Coasts EQ1

Lithology

The study of general physical characteristics of rocks.

Morphology

The study of the geological structure, shape or form or a feature.

What is the littoral zone?

Wider coastal zone, includes areas adjacent to the coast, as well as shallow parts of the sea just offshore.

Sub-aerial processes

Processes of weathering, mass movement and surface runoff occurring above the water line.

Coastal accretion

A continious net deposition of sediment.

Backshore

Area of the beach that extends from the limit of high water line to dunes. Only affected by waves in storms or huge high tide.

Foreshore

Part of the shore between high and low water marks, or between water and cultivated land.

Nearshore

Zone extending to the sea from the water line beyond the breaker zone, extends further than the littoral zone.

Offshore

The zone off the nearshore zone extending out to the sea.

Rocky coasts

Result from resistant geology, able to withstand the erosive forces of the sea. Often found in high energy environments.

Coastal plains

Found near areas of low relief and result from supply of sediment from offshore sources. Low-energy environments, include sandy and esturine coasts.

Submergent coast

Formed due to inundation by the sea and low sea levels. Dalmation coasts, fjords.

Emergent coast

Stretch of coastline exposed by receding sea levels. Haff coasts, raised beaches.

Wave refraction

Shallower water causes waves to slow and bunch up, growing in height and with a shorter wavelength. As waves approach the shore at an angle, they bend and change direction. Where the waves diverge, they lose power, dropping sediment to form beaches, leaving power to be concentrated on the headland.

Impact of wave refraction on bays

Sediment deposition as waves lose power. Waves reach shallower water later, no erosive power. Low energy waves. Velocity and wavelength decreases.

Impact of wave refraction on headlands

Concentration of wave energy. Erosion of headland cliffs. Formation of wave-cut platforms. Higher and steeper waves.

Concordant coastline

Geological rock strata runs parallel to the sea. Dalmation coastline, haff coasts.

Discordant coastline

Alternating bands of hard and soft, erodable rock meet the coastline at a right angle. Headland and bays. .g: holderness coast

Dalmation coasts

Result of sea level rising, with valleys and ridges running parallel. When valleys flooded, tops remain above sea level, forming islands. Found in Croatia.

Haff (lagoon) coasts

Spits of sand and lagoons are parallel to the coast. Sediment ridges with sand dune tops run parallel, creating haffs between the ridge and shore.

Strata

A layer or series of layers of rock in the ground.

Deformation

The degree which rock units have been deformed by tectonic activity.

Faults

Represent major weaknesses in rock layerse either side of fault line. Rocks heavily fractured are exploited by weaknesses.

Joints

Occur in most rocks, often in regular patterns dividing rock strata into blocks with a regular shape.

Fissures

Very small cracks representing weaknesses exploited by erosion.

Folding

Rock layers become permanently curved and bent due to horizontal compressional forces.

Crystalline

Structure and form of a crystal.

Lithification

Process in which sediment compacts under pressure, so it expels fluids and becomes solid rock.

Bedding planes

Lines between layers of strata of rock.

Micro features

Small-scale features such as caves, arches and wavecut notches.

Dip

Angle of inclination of the strata from horizontal.

Horizontal dip

A rock layer that is lying flat, with no tilt or slope, so that the layers of rock are horizontal rather than sloping.

Seaward dip, high angle

Dips gently seaward, resulting in a resistant cliff face being steep, but not overhanging.

Seaward dip, low angle

Overhanging rock, profile of 90 degrees, may cause rock falls.

Landward dip

Steep profile of 80 degrees, very stable and no rock falls.

Sedimentary rocks

Often folded and heavily fractured, weaknesses erosion can exploit. Weaker, clastic and erode faster. Sandstone, shale.

Igneous rocks

Rocks are crystalline, the interlocking crystals make rocks hard and erosion resistant. Have few joints, so limited weaknesses, erode very slowly. Granite, basalt.

Metamorphic rocks

Many metamorphic rocks exhibit a feature called foliation, where crystal are all orientated in one direction, producing weaknesses. Slow erosion rate. Marble, slate.

How do salt marshes form?

Form in an estuary, where fresh river water meets salty seawater and mix. This slower water deposits sediment, accumulating and forming mudflats. Particles clump together in flocculation, building the marsh. Salt-tolerant pioneer plants colonize the salt marsh, trapping further sediment. Mud level rises, mand develop a wider range of plants that are not adapted to salt conditions. Continues until meadow and new land created.

What is plant succession?

Directional change in the types of plant species occupying an area over time. Involves colonization, establishment and extinction.

What are halophytes?

Plants able to tolerate seawater either around their roots or being submerged.

What are xerophytes?

Able to tolerate very dry conditions, such as coastal sand dunes where soil retains little water.

Sand dune succession

Embryo dunes Fore dunes Yellow dunes Grey dunes Mature dunes

How do embryo dunes form?

Wind speeds slow and sand is deposited around an obstruction. Other vegetation are able to stabilise the dune, allowing it to grow.

How do fore dunes form?

Develop as more sand is accumulated and plants grow. Humus is added to the sand as plants decompose adding nutrients.

How do yellow dunes form?

Increased nutrients allow for a variety of plants to colonise yellow dunes. Become increasingly stable.

How do grey dunes form?

Covered in 100% vegetation and sand has now turned a brown colour with humus.

How do mature dunes form?

Develop fixed sand and have a nutrient content able to support vegetation such as oaks and birch. Nutrient rich brown soil.

What are dune slacks?

Depressions reaching down to the water table and seperate dunes.

What are blowouts?

Form when fragile sand dunes have vegetation cover destroyed by grazing animals or human activity.