3.3 - Depositional Landforms

Question 1

How are beaches formed?

Answer 1

Sediment is imout, transported, and deposited by constructive waves’ swash
Waves don’t have enough energy to carry sediment further

Question 2

How do spits form?

Answer 2

LSD (waves coming in at an angle and being backwash at 90° by gravity) and sediment is extended offshore by constructive waves
Wind direction dictates the curve of the spit

Question 3

What makes a spit recurved?

Answer 3

Two dominant wind directions causes two LSD directions

Wave refraction around tip of spit

Question 4

How does an offshore bar form?

Answer 4

1) Waves break on a submerged bar
Sediment carries is despoiled and it accumulates vertically

2) Sediment carries by LSD along the coast
Waves enter low-energy part of sediment cell
Sediment gets deposited on submerged bars parallel to the shore

Question 5

How do tombolos form?

Answer 5

Offshore island refracts approaching waves so convergence of two LSD directions on opposite side of the island
This creates a bar which extends out to mainland