2. How are coastal landforms developed? Flashcards
(40 cards)
What are the main geomorphic processes shaping coastal landforms?
Weathering, mass movement, erosion (hydraulic action, abrasion, attrition, solution), transportation (traction, saltation, suspension, solution, longshore drift), and deposition.
What is the role of aeolian processes in coastal landscapes?
Aeolian (wind) processes transport and deposit sand, forming features like dunes and contributing to sediment budgets.
What landforms are predominantly formed by coastal erosion?
Cliffs, wave-cut platforms, geos, blowholes, caves, arches, stacks, and stumps.
How do caves, arches, stacks, and stumps form?
Erosion enlarges weaknesses in headlands to form caves; continued erosion breaks through to form arches; collapse of arches leaves stacks; further erosion reduces stacks to stumps.
What landforms are predominantly formed by coastal deposition?
Beaches, spits, onshore bars, tombolos, and salt marshes.
How does a spit form?
Longshore drift transports sediment along the coast; when the coastline changes direction, sediment is deposited, extending outwards to form a spit.
What are key features of the Saltburn to Flamborough Head coastline?
High-energy environment with resistant chalk and sandstone cliffs, prominent headlands and bays, and features like caves and stacks formed by erosion.
How do geological factors influence landforms here?
Variations in rock resistance lead to differential erosion, forming headlands and bays; faults and joints in the rock guide the development of erosional features.
What are key features of the Nile Delta?
Low-energy environment with extensive depositional features like beaches, spits, and lagoons; sediment supplied by the Nile River contributes to delta formation.
How has human activity affected the Nile Delta?
Construction of the Aswan High Dam reduced sediment supply, leading to increased coastal erosion and retreat of the delta coastline.
How are coastal landforms interrelated within a landscape system?
Landforms such as beaches, dunes, and spits interact through sediment transfer; changes in one can affect the development and stability of others.
Over what timescales do coastal landforms change?
Changes occur over various timescales—from rapid events like cliff collapses (seconds) to gradual processes like spit growth (millennia).
How do flows of energy and materials affect coastal landscapes?
Energy (from wind, waves, tides) drives geomorphic processes like erosion, transport, and deposition. Material (e.g. sediment) is moved and reshaped to form landforms.
What are the key geomorphic processes in coastal environments?
Weathering: Breakdown of rocks in situ (mechanical, chemical, biological).
Mass movement: Downslope movement (e.g. slumping, rockfall).
Erosion: Hydraulic action, abrasion, attrition, solution.
Transportation: Traction, saltation, suspension, solution.
Deposition: Sediment is laid down when energy decreases.
Aeolian processes: Wind transports and deposits dry sand, especially in dunes.
How do geos and blowholes form?
Erosion follows lines of weakness in rock (e.g. faults), forming narrow inlets (geos) and upward erosion through rock layers (blowholes).
What landforms and processes are found between Saltburn and Flamborough Head?
Landforms: Chalk cliffs, wave-cut platforms, caves, arches, stacks.
Processes: High wave energy, long fetch, hydraulic action and abrasion dominate.
Geology: Chalk is less resistant than hard sandstone; fault lines guide erosion.
Longshore drift: Moves sediment southwards, creating sediment cell dynamics.
How are coastal landforms interrelated?
Erosion at one point supplies sediment for deposition elsewhere. Beaches protect cliffs; removing sediment (e.g., from dredging) can increase erosion.
What physical factors influence landform development?
Winds (speed/direction)
Wave energy and direction
Tides and tidal range
Lithology (rock type and resistance)
Structure (bedding planes, faults, joints)
How and why do coastal landforms change over different timescales?
Seconds: Cliff collapse.
Seasons: Beach profiles change — steep in summer (constructive waves), flatter in winter (destructive waves).
Years to Millennia: Spit growth, delta building, or retreat due to sea level rise.
What is abrasion?
The scraping of pebbles on the land, wearing it away.
What is longshore drift?
The zig-zagging movement of waves, carrying sediment along the coast.
What is hydraulic action?
When waves push into cracks, compressing the air and causing high pressure. This widens the crack.
What is suspension?
When fine silts are carried by the flow of water.
What is a landslide?
When large areas of cliff collapse, often along a fault line or bedding plane.
