Geography · Year 12 · Coastal Landscapes and Systems · Autumn Term

Emergent and Submergent Coastlines

Examine the landforms associated with rising and falling sea levels, such as raised beaches and rias.

• National Curriculum Attainment Targets
• A-Level: Geography - Coastal Landscapes and Change
• A-Level: Geography - Physical Systems and Processes

About This Topic

Emergent coastlines are formed when the land rises relative to sea level, or when sea level falls. This process exposes former sea floors, creating features like raised beaches, marine terraces, and wave-cut platforms that are now inland. Raised beaches are particularly compelling evidence, appearing as flat areas of sand or shingle above the current high tide mark, often backed by a cliff. These landforms are direct indicators of past sea level positions and geological uplift or isostatic rebound.

Conversely, submergent coastlines occur when sea levels rise relative to the land, or when the land sinks. This inundates existing river valleys and glacial troughs, forming distinctive features such as rias (drowned river valleys) and fjords (drowned glacial valleys). These coastlines are characterized by irregular shorelines with deep indentations and often offshore islands. Studying both emergent and submergent coastlines provides a comprehensive understanding of dynamic coastal geomorphology and the impact of sea level fluctuations.

Active learning is crucial for understanding emergent and submergent coastlines because it allows students to visualize and interpret complex geological processes and evidence. Hands-on map analysis and field trip simulations enable students to identify and classify landforms, fostering critical thinking and spatial reasoning skills.

Key Questions

1. Explain the formation of emergent landforms like raised beaches and marine terraces.
2. Analyze how submergent coastlines, such as rias and fjords, are created.
3. Compare the geological evidence for past sea level changes on different coastlines.

Watch Out for These Misconceptions

Common Misconception

Coastlines are static and unchanging.

What to Teach Instead

Students often perceive coastlines as fixed. Active learning, such as simulating sea level changes or analyzing sequential maps, demonstrates the dynamic nature of coastlines and the ongoing processes that shape them over geological time.

Common Misconception

Raised beaches are simply beaches that are now further inland due to erosion.

What to Teach Instead

The key difference is sea level change. Through examining geological cross-sections or analyzing landform profiles on maps, students can understand that raised beaches indicate a former sea level position, not just erosion pushing the shoreline back.

Active Learning Ideas

Map Analysis: Identifying Coastal Features

Provide students with detailed Ordnance Survey maps of various UK coastal areas known for emergent or submergent features. Students work in small groups to identify and annotate raised beaches, marine terraces, rias, and fjords, using map keys and topographical contours.

60 min·Small Groups

Coastal Process Simulation

Using a large tray with sand and water, students can simulate sea level rise and fall. They can build initial landforms, then introduce changes to the water level to observe the creation of emergent and submergent features, documenting the process with photographs or sketches.

45 min·Small Groups

Comparative Case Study Research

Assign pairs of students different UK coastlines (e.g., parts of Scotland for fjords, parts of the south coast for raised beaches). They research the specific geological history and landforms, then present their findings comparing emergent and submergent characteristics.

75 min·Pairs

Frequently Asked Questions

What is the difference between emergent and submergent coastlines?

Emergent coastlines form when sea levels fall or land rises, exposing former sea floor and creating features like raised beaches. Submergent coastlines form when sea levels rise or land sinks, flooding existing valleys and creating features such as rias and fjords.

How can students visualize the formation of rias and fjords?

Visual aids like animated diagrams or 3D models are effective. Students can also create their own physical models by carving river valleys or glacial troughs into clay or sand, then simulating a sea level rise to see how these features become inundated.

What geological evidence supports past sea level changes?

Key evidence includes raised beaches, marine terraces, submerged forests, and the characteristic shapes of rias and fjords. Analyzing the stratigraphy of coastal deposits and dating techniques like radiocarbon dating also provide crucial data.

How does active learning enhance understanding of coastal landforms?

Active learning, through map interpretation exercises or physical simulations, allows students to directly engage with the processes and evidence of coastal change. This hands-on approach helps solidify abstract concepts like sea level fluctuation and geological uplift, making the formation of emergent and submergent features more tangible and memorable.