Chapter 2- Temporial variations and their influence on coastal environments

Question 1

What are tides? How do tides influence the formation of coastal features? (4 marks)

Answer 1

Tides are movements up and down of the water adjacent to the coast (1).
*They are caused by the gravitational pull of the moon (1).
*The active area of coastal erosion lies more or less within the area between the points of lowest and highest tides (1).
*Only if the high tides regularly reach the cliff line the cliffs will gradually be eroded back (1).
*Between high and low tide the main processes of transport, abrasion, attrition, sorting, etc. by marine processes will take place (1).

Question 2

what does moon do in tide

Answer 2

pulls water towards it and there is a compensatory bulge on the opp side of the earth
the area of the world between budlges, the earths at its lowest

Question 3

whats tidal range

Answer 3

The difference between the high and low tide

Question 4

what type of coasts are tide dominated

Answer 4

lowland sandy estuarine coasts

Question 5

what coastline example experience semi diurnal tides

Answer 5

open atlantic coastlines

Question 6

what coastline recieve diurnal tide

Answer 6

antartica

Question 7

whats semi diurnal tide

Answer 7

2 high and 2 low tides approx every 24 hrs

Question 8

whats diurnal tide

Answer 8

1 high tide and 1 low tide a day as

Question 9

what do tides ciruclate around

Answer 9

amphidromic points due to the earth rotation (coriolis effect)

Question 10

whats tidal range

Answer 10

difference in height of sea water at low and high tide

Question 11

what do tidal ranges determine

Answer 11

upper and lower limits of erosion and deposition and the amount of time a day the litorral zone is exposed and open to sub ariel weathering

Question 12

whens tidal range highest and lowest

Answer 12

highest at spring lowest at neap

Question 13

micro tidal coast tidal range

Answer 13

less then 2m

Question 14

macro tidal coast tidal range

Answer 14

more then 4

Question 15

micro tidal coast example

Answer 15

Australia

Question 16

micro tidal coast what occurs

Answer 16

wave breaking is concentrated in a narrow vertical zone throughout the tidal cycle so well defined erosional features such as wave cut notches are formed at the foot of cliffs

Question 17

macro tidal coast example

Answer 17

most of UK coast and BAy of fundy in America

Question 18

macro tidal coast what occurs

Answer 18

wave eenrgy is distributed over a wide area, so tis erosional capcity is less resulting in more depositional features

Question 19

what occurs during the durnal rise and fall of tides

Answer 19

wetting and drying of the substrata occurs

Question 20

substrata in macro tidal

Answer 20

more substrata is exposed or submerged and effected by processes such as salt weathering

more liekley to have sand dunes wide expanse of deposition sand which dries and can be transported landward by aelonian processes

Question 21

whats a current

Answer 21

permanent or seasonal movement of surface water in seas and ocean

Question 22

as water rises w the tides it produces what and what occurs

Answer 22

tidal currents
floods ITZ causing entrainment and deposition of material

Question 23

whats fallign tide in tidal current

Answer 23

ebb tide which carries material in opp direction

Question 24

velocity in tidal current

Answer 24

max at midpoints whereas at high and low water current velocity slacks leading to deposition

Question 25

tidal current velocity in rivers and what occurs

Answer 25

critical current velocity thresholds for tidal currents to transport diff particle sizes muds in low energy low and high intertidal areas, while sand shoals occur in mid intertidal areas

Question 26

whats a shore normal current

Answer 26

when waves approach shore w crests parralel to coastline warer carried up beach but there has to be a return flow

Question 27

whats a rip current

Answer 27

strong currents moving away from shoreline develop when seawater piles up along the coastline by incoming waves

Question 28

whats an energetic flow

Answer 28

periodic and associated w high levels of river flood discharge

Question 29

constructive and destructive wave height

Answer 29

c- under 1m d- over 1m

Question 30

length of con and destructive

Answer 30

con- long up to 100m des- short typically 20m

Question 31

frequency of con and des

Answer 31

con- 8-10 per min des- 10-14 a min

Question 32

water movement of des and con

Answer 32

con - surging des- spilling or plungin

Question 33

what happens to waves as they approach shallow water

Answer 33

circular motion of water in the wave shape is effected by the sea floor. as water depth decreases, the water path movements change from circular to elliptical shape , wave length and velocity decrease and wave heigh incr, the wave steepens and rbeakes on the shore , to produce diff types of breaking wave depending on ocean floor gradient