Geology of the Hawaiian Islands

Geology of the Hawaiian Islands

Objectives:1. Describe island formation.2. List stages of Hawaiian volcano formation.3. List volcanoes which make up the Big Island.4. Identify active volcanoes in the Hawaiian Islands.5. Tell the ages of the Hawaiian Islands.6. Describe pioneer and climax communities.7. Define endemic, indigenous, exotic species, and give

examples found in the Hawaiian Islands.

Hawaiian Island Formation• Islands formed as the

Pacific Plate moved northwest over a "hot spot”– hot spot = hot plume of

mantle material rising through the crust

– Video• Niihau and Kauai were the

first major islands to form, followed by Oahu, Molokai, Lanai, Maui, Kahoolawe, and the Big Island.

Island Formation

• Emperor Seamounts and Northwestern Hawaiian Islands are older – lie to the northwest

• The Big Island is made up of five volcanoes:– Kohala (extinct)– Mauna Kea (dormant)– Mauna Loa (active)– Hualalai (active)– Kilauea (active and currently

erupting)**USGS does not acknowledge

“dormant”

Northwest Hawaiian Islands

Island Formation

• Lo'ihi – New island forming– 13,000 ft high above the sea

floor but is still 3,000 ft below the ocean’s surface.

• Oldest northwest Hawaiian islands began forming 70 million years ago– Kauai approx. 5 mya – Big Island at 0.8 mya.

Video

• http://www.history.com/shows/how-the-earth-was-made/videos/how-was-hawaii-formed#how-was-hawaii-formed

Stages of Island Formation

1. (Active Volcano) Then, Pacific plate moves northwest and the island is cut off from the magma source and becomes extinct.

1. (Eroded Island) Over time, erosion and weathering gradually break down the island into the ocean, but coral reefs grow.

1. (Atoll) Eventually all that is left above ocean level is an atoll, which are circular-shaped coral reef remnants that once surrounded the island.

1. (Seamount) Once the islands and surrounding reefs drop completely below sea level they are called “seamounts”.

Arrival of life to Hawaii

Pioneer communities – organisms that first settle on the barren lava– mostly producers– plant seeds dropped by birds

“wings”, ocean currents “waves”, “winds”

Types of Species

a) indigenous – naturally occurring species• arrived on the islands through the air or water

naturally• But also occur in other places

Types of Speciesb) endemic – naturally occurring species found only in Hawaii

• Examples:– Hawaiian Lionfish– Hawaiian Sergeant– Waxy Cowry– Banded Spiny Lobster– Laurent's Hermit Crab– Hawaiian Monk Seal

**Both indigenous and endemic are native

Types of Species

c) exotic/introduced – species brought by humans

• usually threaten indigenous species due to lack of natural predators• examples:– feral pigs– rats–Mongoose

• “Invasive Species” – exotic species that take over environments

Invasive Species

• Gorilla ogo

• “ogo” = seaweed

Fountain Grass

Mongoose

Coqui Frog