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

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.

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

Hot Spots

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

Barrier Islands

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

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

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

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