1. Lesson 2.3: Islands
*Refer to Chapter 13 in your Textbook

2. Lesson 2.3 Learning Goals:
Explain how a hotspot forms an island chain.
Label the structure of a barrier island.
Differentiate between the 3 types of reefs.

3. Hot Spots
Wilson (1963)
Volcanoes can form in the middle of a plate where magma rises upward until it erupts on the sea floor, at what is called a “hot spot”
The hotspot will stay still as the plate moves, creating a chain of islands

4. Hot Spots

5. Barrier Islands
Barrier Islands form when a piece of the mainland is broken off and separated by a body of water (lagoon)
They can be very large and can be ideal for beaches & hotels, but are also vulnerable to erosion and weather

6. Barrier Islands

7. Barrier Island Structure
Ocean, Beach, Dune, Flat, Marsh, Lagoon
Dune: top of the beach, usually inclining to protect the coastline
Barrier flat: thick vegetation
Salt marsh: swamp

8. Reef Formation Fringing: Most common Form along shoreline of coast or
island
The fore side (facing the ocean) has
the most biological activity

9. Reef Formation Barrier: Forms when island begins to sink or
when there is a rock for the coral to
grow on
Separated from land by a lagoon
Usually much larger than a fringing
reef

10. Reef Formation Atoll: Forms when island sinks below sea level
The remains of the island are carried
away by the tectonic plate, leaving
behind a circular reef