8.4 MARINE PROCESSES AND WAVES

Question 1

what are waves caused by?

Answer 1

-friction between wind and water with some energy
-force of wind blowing on surface of water generates ripples which grow into waves

Question 2

what does wave size depend on?

Answer 2

-strength of wind
-duration wind blows for
-water depth
-wave fetch

Question 3

what is the fetch?

Answer 3

-the uninterrupted distance across the water over which wind blows
-so waves grow in size

Question 4

what are tides caused by?

Answer 4

-gravitational pull of the moon acting on water on the earths surface

Question 5

how can wave frequency be measured?

Answer 5

-time the gap in seconds between the arrival of one wave crest and the next

Question 6

what do constructive waves have?

Answer 6

-strong swash
-weak backwash

Question 7

what do destructive waves have?

Answer 7

-weak swash
-strong backwash

Question 8

beach profiles may change due to?

Answer 8

-sediment supply from rivers being reduced due to the construction of dams that trap sediment upstream
-interface in sediment supply along coast

Question 9

what is the swash?

Answer 9

-the flow of water up beach as wave breaks

Question 10

what is the backwash?

Answer 10

-when water runs back down the beach to meet incoming wave

Question 11

what is beach morphology?

Answer 11

-shape of beach including width and slope

Question 12

what do storm beaches result from?

Answer 12

-high energy deposition of course sediment during storms

Question 13

what do berms result from?

Answer 13

-summer swell wave deposition

Question 14

what are offshore ridges formed by?

Answer 14

-destructive wave erosion

Question 15

what is hydraulic action?

Answer 15

-air trapped in cracks is compressed by force of waves crashing
-the pressure forces cracks open, more air trapped
-dislodges blocks of rock from cliff face

Question 16

what is abrasion?

Answer 16

-sediment picked up by breaking waves is thrown against cliff face
-this chisels away at surface, removing small rock particles

Question 17

what is attrition?

Answer 17

-as waves move sediment around the collisions chip fragments of the sediment
-sediment gets smaller and rounded overtime

Question 18

what is corrosion?

Answer 18

-carbonate rocks are vulnerable to solution by rainwater and seawater

Question 19

how is wave cut notch formed?

Answer 19

-eroded at base of cliff by hydraulic action and abrasion
-as notch becomes deeper the overhanging rock collapses
-cliff recedes inland

Question 20

what is a blow hole?

Answer 20

-forms when coastal cave turns upward and breaks through flat cliff top