Land Feature Hawaii
Sherra L. Sharpe
GLG/150
June 27, 2016
Kathryn Schubel

Abstract

Land Feature Hawaii
Plate tectonics is the study of what causes the Earth’s movements. The theory of plate tectonics breaks down the exact functions of the lithosphere and the asthenosphere as it relates to how the Earth rotates. The outer layer of the mantle which is a rocky crust it what makes up the lithosphere plates. These lithospheric plates sit on a layer of Earth called the asthenosphere. The asthenosphere is a very hot weak layer that has a continuous movement. In plate tectonics there is a condition known as isostasy that works between the lithosphere, and the asthenosphere. What happens during this process is the lithosphere is basically floating on top of the asthenosphere, because the temperature is close to melting.
One of the main influences of the Hawaii volcanoes is the fact that it sits on the Pacific plate the largest tectonic plate on the planet. As the sea floor spreads it causes the plate to continue to widen as well. That has the biggest impact of the growth of the Hawaiian Islands. Another key factor that not influences location, but the intensity is the changes in sea level. When the sea level began to change that made a decrease in the shorelines, so there was more land being submerged under water. The eruption of volcanoes in Hawaii is what influences an Earthquake. According to scientist Earthquakes are common after a volcano has erupted.
The Hawaii was formed by a convergent margin of oceanic lithosphere plates. These plates join and on occasion can create a volcano. They can also be made in the middle of the plate where there is magma. If the magma erupts and hit the sea floor that is called a hot spot. A hot spot in the center of the Pacific plate is what formed the Hawaiian Islands. As the plate continued to move over the hot spot more islands were form. There are a total of 132 islands known as the Hawaiian Island chain. The eruption of those volcanoes left some parts of Hawaii looking like the desert, while other places hot lava made deep canyons on the island. The largest mountain on Earth is Hawaii’s Mauna Loa, and was formed over times as the volcanoes continued to erupt. The flow of the lava is how it reached its height.
The history of Hawaii tells us that the sacred home of Pele the volcano goddess was Kilauea and the Halema’uma’u caldera. It was said that the Hawaiian people would go to the crater to offer Pele gifts. Then in 1790 as a group of warriors leading women, and children across the crater it erupted. Historians say that this particular eruption was more violent that it normally was. Several of the men, women, and children lost their lives, while others left footprints. That you can still presently see in the lava now. A few years ago on March 19, 2008 Halema’uma’u crater exploded for the first time since 1924. It was also the first eruption of Kilauea caldera since September 1982. There was no lava released during the explosion, however the debris did scatter across 74 acres of land. One community did report having a little ash as a result of the eruption. The explosion did leave the Halema’uma’u damaged, and cover some of Crater Rim Drive. Scientist believed that happened because of a hydrothermal gas.
There are several rocks that are created from the eruptions of volcanoes in Hawaii; however I only wanted to focus on three in particular. The first of those rocks has been named the Bomb. The Bomb received its name because it is thrown in the air. It is made of molten pieces of lava that form a round shape due flying in the air. The next rock is the Andesite, and it gets its name from the Andes Mountains. They tend to be black and gray in color, and usually have plagioclase crystal in them which is a mineral. The Andesite’s are very rare in Hawaii where they can only be found in Mauna Kea and Haleakala. The last rock is the Obsidian, and it has a high economic value. It is made out of lava that is not so common by the name of silica-rich rhyolite found in Hawaii. Obsidian lava cools down fast leaving the crystals small, because they don’t have time to grow. They are a shiny curved rock that is normally black in color, but can be brown, green, and tan. The rarest of the Obsidian colors are blue, orange, red, and yellow along with a swirled black/brown.
The economic value of the Obsidian is so great due to its many uses. They are most commonly used to make arrow heads, and knife blades. One of the more important uses of this rock is making surgical scalpels, because of its superior performance over regular surgical steel. It is said that scalpels made from Obsidian are more precise. Obsidian is very popular when it comes to making jewelry. It best used in the making of earrings and pendants, because they are low-impact. There are some artists who also prefer to use Obsidian as it is so easy to carve and cut. Obsidian is one of the most mined rocks, because of the many uses that it has.

Reference Page: https://phoenix.vitalsource.com/#/books/9781119140085/cfi/6/30!/4/2/4/16/12/12/4/6@0: http://geology.com/rocks/obsidian.shtm http://www.soest.hawaii.edu/GG/HCV/haw_formation.html http://www.instanthawaii.com/cgi-bin/hi?Volcano.types http://oceanservice.noaa.gov/facts/hawaii.html http://www.tulane.edu/~sanelson/Natural_Disasters/volclandforms.htm