Prof: Volcanoes Volcanoes are points of weaknesses on the earth’s crust or outer skin, where gas as well as hot and melted rock from the inner parts of the earth can burst open to the surface or has done that before (Green 4). Volcanoes take various forms, shapes, and sizes, implying that some are steep sided and tall while others are simply cracks in the surface of the ground (McKay, What Are Volcanoes? 1). The first section of this definition implies that volcanoes can be mere openings on the crust of the planet that do not even have lava.
Where Volcanoes Occur
Although volcanoes appear to occur in every part of the world, they do not just erupt blindly, but in red triangles. They occur in clusters and linear chains all over the world. Regardless of few exceptions to this rule, most take place in lines that are curved, as opposed to circular ones. The two common patterns that they form called the ring of fire and the mid-ocean ridges (Oxlade 12).
Plate tectonics explain the movement of plates around the earth but are different from continental drift. They elucidate why ocean basins are in existence. The earth’s crust, according to the theory of tectonics, occurs in two forms: continental crust and oceanic crust. The latter is rigid, dense, and brittle as opposed to continental crust. It breaks into separate slabs also known as plates (McKay, Plate Tectonic Settings 1). On the other hand, many rocks that have conjoined over billions of years or geologic time make the continental crust. They are less dense, and can deform or change much easier explaining their complication and uncertainties. Summing it all up, hot gases and material emanate from the mid-oceanic ridges while cool material goes down at subduction areas, and it is at the plate boundaries that volcanoes take place (McKay, Subduction Zones 1).
Reasons for Eruption
Volcanoes erupt as fresh magma from the center of the earth rises up through weak areas or zones and consequently reaching the crest of ridges to develop novel oceanic crust. This process referred to as seafloor spreading, took place many years ago, and it led to long mid-oceanic system of ridges (McKay, The Basics of Plate Tectonics 1).
Review of site
The website, blackboard learn, is a modernized platform that offers easy access, navigation, organization, and illustration of learning material. The site’s contents are well organized, and students can easily follow the direction of the course without supervision, assistance, or any trouble. What makes the educational portal even better is the systematic organization of classes into weeks, which offers an easier way of following through lectures and assignments. Further, the site enhances further learning by offering multimedia material such as pictures and videos, which are highly beneficial. Moreover, the getting started, syllabus, announcements, and discussion board tabs are beneficial in enhancing the learning experience.
The site has explained grey areas of geology, and I have learnt key things about volcanoes: what they are, how they occurred, why they occurred, and the forces behind the volcanoes. Initially, I used to think that volcanoes simply erupted anywhere provided molten lava was boiling underneath the surface waiting to come out. However, the site has disillusioned me, and I now know that there is a special mechanism that volcanoes followed, and that they exist in certain red regions across the globe.
Green, Jen. Volcanoes Around the World. The Rosen Publishing Group, 2009. Print.
McKay, Daniele. Plate Tectonic Settings. University of Oregon Blackboard. N. p., 2014. Web. 5 Apr. 2014.
—. Subduction Zones. University of Oregon Blackboard. N. p., 2014. Web. 5 Apr. 2014.
—. The Basics of Plate Tectonics. University of Oregon Blackboard. N. p., 2014. Web. 5 Apr. 2014.
—. What Are Volcanoes? University of Oregon Blackboard. N. p., 2014. Web. 5 Apr. 2014.
Oxlade, Chris. Earthquakes amp. Volcanoes. Black Rabbit Books, 2004. Print.