EQ1 Flashcards
what are the 4 types of shore within the littoral zone
backshore
foreshore
nearshore
offshore
what areas within the littoral zone are we most concerned with due to erosion
the backshore and foreshore
why are we concerned with the backshore and foreshore
-Where the greatest human activity occurs
-Where the physical processes of erosion, deposition, transport and mass movement largely operated
is it true that the littoral zone changes due to processes within the sea and on the beach
TRUE
its constantly changing, due to the dynamic interaction between the processes operating in the seas, oceans and on land
what are the long and short term impacts to the littoral zone
Short term factors = individual waves, daily tides and seasonal storms
Long term factors = changes to sea level or climate change
what are the 2 types of coasts
rocky/cliffed coastlines
coastal plains
what are the characteristics of cliffed coastlines
-the transition of land to sea is abrupt
-at low tide the foreshore exposes a rocky wave cut platform
-the cliffs are vertical
what are the characteristics of sandy coastlines
-at high tide the sandy beach are submerged but the vegetated dunes are not
-vegetation plays a significant role in dune stabilisation
what are the characteristics of estuarine coastline
-extensive mudflats exposed at low tide and submerged at high tide
-backshore mudflats can become vegetated and form salt marshes
-transitions gradually from land to sea
what rocks are found at a resistant rock coastline
-Igneous rocks (basalt, granite)
-Older compacted sedimentary rocks (old red sandstone)
-Metamorphic rocks (slate and schists)
-These rocks are all resistant to the erosive powers of sea, wind, rain
what rocks do coastal plains consist of
-Eastern and southern coasts consists of areas of weaker and younger sedimentary rocks - clays, chalks, sand and sandstone
-an area of low, flat relief – referred to as a coastal plain
define coastal recession
coastal erosion
define lithology
the physical characteristics of particular rocks
define strata
different layers of rock
define bedding planes
these are natural breaks in the strata, caused by gaps in time during periods of rock formation
-horizontal cracks
define joints
these are fractures, caused either by contraction as sediments dry out, or by earth movements during uplift
-vertical cracks
define fold
formed by pressure during tectonic activity, which makes rocks buckle and crumble
define faults
formed when the stress or pressure to which a rock is subjected, exceeds its internal strength
define dips
this refers to the angle at which rock strata lie
(horizontally, vertically, dipping towards the sea or dipping inland)
what are the 3 types of rocks
sedimentary
metamorphic
igneous
examples of igneous rocks
granite
basalt
explain the erosion rate of igneous rocks
VERY SLOW due to:
-being crystalline, interlocking crystals make the rock resistant
-very few joints, fewer weaknesses for erosional processes to exploit
explain the erosion rate of metamorphic rocks
SLOW due to:
-crystalline metamorphic rock are resistant to erosion
-however the crystals often feature foliation where crystals face in one direction producing weaknesses
-often folded and heavily fractured – weaknesses exploited by erosion
examples of metamorphic rocks
slate
schist
marble
explain the erosion rate of sedimentary rocks
MODERATE to FAST due to:
-erode faster than metamorphic and crystalline igneous rocks
-the age is important, younger rocks tend to be weaker
-rocks tend to have many bedding planes and fractures making them vunerable to erosion
examples of sedimentary rock
chalk
sandstone
limestone
what are unconsolidated sediments
the weakest coastal material because they consist of loose materials and are not cemented together.
example of unconsolidated sediments
boulder clay
what are the 3 types of permeabilities within geology
impermeable
permeable
porous
Which rock types are impermeable
IGNEOUS
METAMORPHIC
which rock type is permeable
SEDIMENTARY specifically limestone and sandstone
which rock type is porous
SEDIMENTARY specifically chalk
what 2 factors influence cliff profiles
-The resistance to erosion of the rock
-The dip of rock strata in relation to the coastline
what is the importance of vegetation on coastlines
Many coastlines are protected from erosion of unconsolidated sediment by the stabilising influence of vegetation
examples of vegetation that protect coastlines
mangrove swamps
salt marshes
how does vegetation stabilise sediment (important please know this yasmine)
-The roots of plants bind sediment particles together making them harder to erode (sand dunes + salt marshes)
-When submerged, plants growing in sediment provide a protective layer so the surface of the sediment isn’t directly exposed to moving water and therefore erosion reduces (salt marsh only)
-Plants protect sediment from wind erosion by reducing wind speed at the surface due to friction with the vegetation (sand dunes only)
what conditions can halophytes tolerate
Halophytes can tolerate salt water, either around their roots, being submerged in salt water (at high tide) or salt spray from the sea
what conditions can xerophytes tolerate
Xerophytes can tolerate very dry conditions, such as those found on coastal sand dunes where the sandy soil retains very little water due to drainage
why have coastal vegetation become a key part of coastal management
sand dunes, mangroves and salt marshes reduce the risk of flooding and erosion
what is plant succession
Succession refers to the changing structure of a plant community overtime
as an area of initially bare sediment is colonised by plants
what is the importance of plant succession
The process is especially important on coasts because of its role in coastal accretion
what is coastal accretion
a continuous net deposition of sediment
what are pioneer species
deposition takes place certain
very specialised plants will begin to grow in the bare sand or mud.
They begin the first stage of plant succession
what does each step in plant succession called
seral stage
what is a psammosere
a sand dune ecosystem
what is a halosere
a salt marsh ecosystem
what is a concordant coastline
This is where bands of more resistant and less-resistant rock run parallel to the coast
what is a discordant coastline
occurs where bands of differing rock type run perpendicular to the coast.
what is a dalmation coastline
composed of long, narrow islands running parallel to the coastline and separated from the coast by narrow sea channels called sounds. They are produced by sea level rise flooding the coastline
what is a haff coast
it consists of concordant features - long spits of sand and lagoons – aligned parallel to the coast
