AboutHawaii - About Hawaii About “Loveliest Fleet of...

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Unformatted text preview: About Hawaii: About “Loveliest Fleet of Islands Anchored in Loveliest any Ocean” any Where do the islands come from? Why do they form? Why How do they form? (V1) (V1) Hawaiian Archipelago Hawaiian Chain of islands that strikes NW - SE Chain across the northern Pacific Ocean across 3000 km from nearest continent & 800 km 3000 from nearest island from Each island is the summit of a great Each volcano that rises form sea floor volcano And is part of a great undersea mountain And range. range. Hawaiian Ridge & Emperor Seamounts Hawaiian Ridge Hawaiian NW Hawaiian Islands - Kure to Nehoa Flat or LOW Islands - coral & agal reefs Flat LOW 1750 km long & 5000 m above the sea floor Older than 6 million years Older Volcanic or HIGH islands - volcanoes Volcanic HIGH 650 km long & up to 4000 m above sea level • (what does this mean for total height?) SE Hawaiian Islands - Kauai to Hawaii Younger than 6 million years Located between Lat.19 - 21 N & Lon. 155 - 180 W Hawaiian-Emperor chain Main Islands & Volcanoes Main Oldest to Youngest Kauai - Kauai Niihau - Niihau Oahu - Waianae & Koolau Molokai - W & E Molokai Lanai - Lanai Maui - W. Maui & Haleakala Hawaii -Kohala, Mauna Kea, Hualalai, Mauna Hawaii Loa & Kilauea Loa Loihi Ages of volcanoes in m.y. Now, the question is Now, Where do these volcanoes come from? We know that most of the volcanoes & We earthquakes are located at plate margins! earthquakes AND Hawaii is located in the middle of the Hawaii Pacific Ocean, far from any plate boundary! boundary! So, how come volcanoes, earthquakes??? HOT SPOTS!!! HOT HOT SPOTS! HOT WHAT ARE HOT SPOTS? WHAT Hot Spots - deep, long-lived, mostly stationary mantle magma sources Expressed at the surface by: linear chain of volcanoes that age with distance from hot spot Over 100 identified Used as fixed points against which plate motion is measured Global distribution of Hot Spots Global Where do Hot Spots come from? Where Are thought to result from mantle plumes Are mantle hot, buoyant rock rising from the deep mantle plumes melt when they approach the surface Origin of mantle plumes is not known may come from as deep as the core-mantle may boundary boundary or made of recycled subducted plates?? Plate Tectonics & Hot Spots Plate Hot Spot Traces Hot Long chains of volcanoes with an age Long progression along their length progression Occur on both oceanic and continental Occur lithosphere lithosphere Form as plates move over a fixed magma Form source in the mantle source Therefore, they record plate motion Therefore, they relative to the mantle relative Hawaiian-Emperor chain Location of the various islands over the hot spot (red circle) at different times A Quick Review of Island Formation Formation Islands form over a “hot spot” in the mantle then move away riding the Pacific Plate Results in a chain of islands with an age progression along its length {Responsible for different magma types in different life stages, or whether there is any magma available at all} - when magma supply is low, erosion dominates shaping the landscape Homework #1: Homework #1: How fast does the Pacific Plate move over the Hawaiian Hot Spot? L2 & L3 L2 ...
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