Coasts Flashcards
What is a littoral zone?
A littoral zone is the wider coastal zone including adjacent land areas and shallow parts of the sea just offshore.
What is back shore?
Above high tide level and only affected by waves during exceptionally high tides and major storms.
What is nearshore?
Shallow water areas close to land and used extensively for fishing, coastal trade and leisure.
What is offshore?
The open sea.
What is the sediment supply?
The process of weathering and erosion produce sediment which is transported and deposited to produce coastal landforms.
What can sediment supply come from?
- Tidal currents
- Rivers discharge
- Coastal erosion
What is geology?
Geology is the physical structure and arrangement of a rock.
CLASSIFICATION OF COASTS.
Rocky vs coastal plains. Describe rocky coasts.
- Rocky coasts can have high or low relief
- Results from resistant geology (hard rocks)
- Often in a high energy environment (destructive waves). e.g. Galicia
CLASSIFICATION OF COASTS.
Rocky vs coastal plains.
Describe coastal plains.
- Referred to as ALLUVIAL coasts
- Sandy + estuarine coasts (found at the mouth of the river)
- Found near areas of low relief. e.g Sancti Petri
CLASSIFICATION OF COASTS.
Formation processes (primary coasts vs secondary coasts).
Describe primary coasts.
-Dominated by land-based processes —> as deposition at the coast from rivers/new coastal land formed from lava flow. e.g canary island (Volcanic activity)
CLASSIFICATION OF COASTS.
Formation processes (primary coasts vs secondary coasts).
describe secondary coasts.
-Are dominated by marine erosion or depositional processes. e.g canary island (volcanic activity)
CLASSIFICATION OF COASTS.
Geology.
What are the three types of rocks?
Igneous:
- Magma cools down in volcano (intrusive)
- In the Earth’s surface (extrusive)
e. g. Granite, Basalt (Canary island)
Sedimentary:
- Layers of sediment
e. g. limestone, sandstone (Mediterranean)
Metamorphic:
- Heat + pressure exerted onto sedimentary rock + change characteristics.
e. g. Marble, slate (West coasts of Ireland)
CLASSIFICATION OF COASTS.
Sea level change.
Emergent coasts:
- Where coasts are rising relative to sea level, due to tectonic uplift or glacier activity
e. g. Iceland, Hawaii
Submergent coasts:
- Are being flooded by the sea, either due to rising sea level and/or subsiding land.
e. g. Maldives, Bangladesh
CLASSIFICATION OF COASTS.
Tidal range.
3 types of tidal ranges.
- Micro-tidal coasts: tidal range of 0-2m
e. g. Mediterranean coasts - Meso-tadial: Tidal range of 2-4m
e. g. Indian Ocean, South East Asia - Macro-tidal: range greater than 4m.
e. g. Atlantic Ocean
CLASSIFICATION OF COASTS.
Wave energy.
2 types.
Low energy:
- Sheltered coasts with limited fetch and low wind speeds which result in small waves.
e. g. Mediterranean coasts
High energy:
- Exposed coasts, facing prevailing winds with long wave fetches which result in powerful waves.
e. g. Comillas, Galicia
When do destructive plate boundaries occur?
Destructive plate boundaries occur when oceanic & continental plates move together and create fold mountains (forced up).
When do constructive plate boundaries occur?
Constructive plate boundaries occur when plates move apart.
What is a hot spot?
A hotspot is a region within the Earth’s mantle from which heat rises - facilitates melting of rock.
How are igneous rocks formed?
-Igneous rocks are formed as a molten mixture of minerals (magma - upper part of the mantle). In places called hot spots, the crust is very thin/heavily cracked e.g. constructive plate boundaries. At destructive plate boundaries - produced different minerals.
Rate of erosion of igneous rocks:
VERY SLOW
-Strong and hard-resistant rocks e.g Granite, Basalt.
How are metamorphic rocks formed?
Metamorphic rocks are formed when exposed to high levels of heat (e.g. when magma intrudes into a rock/lava runs over the top) - changes minerals into new ones.
Rate of erosion of metamorphic rocks:
SLOW
- Crystalline rocks, resistant to erosion. Crystals orientated in one direction (foliation) - produce weaknesses.
e. g. Slate, Marble
How are sedimentary rocks formed:
-Sedimentary rocks are worn away by weathering + erosion. Fragments torn away and transported to another places (these are called sediments). Eventually will be deposited on top + weight will compress sediments, making them stick together to make a rock —> recess called lithification.
Rate of erosion of sedimentary rocks:
MODERATE/FAST
- Most sedimentary rocks are clastic and erode fast. Geological structure is weak.
e. g. sandstone, limestone.
