coastal landforms on sea level change

Question 1

what can sea level changes result from

Answer 1

-a change in sea level of acutal sea
-downward or upward movement of the land

Question 2

what determines where there is an overall rise or fall in sea level

Answer 2

-the fastest or most significant movement (change in sea level or movement of land)

Question 3

whats a positive change

Answer 3

an overall rise in sea level

Question 4

whats a negative change

Answer 4

an overall fall in sea level

Question 5

what is marine transgression

Answer 5

-when there is a rise in relative sea level and sea flows over the land
-cover areas which would have been exposed before

Question 6

what is marine regression

Answer 6

-sea levels fall
-land once inundated by the sea is revealed

Question 7

what will coasts do during marine regression and transgression

Answer 7

regression- advance
transgrresion- retreat

Question 8

what are changes in level of the actual sea called

Answer 8

eustatic changes

Question 9

what are movements associated with the depression or uprising of land called

Answer 9

isostatic movements

Question 10

what are isostatic movements of land due to

Answer 10

-the addition or reduction of weight
-due to accumulation of sediments, ice or large quantities of lava flows
is a localised impact

Question 11

what scale effect do eustatic changes have

Answer 11

a global effect due to interconnected nature of worlds oceans basins

Question 12

what is glacio-eustatic

Answer 12

-changes in sea level due to accumulation and melting of ice that covers continental land

Question 13

what doesnt influence the sea level

Answer 13

-growth or decline in size and amount of floating sea ice
-because sea will displace equivalent of its own mass of water

Question 14

what effect does acculumation of ice during glacial advance have

Answer 14

-can depress the earths crust

Question 15

what does melting of ice during interglacials result in

Answer 15

-isostatic rebound
-land uplifts to restore state of equillibrium

Question 16

what is hydro-isostatic subsidence

Answer 16

-as ice melts there is a eustatic sea level rise
-results in marine transgression and weight of water can depress the continental shelf

Question 17

what are steric changes

Answer 17

-how changes in atoms in molecule are arranged

Question 18

what are examples of steric changes

Answer 18

-as oceans cool they reduce in size
-as oceans warm, they expand in size
-known as thermal contraction and expansion
-decrease in salinity will result in sea level rise

Question 19

whats an epeirogenic movement

Answer 19

-large scale vertical tectonic motions of crust involving depression or uplift of ocean floors and continents

Question 20

what are tectono eustatic changes

Answer 20

-linked to epeirogenic movements
-if shape of ocean basin is altered, reduced in size and global rise in sea level

Question 21

what are orogenic movements

Answer 21

-associated with mountain building epsiodes in places where tectonic plates converge

Question 22

how do orogenic movements influence the land

Answer 22

-in mountain building regions, displacement in height of land can be gradual or sometimes sudden (eq)
-when displacement leads to uplift of land- lower sea level
-when displacement leads to loweing of land- higher relative sea level

Question 23

what are sedimento eustatic global changes?

Answer 23

-due to sediment accumulation
-large accumulation of sediments carried from land to offshore locations

Question 24

effect of sedimento eustatic changes on sea level

Answer 24

-can reduce basins holding capacity
-rising sea level
-sediment mass could depress ocean floor, increasing oceans volume leading to fall in sea level

Question 25

steps of sea level change due to glacial advance and retreat

Answer 25

-during glacial period, temp fall and ice sheets, caps and glaciers form on land leading to global eustatic fall (negative change) -continental ice increases in size (localised isostatic depression of land) creating positive change -temp rise during interglacial, ice melts, global eustatic rise in sea level (positive change) -continental ice melts as weight of land decreases isostatic uplift takes place (localisd negative change in base level)

Question 26

when are emergent coastlines created

Answer 26

when there is a relative fall in sea level

Question 27

when are submergent coastlines created

Answer 27

-when there has been a rise in relative sea level

Question 28

landforms on emergent coastlines

Answer 28

-raised beach with former beach material or wave cut platform now vegitated -present storm beach -fossil sea cave -old wave cut notch -cliff seperating raised beach and present beach

Question 29

when are emergent coastlines evident

Answer 29

-when each deposits and marine shell beds found above present day high tide level

Question 30

when does a terrace form

Answer 30

-the raised shore platform with beach deposits creates terrace -indicated sea must have been at a relatively fixed level for a long time to have allowed platform to develop

Question 31

what causes the relict cliffs to not be as steep

Answer 31

-break down via sub-aerial processes

Question 32

what happens to depositional features in emerging coastlines

Answer 32

-salt marshes increase their extent -beaches and dunes may widen as sediments washes ashore

Question 33

landforms on submergent coastlines

Answer 33

-rias and fjords

Question 34

what does positive change in sea level mean

Answer 34

-overall shape of coastline will be changed

Question 35

what happens when sea levels rise (either eustatic rise or tectonic subsidence)

Answer 35

-some features origionally formed at sea level wjem seas where lower than present completely submerged

Question 36

where are rias more common

Answer 36

-along discordant coastlines

Question 37

how do rias form

Answer 37

-when global sea levels lower than present, base level lowered, rivers have potential energy to cut downwards -rivers erode deep river valleys -when sea levels rise, deepended segments of river filled as sea level increase

Question 38

what are the characteristics of rias

Answer 38

-dendritic draining pattern

Question 39

what are fjords

Answer 39

-drowned glacial valleys shaped by action of ice and been submerged

Question 40

where are fjords best formed

Answer 40

-at higher altitudes where effects of ice are more profound

Question 41

features of fjords

Answer 41

-steep sides -flat bottoms -U shaped valley -straight sided and more narrow than rias -submerged lip at seaward end-marks former extent of glacier

Question 42

what happens to depositional landforms due to emergence

Answer 42

-salt marshes widened may shrink

Question 43

what are fiards

Answer 43

-sumbmurged lowland areas that have been glaciated in past -much wider and shallow and less branhed than fjords

Question 44

what is glacioeustacy

Answer 44

-oscillation in sea level due to advance or retreat in ice

Question 45

what is glacioisostacy

Answer 45

oscillation in land level due to advance or retreat in ice

Question 46

what is the process of sea level change called

Answer 46

eustacy

Question 47

what is the process of land level change called

Answer 47

isostacy

Question 48

what is the name for when land returns to normal/ equillibrium

Answer 48

isostatic rebound

Question 49

what do the features of a submergent coastline depend on

Answer 49

-if the drowned coastline was previously an upland or lowland area

Question 50

what does the effect of an upland area have on submergent coastlines

Answer 50

-when drowned, water off coast tends to be quite deep -wave action is strong so more erosion landforms like cliffs and headlands

Question 51

what is the effect of submerging a lowland area

Answer 51

-when drowned, water tends to be quite shallow -at low tide, extensive areas of sand and mud exposed -encourages deposition like salt marshes and dunes

Question 52

on an emergent coastline, what is a raised beach?

Answer 52

-a clear ledge in the bay

Question 53

on an emergent coastline, what is a relic cliff?

Answer 53

-sharp rise in the level of land that marks the position of the cliffs that were once on the coast