1. Lesson 16: Coastal Dynamics Geological Oceanography

2. The Earth’s coasts
There are two main ways to classify coasts: 1) based on location and 2) based on coastal formation
Coasts are constantly changing as a result of natural processes
Human activities also modify the coasts

3. Coasts can be classified based on geological location
Active coasts are close to plate boundaries where plate collisions result in volcanoes and earthquakes
Passive coasts are far away from plate boundaries and have little volcanic activity and earthquakes

4. Identify the active and passive coasts
Plate boundaries
are shown in bright yellow
Is the Pacific coast
active or passive?
What about the Atlantic
coast?
Active! It is right
near a plate boundary
Passive! It is far
from a plate boundary
Photo: NOAA

5. Coasts can also be classified based on the way that they are formed
Primary coasts
Secondary coasts
Definition
Formed by processes not related to ocean activity (more land-driven)
Formed by marine activity
Formation processes
Land erosion
Plate tectonic activity
Sedimentation
Wave erosion
Building by marine life

6. Two types of primary coasts
Photo: USGS
Deltas
Wide continental shelf
Accumulated sediment forms
a triangular shape
Volcanic coasts
Volcanoes build up on
the sea floor, eventually
breaking the surface and forming
island chains
Nile River Delta
Teacher’s Note: There are multiple types of primary and secondary coasts. Two examples of each were chosen to fit best within the lesson’s time frame, and your students should be aware that there are others.
Photos:
Nile River Delta
Accessed: November 2010
Hawaiian Islands
Accessed: November 2010
Photo: NOAA
Hawaiian Islands

7. Two types of secondary coasts
Photo: NASA
Marine-deposition coast
Sea action causes sediment
accumulation in one place forming
mud flats, salt marshes,
beaches and barrier islands
Coasts built by organisms
Organisms build structures
like coral reefs and mangroves
Barrier Island, Mexico
Photos:
Barrier Island
Image courtesy of the Image Science & Analysis Laboratory, NASA Johnson Space Center
ISS016-E-22098
Great Barrier Reef
Accessed: November 2010
Photo: NASA
Great Barrier Reef, AUS

8. Coasts are dynamic, constantly changing
What types of processes do you think might affect coasts?
Natural processes like wind, waves, currents and erosion move sediments and change primary and secondary coasts
Erosion refers to the breakdown and transport of sediment, sand, rock and other material by physical forces
Wind and waves can move sand and other sediment and can wear away rocks near the shore

9. How do human activities shape the coasts?
Human activities can impact coastal processes, as well
In today’s activity, we will explore the effects of a manmade navigation channel on a delta in Louisiana