Oceans, Tides & Coasts

Question 1

what is an accretionary wedge?

Answer 1

a mass of sedimentary material scraped off a region of oceanic crust during subduction and piled up at the edge of a continental crustal plate (see diagram)

Question 2

what is continental shelf?

Answer 2

a part of the continental crust where the sea is relatively shallow compared with the open ocean, usually around a large land mass

Question 3

where do you find calcium carbonate deposits?

Answer 3

only in shallow seas - not deep oceans

Question 4

what happens to waves as they get close to shallow shore?

Answer 4

the waves slow down, the wavelength gets shorter

Question 5

what causes tides?

Answer 5

a consequence of the gravitational attraction of the moon and Sun - water closest to the moon bulges (as there is a stronger gravitational attraction)

Question 6

why do you find larger pebbles at the top of beaches and smaller pebbles at the bottom?

Answer 6

due to the power of the incoming wave, the stronger waves can carry larger pieces up to the top of the wave whilst the smaller pebbles don’t reach that far and get washed back down