Q1: How and Why are coasts different?

LITTORAL ZONE: [land to sea] Backshore (highest sea level line), Foreshore, Nearshore, Backshore (base of wave first encounters friction with bed). 

Place of dynamic equilibrium: Inputs of sediment, constructive/destructive waves causing deposition/eroision, longshore drift, weathering and mass movements on backshore etc... 

Rapid change when increased energy, careless human activities etc 

CLASSIFICATION: variety of criteria e.g. geology, sea-level/land rise and fall (long term changes) erosion and deposition (short term changes). Either advancing or retreating 

High and low energy coasts: 

• Rocky coasts in high-energy coastal environment. Destructive waves, long fetches, erosion, sediments from eroded land, mass movement etc,  cliffs, wave-cut platforms
• Coastal plain landscapes in low-energy environments. Constuctive waves, shorter fetches, deposition, sediment from rivers, longshore drift, beaches, spits, bars, sheltered, lowland coasts e.g. Mediterranean sea coasts

Shape of coast largely determined by geology (resistance to erosion/weathering, consolidation) 

CONCORDANT: Rocks arranged in parallel to the coastline, alternating hard and soft

DISCORDANT: Rocks perpendicular to the coastline, often forming bays and headlands E.g. Lulworth coast, Devon 

Coastal morphology:

Headlands and bays form at discordant coasts, shape of coast causes waves to refract, concentrating energy on headlands, increasing rate of erosion

Haff coastlines and dalmation coasts form in low energy environments. 

Haff coasts: large lagoon found behind deposits of mud and sands parallel to shoreline e.g. Baltic coastline, Vistula Haff 91km long behind Vistula spit

Dalmation coasts: Valleys parallel to coasts flooded by sea level change E.g. Croatia 

JOINTING: Cracks where there is no movement of rock, often caused by cooling, tension, unloading weight from above

DIPPING: Rock and bedding planes (seperates layers of sedimentary rock) are at an angle from the horizontal

FAULTING: Cracks where there is movement of rock, often larger than joints, often caused by tectonic movements

FOLDING: Bending of rocks due to compressional forces. Upfold= anticline, Downfold= syncline

This all has important influences on coastal morphology, erosion rates, the formation of cliff profiles and occurrence of micro features

e.g. caves, blowholes, geos. A weak point will be weathered/eroded, that joint is then enlarged, may become large enough to form a cave

LITHOLOGY: rocks that make up base of land.

Igneous (made of cooled magmas e.g. granite) more resistant than Sedimentary rocks (made under oceans e.g. limestone). Metamorphic rocks (formed from igneous and sedimentary rocks under intense heat and pressure e.g. marble) are most resistant.

DIFFERENTIAL EROSION: Permeable rocks e.g. limestone (lots of joints and bedding planes), chalk (porous) allow water to pass through them.

Impermeable rocks e.g. granite do not let water in 

Water may affect sub-aerial processes (weathering and mass movement), if porous rock is above impermeable rock water will collect in upper layer causing slipping and slumping

Some rocks vulnerable to chemical weathering. Limestone soluble in rainater, becomes carbonic acid, absorbing carbon dioxide from air. Limestone contains calcium carbonate, dissolves into calcium bicarbonate which is carried away in solution. Sea water also absorbs carbon dioxide and dissolves limestone creating small pits.  

-Important for stabilising soft sediment low-energy coastlines.

SAND DUNE SUCCESSION: 

Pioneer plants e.g. sea rocket, colonising base areas first. They change the conditions by adding humus (decayed vegetation), retaining moisture and stabilising loose sand, creating more fertile growing conditions. Yellow dunes form a ridge near dune front, grow marram grass, colonises the dunes and they begin to go grey (higher humus content). Taller and more complex plants then able to grow e.g. Moorland heathers, plants from earlier stages die out unable to compete for light/water. Then pine or oak forests grow

SALT MARSH SUCCESSION: 

In sheltered bays where depostion occurs, salt and fresh water meet, low-energy environment

Mud flats develop, salt tolerant plants e.g. eelgrass begins to colonise/stabilise them. Halophytic plants e.g. Cordgrass grow, help slow down tidal flow and trap mud and silt (helps build it to higher level. As sediment accumulates, surface becomes drier and different plants begin to colonise e.g. Salt grass