip of a headland, with a natural bridge of rock still visible closer in.
• Two stretches of the same coast, exposed to the same North Sea storms, are retreating at wildly different rates. One has lost villages; the other has barely changed in centuries.

Explain a formation

Explain the formation of a spit, and explain why the coastline it forms on is also losing land rapidly. [9 marks]

• Source of material and the process moving it along the coast
• Link phrases are where the marks sit
• A figure for the rate of retreat
• On a coast like Holderness, material lost from the cliffs builds the spit