The Coastal Zone Flashcards
Littoral Zone
The wider coastal zone including adjacent areas and shallow parts of the sea just offshore
When is the back shore affected by waves?
During exceptionally high tides or major storms
What is mainly confined to the foreshore?
Wave processes
What happens in the nearshore?
Intense human activity and forms part of the physical system, transfers sediments by currents close to the shore
What are the 2 main types of coast?
Rocky and Coastal Plains
Rocky Coastline
Have cliffs varying in height, formed from rock of varying hardness
Coast Plains
Land gradually slopes towards the sea, across an area of deposited sediment. Sand dunes and mud flats main examples.
Features of a cliffed coast
Transition from land to sea is abrupt, low tide reveals a rocky, wave cut platform foreshore.
Features of a sandy coastline
At high tide, sandy beach inundated, vegetated dunes are not. Vegetation on dunes stabilises coasts and prevents erosion.
Features of Estuarine coastlines
Mud flats, exposed at high tides, back shore vegetated and forms a salt marsh, gradual transition from land to sea.
What classifies as a primary coast?
Coasts dominated by land based processes like deposition at the coast or new coastal land formed from lava flows
What classifies as a secondary coast?
Coasts dominated by marine erosion or deposition processes
Emergent Coasts Features
Coasts rising relative to sea level, for example by tectonic uplift.
Submergent Coast features
Coasts flooded by the sea caused by rising sea levels.
How can coast classification vary due to tidal range?
Microtidal coasts - 0-2m
Mesotidal coasts - 2-4m
Macrotidal coasts - >4m
High Energy Coastlines features
Exposed coasts, facing prevailing winds, long wave fetches, powerful waves. More erosion than deposition, Headlands, Bays, wave cut platforms.
Low energy Coastline Features
Sheltered coasts with limited fetch, more depositon than erosion, beaches, spits, low wind speeds, small waves.
Cliff profile
The height and angle of a cliff, as well as its features, such as wave cut notches or changes in slope angle.
Marine erosion dominated cliff features
Steep angle cliff face, limited debris at its base as this is quickly eroded and moved away by waves and wave erosion, active undercutting
Sub aerial process dominated cliff features
curved slope profile, accumulated debris due to lack of erosion
Sub aerial processes
Processes acting on cliffs other than wave erosion. Likely to be more important when cliffs are made of less resistant rocks such as shale, clay or mud stone
Mass movement
Sub aerial process, includes landslides, slumps, rock fall, move material down slope under the influence of gravity
Weathering
Sub aerial process, chemical, biological, mechanical weathering. Breakdown of rock into smaller fragments
Surface runoff
Sub aerial process, Water, usually during heavy rain, flowing down the cliff face and causing erosion of it
How are coastal plains formed?
As a result of a fall in sea level, where the sea bed of what was once a continental shelf sea is exposed. Or can form from deposition of sediment from land, which can cause coastal accretion where the coastline gradually moves seaward.
Coastal Accretion
The deposition of sediment at the coast and the seaward growth of the coastline, creating new land. Involves sediment deposition being stabilised by vegetation.
Dynamic Equilibrium
The balanced state of a system where inputs and outputs balance over time. By a process of feedback, the system adjusts to change and the equilibrium is regained.
