Coasts key terms and ideas Flashcards
(43 cards)
What is the littoral zone?
The wider coast which is split into subzones-
Offshore
Nearshore
Foreshore
Backshore
Coast
What are the key features of a marine erosion dominated cliff face?
-Limited debris
-Steep face
-Active undercutting
What are the key features of a sub-areal erosion dominated cliff face?
-Accumulated debris
-Lower angle face
-Accumulated debris
What 3 parts make up ‘sub-areal’ erosion?
Weathering-Chemical, biological, mechanical breakdown of rocks
Mass movement-Landslides, slumps, rockfalls. Move material down a slope
Surface runoff-Water, usually during heavy rain flowing down cliff face and eroding it
Explain primary and secondary coasts
Primary= Dominated by land-based processes eg deposition at coast from rivers or new coastal land formed by lava flows
Secondary= Dominated by marine deposition/erosion processes
Explain submergent and emergent coastlines
Sub= Being flooded by sea, due to rising sea levels and or falling land eg rias and fjords
Emer=Where coasts are rising relative to sea level eg during tectonic uplift
What is a concordant coastline?
When rock strata runs parallel to the coastline. AKA pacific coasts
What is a discordant coastline?
When rock strata runs perpendicularly to coastline. AKA Atlantic coasts
What is a coastal plain?
A low lying relief area close to the coast, often contain wetlands because they’re only just above se level
What is coastal accretion?
The deposition of sediment at the coast, causing seaward growth of coastline, often involves deposited material being stabilised by vegetation
What is dynamic equilibrium?
When deposition and erosion are happening at the same rate
What is strata?
The different layers of rock within an area and how they relate to each other
What is faulting?
The presence of major fractures that have moved rocks from their og positions
What is deformation?
The degree of which rocks have been deformed(tilted or folded) by tectonic activity
What was the Holocene?
Geographical epoch, began about 12,000 years ago.
Its early stages were marked by large sea level rises of about 35m+a warming interglacial climate
Define igneous rocks
Crystalline, the interlocking crystals make it a strong, hard, erosion-resistant rock.
Often have very few joints-minimises weaknesses that can be exploited by erosion.
Erode very slowly about 1mm/yr
Eg, granite, basalt
Define metamorphic rocks
Crystalline metamorphic are very resistant to erosion about 1mm-10cm/yr
Many metamorphic rocks have a feature called foliation
Often folded and heavily fractured=weaknesses
Eg, slate, marble
What does foliation mean?
Where crystals in a rock are all orientated in one direction=weaknesses
Define sedimentary rocks
Most are clastic and erode faster than crystalline igneous.
Age of rock is important, geologically young rocks tend to be weaker
Erode relatively fast, 10cm -several meters/yr.
Eg, Sandstone, limestone
What is pore water pressure?
Th pressure water experiences at a particular point due to the water weight above it
Happens lots in cliff faces with permeable rocks=unstable
How does vegetation help protect the coastline?
-Protect sediment from wind erosion by reducing wind speed, from friction with leaves
-Roots bind sediment together
-Provide nutrients, humus
How do the plants survive at the coast?
Xerophytes=tolerate dry conditions, eg in sand dunes where sandy soil retains little water
Halophytes=tolerate salty water, eg spray from sea or being submerged at high tides
What is plant succession?
Structure of plant community in area over time, eg…
Embryo->fore->yellow->grey.
What is a sand dune ecosystem called?
Psammosere
