Plate Tectonic Control on Coastal Systems

Question 1

Tectonic Coastal Classification

Answer 1

The basis for classification is based upon the position of the coast with respect to a plate boundary.

1. Position of the plate (middle or edge)
2. Age of the coast
3. Exposure of the coast to open ocean processes (waves)

Question 2

What are the three major classifications of coasts?

Answer 2

1. Collision Coast
2. Trailing-Edge Coast
3. Marginal Sea Coast

Question 3

What are the attributes associated with a collision coast?

Answer 3

• Site of subduction zone
• Mountains
• Trenches parallel the coast
• Tectonically active
• Narrow continental shelf
• Few depositional features

Question 4

What is one example where a depositional feature is present on a collision coast?

Answer 4

Gulf of Alaska, Chugach Mountains:

• Glaciers erode the coast causing a large amount of sediment input
• Sediment input is outpacing sea level rise
• Since this site is mixed between wave and fluvial energy, barrier islands are starting to form along the coast.

Question 5

How do trenches play a role in sediment supply on collision coast? Draw diagram.

Answer 5

Use ocean-continent collision diagram.

Question 6

What characteristics are associated with trailing edge coast?

Answer 6

• Opposite side of a collision coast
• not found on a plate boundary
• generally face a mid-ocean ridge
• coincides with middle of the plate

Question 7

What are the three types of trailing edge coast?

Answer 7

1. Amero-Trailing Edge Coast
2. Afro-Trailing Edge Coast
3. Neo -Trialing Edge Coast

Question 8

Amero Trailing Edge Coast

Answer 8

• Face spreading zones (mid-ocean ridges)
• coincide with the middle of the plate
• The opposite side of the continent from collision coast

Example: East Coast of North and South America

Question 9

Amero-Trialing Edge Coast Characteristics

Answer 9

• Wide Continental Shelf
• Backed by wide coastal plain
• lack of tectonism
• An abundant amount of sediment

Question 10

Afro-Trailing Edge Coast

Answer 10

• Both sides of the coast face a spreading zone.
• Sediment discharge and the presence of depositional features vary.
• The entire continent is within a plate.
• No tectonism
• Wide narrow continental shelf

Example: Africa and Greenland

Question 11

Neo-Trailing Edge Coast

Answer 11

• coast face a new spreading zone
• geologically young

Question 12

Neo Trailing-Edge Coast Attributes

Answer 12

• Crust still undergoing adjustments to rifting
• very few rivers
• Narrow to non-existent continental shelf
• Few depositional features.

Question 13

Marginal Sea Coasts

Answer 13

• Protected from ocean currents & swells
  
  • Protected side of an island arc system
• Occurs along the continental coast facing an island arc system.

Question 14

Attributes of Marginal Sea Coast

Answer 14

• High sediment influx
• No tectonism
• Some depositional features (usually associated with river deltas)