earth science

Submergent coastline

Submergent coastline is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Submergent coastline rather than just read about it. In short: Submergent coastlines or drowned coastlines are stretches along the coast that have been inundated by the sea by a relative rise in sea levels from either isostacy or eustacy. Submergent coastlines are the opposite of emergent coastlines, which have experienced a relative fall in sea levels.

Key takeaways

Submergent coastline belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Submergent coastline to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Submergent coastline from memory before moving on to harder problems.

Reference excerpt

Submergent coastlines or drowned coastlines are stretches along the coast that have been inundated by the sea by a relative rise in sea levels from either isostacy or eustacy. Submergent coastlines are the opposite of emergent coastlines, which have experienced a relative fall in sea levels. Many submergent coastlines were formed by the end of the Last Glacial Period (LGP), when glacial retreat caused both global sea level rise and also localised changes to land height.

Formation Submergent coastlines form either when sea level rises or the land level fall. This can be caused by isostatic or eustatic change. Both isostatic and eustatic change can be caused by a variety of reasons. Isostatic change could be due to post-glacial adjustment. Another common cause of isostatic change that can result in a submergent coastline is tectonic action. Events such as earthquakes or volcanic eruptions may cause land subsidence therefore causing isostatic sea level increases. Eustatic sea level rise can also be caused by many reasons. One common reason is thermal expansion. Thermal expansion occurs when water gets warmer and so the volume of water increases, this therefore causes global sea level rise forming submergent coastlines.

Common features Features of a submergent coastline include:

Rias

Rias, a drowned river valley. They are a section of a river valley flooded by the sea, making them much wider than would be expected based on the river flowing into it. Many rias were formed by the rise in sea level after the melting of vast continental glaciers. Rias commonly have a widening funnel shape and gradually increasing depth as they move towards the coast. The widening and deepening of the ria towards the sea usually causes an exaggerated tidal effect within the estuary.

Fjords Fjords, which are drowned glaciated valleys (Also known as U-shaped valleys). A section of a glacially eroded valley is flooded by the sea when a fjord is formed.

Dalmatian Coasts

Dalmatian coasts composed of long narrow islands running parallel to the coastline and separated from the coast by narrow sea channels called sounds. Dalmatian coasts are named after the Dalmatia region of Croatia which displays the common features of a dalmatian coast.

Examples Notable and illustrative examples of submergent coastlines include:

Western Norway, famed for its many fjords created by sea level rise at the end of the LGP. The Western Coastal Plains of the Indian subcontinent, which includes the estuaries of the Narmada and the Tapti Rivers. Southern England and South Wales, caused by a "see-saw" reaction to uplift to the north of Great Britain after glacial retreat redistributed weight on the land, including many substantial rias such as Falmouth Harbour, Plymouth Harbour, Kingsbridge Estuary and Milford Haven. The Dalmatian coast, famed for its many small inshore islands, formed by sea level rise in the Mediterranean at the end of the LGP. Port Jackson or the Sydney Harbour in New South Wales, Australia is an example of a ria or drowned river valley.

References

Illustrations

Worked examples

Example 1 — a first encounter with Submergent coastline

Start with the simplest possible case. Write down what Submergent coastline claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Submergent coastline before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Submergent coastline ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Submergent coastline

In research: Submergent coastline appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Submergent coastline in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Submergent coastline is common in secondary-school and first-year university syllabi. It links to neighbouring topics Coastal and oceanic landforms, Coastal geography, so understanding it makes those chapters shorter.
In everyday life: Look for Submergent coastline outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Submergent coastline in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Submergent coastline means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Submergent coastline out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Submergent coastline in simple terms?

Why does Submergent coastline matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Submergent coastline?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Submergent coastline.