Island Formation
The Hawaiian Islands have never been attached to a continent. They are high islands (islands of volcanic origin).
Oahu, like the rest of the Hawaiian islands, serves as the tip of suboceanic mountains sitting on the pacific plate. The fissure that created Oahu has been actively producing this molten rock for more than 25 million years. Two major volcanic formations have developed on Oahu. These are the Waianae and Koolau ranges, which are both shield volcanoes. The latest volcanic activity on Oahu was the eruption of the Diamond Head and Koko Head volcanoes, which occured approximately 10,000 years ago. Oahu is one of the oldest of the main Hawaiian islands. Because of Oahu’s age, it and its Kauai island have the most diverse ecological system of the Hawai’ian islands. Oahu also experienced the largest known example of a landslide. The Nuuanu landslide deposit has a volume of approximately 5000 m, is 200 km wide and had very large intact blocks of land.
Oahu, like the rest of the Hawaiian islands, serves as the tip of suboceanic mountains sitting on the pacific plate. The fissure that created Oahu has been actively producing this molten rock for more than 25 million years. Two major volcanic formations have developed on Oahu. These are the Waianae and Koolau ranges, which are both shield volcanoes. The latest volcanic activity on Oahu was the eruption of the Diamond Head and Koko Head volcanoes, which occured approximately 10,000 years ago. Oahu is one of the oldest of the main Hawaiian islands. Because of Oahu’s age, it and its Kauai island have the most diverse ecological system of the Hawai’ian islands. Oahu also experienced the largest known example of a landslide. The Nuuanu landslide deposit has a volume of approximately 5000 m, is 200 km wide and had very large intact blocks of land.
Sources:
-Glenda Bendure & Ned Friary, Oahu, Lonely Planet Pub: 2003, 13-20.
-O.G. Sorokhtin, G.V. Chilingarian, N.O. Sorokhtin, Evolution of Earth and its Climate: Birth, Life and Death of Earth. 230.
-"Hawaii” Encyclopaedia Britannica. Encyclopaedia Britannica Online Academic Edition. Encyclopædia Britannica Inc., 2015. Web. 01 May. 2015. http://www.britannica.com/EBchecked/topic/257332/Hawaii. encyclopedia of islands, 536-537.
-History and Formation Image 1 http://www.classroomatsea.net/general_science/images/plume_sequence.jpg
-History and Formation Image 2 http://www.hawaii.edu/environment/ainakumuwai/assets/src_images/Matt's_Island_Diagram.jpg
-Glenda Bendure & Ned Friary, Oahu, Lonely Planet Pub: 2003, 13-20.
-O.G. Sorokhtin, G.V. Chilingarian, N.O. Sorokhtin, Evolution of Earth and its Climate: Birth, Life and Death of Earth. 230.
-"Hawaii” Encyclopaedia Britannica. Encyclopaedia Britannica Online Academic Edition. Encyclopædia Britannica Inc., 2015. Web. 01 May. 2015. http://www.britannica.com/EBchecked/topic/257332/Hawaii. encyclopedia of islands, 536-537.
-History and Formation Image 1 http://www.classroomatsea.net/general_science/images/plume_sequence.jpg
-History and Formation Image 2 http://www.hawaii.edu/environment/ainakumuwai/assets/src_images/Matt's_Island_Diagram.jpg