Formation Of Hawaiin Islands Essay Research Paper

Formation Of Hawaiin Islands Essay, Research Paper

The Formation of the Hawaiian Island Chain

The Hawaiian Islands are one of the most beautiful and popular island chains in the world. Millions of tourists visit the islands every year to experience the great treasures that they have to offer. People see Hawaii as an ideal vacation spot for many reasons including; a year round tropical climate, the lush vegetation, and the numerous black sand beaches. However, the Hawaiian Islands are not only pretty to look at. The Islands possess unique geological aspects that make it possible for the islands to have these desirable characteristics. The Hawaiian Islands were not pieces of a continent that drifted out to sea, but were actually created by volcanoes in the middle of the Pacific Ocean. The process in which this chain of island is formed is quite intriguing and complex. The different steps include the presence of a hot spot, the emergence of an oceanic volcano, the plate tectonics of the region, the submergence of the older volcanoes, and the dynamics of the active Hawaiian volcanoes.

Hawaii consists of many volcanoes that were produced by a feature known as the Hawaiian hot spot. A hot spot, or plume, is a large column of magma, molten lava, which rises from deep within the Earth s asthenosphere (Monroe 332). The magma that comes out of these columns is so hot that it can melt through the layer of earth on top of the asthenosphere, called the mantel, and through the Earth s crust (the top layer of the Earth). There are only forty known hot spots that exist today. Hot spots can be found under a continent or an ocean, at a mid-ocean ridge and even in the center of a plate, like the Hawaiian hot spot (Duxbury 78). Each hot spot channels hot material at its own unique time intervals. Hot spots are generally stationary, however; their positions may change slightly. A typical hot spot has a life span of about ten million years (Duxbury 78). They are great sources of new material for the Earth s crust and can create, not only one, but a chain of islands.

The emergence of an oceanic volcano is only the beginning of an island chain. When a hot spot is active it will push magma up to the crust above, to create a volcanic peak if on land, or seamount if in water. The primary volcanoes on each of the Hawaiian islands are called shield volcanoes. They are described as gently slopping mountains, looking much like the outer surface of a shield lying on the ground. They are created by numerous lava flows that slowly spread out and harden in very thin layers (Rubin 1). After the building of layer upon layer the volcanoes eventually cut through the surface of the ocean forming an island (Rubin 2). The eruptions of shield volcanoes tend to have a quiet, smooth outpouring of thick, flowing magma rather than a sudden explosion (Duxbury 73). However, on occasion, some of the Hawaiian volcanoes, such as Kilauea, have produced large explosions. Explosions usually only occur when the magma mixes with groundwater, creating instant vaporization. Some of Hawaii s shield volcanoes have lava fountains that spew up from the top of the volcano that can reach as high as 400 meters (Monroe 89). The average Hawaiian volcano can remain active for hundreds of thousands of years before being carried away from its hot spot by the moving pacific plate (Rubin 2). The volcanic activity within the sea around the islands is believed to be a factor in the fact that the surrounding waters are about 83 degrees F year round.

The plate tectonics of the Hawaiian Island region play a major role in the formation of this unique island chain. As the hot spot forms and fuels a volcano, the pacific plate is continuously moving westward. Since hot spots are stationary the moving plate carries the volcano with it, cutting off the constant supply of magma. Without the magma reserve the volcano can no longer erupt, leaving it inactive. After the volcano is moved the hot spot will no longer have an outlet for magma. Soon after the plume will erupt once again and create a new volcano to replace the one it had just lost. As the pacific plate continuously moves across the Hawaiian hot spot consecutive eruptions have created the linear order of the islands. The plate moves over the asthenosphere northwest at a rate of 5 to 7 centimeters per year (Rubin 1). The age of the Hawaiian Islands tend to get older as they are observed from the southeast to the northeast (Rubin 2). In summary, when compared to an active volcano currently under the hot spot, the other volcanoes continue to drift westward while at the same time they are getting older. One of the northwestern most islands, Kauai, is estimated to be formed 3.8 to 5.6 million years ago, whereas Hawaii, the island currently under the hot spot, began forming less the one million years ago (Monroe 102). The land features of the different islands also tell a tale of their ages. The island of Hawaii shows little signs of erosion. On the other hand, an older island, like Oahu, exhibits many signs of erosion caused by their continuous movement as well as elements like wind and rain. The creation and the motion of the Hawaiian Island chain are a very useful tool in helping geologists to explain the movement of the pacific plate.

The submergence of old volcanoes is another part to the cycle of island chains. As the islands move away from the hot spot the plat