Coasts Shaped by Deltas

Geography · 10 questions

Ten questions on delta forms, sediment deposition, and coastal processes.

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1. Which feature most clearly characterizes a bird’s-foot delta?

   1. Finger-shaped distributary channels toward the sea
   2. A broad, arcuate delta front
   3. A long beach parallel to the coast
   4. An estuary divided by tidal channels
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   A) Finger-shaped distributary channels toward the sea

2. Which coastal process is most associated with an arcuate delta shoreline?

   1. Wave-driven sediment redistribution along the coast
   2. Tide-driven widening of channels
   3. Wind-driven formation of coastal dunes
   4. Glacier-driven accumulation of coastal moraines
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   A) Wave-driven sediment redistribution along the coast

3. In delta formation, what does “progradation” mean?

   1. Inland movement of the salinity boundary
   2. Lateral migration of distributary channels
   3. Vertical subsidence of the delta surface
   4. Seaward shoreline advance through sediment deposition
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   D) Seaward shoreline advance through sediment deposition

4. What is the name for a sediment lobe deposited on a delta plain when floodwater breaches a levee?

   1. Foreset bed
   2. Tidal delta
   3. Crevasse splay
   4. Mouth bar
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   C) Crevasse splay

5. What feature of a delta is described by the terms topset, foreset, and bottomset?

   1. The intensity of wave erosion along the coast
   2. The position and slope of sediment layers
   3. The water depth of tidal basins
   4. The flow direction and speed of distributary channels
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   B) The position and slope of sediment layers

6. What happens when channel avulsion occurs on a delta plain?

   1. Sediment deposition at the river mouth stops entirely
   2. Waves distribute coastal sediment evenly
   3. Tidal flow deepens the old channel
   4. River flow shifts into a new channel
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   D) River flow shifts into a new channel

7. In what setting can back-barrier marshes develop near deltas?

   1. High-pressure areas on the deep-sea floor
   2. Strongly wave-exposed open coasts
   3. Low-energy areas sheltered by coastal barriers
   4. Fast-flowing areas on mountain slopes
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   C) Low-energy areas sheltered by coastal barriers

8. What is the most direct effect of a large upstream dam on a delta coast?

   1. An increase in the coastal tidal range
   2. A change in the dominant coastal wave direction
   3. A fall in regional sea level
   4. Reduced sediment supply reaching the delta
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   D) Reduced sediment supply reaching the delta

9. If river discharge decreases, how can saltwater intrusion in delta channels change?

   1. Saltwater can extend farther inland
   2. Coastal tides can disappear
   3. Saltwater can retreat farther from the coast
   4. Sediment deposition on the channel bed can stop entirely
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   A) Saltwater can extend farther inland

10. What is the name for a submerged sediment body where a distributary channel enters the sea?

    1. A natural levee along a distributary channel
    2. Mouth bar
    3. A coastal spit along the shoreline
    4. A foreset bed on the delta slope
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    B) Mouth bar