The Hawaiian Island Chain

Geology of the Hawaiian Island Chain

The chain of Hawaiian Islands formed as the Pacific plate moved over a hot spot in the mantle of the Earth. The plate slowly moves northwestward at a rate of about 32 miles per million years. The northwestern islands are older and generally smaller due to prolonged exposure and erosion. Plate tectonics, types of volcanoes, hot spots, and sea mounts, are all an important part of the geology of the hawaiian island chain. Plate tectonics is a theory that Earth’s crust is composed of nearly a dozen plates, which have shifted around the surface of the Earth over time. This theory provides a reasonable explanation for how mountains formed, and why there are earthquakes and volcanoes. Additionally, this

The hot material deep within the surface of the Earth melts to produce magma beneath the Pacific Plate. Each of the volcanoes in the Hawaiian island chain go through a series of stages in their lifetime. In short, the shield stage, postshield stage, erosional stage, rejuvenated stage, coral atoll stage, and the guyot stage. The shield stage is divided into three phases, the submarine, explosive, and subaerial. Following the gentle explosions of the pre shield stage, the submarine phase begins with pillow lava eruptions. The volcano slowly makes its way up to sea level and the submarine phase ends when it is shallowly submerged. The explosive phase begins when the volcano breaches the surface. Upon contact to air, a large amount of steam is produced and the lava becomes volcanic ash. Following the explosive phase is the subaerial stage which primarily consists of the “shield” shape forming and landslides. Following the shield stage is the post shield stage. In this stage, the type of lava changes and eruptions become more explosive. The new lava flows increase the slope and eruption rate gradually decrease over a period of 250,000 years. As the volcano becomes dormant, the erosional stage takes place. The mountain loses elevation and subsides into the oceanic crust. Erosion also causes deep valleys and coral reefs to form. The rejuvenated stage occurs after a long period of dormancy. During this stage, the volcano erupts small amounts of lava very infrequently, often several million years apart. Eventually, erosion breaks the volcano back down to sea level where it becomes an atoll (coral atoll stage). Because atolls are the growth of coral and marine organisms, when the Pacific Plate carries the atoll to waters too cold for these organisms to survive, they erode away into seamounts and