I mentioned a while back that I was going to do a cheat sheet on Volcanoes since I had a stage in my son’s development where all he wanted to talk about was Volcanoes and more specifically, Pompeii. Today, that’s right, I’m going to give you a quick cheat sheet on Volcanoes.
When it comes to Volcanoes, it can be pretty simple to explain them. They are, after all, mountains that spew lava, right?
In many ways that answer is yes, but not all volcanoes are mountains, in the exact sense of the word, and not all mountains are volcanoes.
Volcanoes are usually formed at the spots where platelets either collide or pull apart. Generally, there is a gap where the plates border each other and a lake of molten rock is trapped in the space between the platelets. This is called a magma chamber if you were to look at a volcano. Once the magma collects in the chamber, a series of eruptions will occur. Each time it erupts, the lava and ash that comes out of the eruption cools and begins to form a pile of igneous rock. With each passing eruption, more height is added to the pile and eventually it begins to form a mountain. This process can take thousands of years and some volcanoes can become extinct before they even gain significant height.
Volcanoes can also form at hot spots, such as those found in Hawaii, which are found above a feeder channel, or magma plume, that feeds magma from the Earth’s core up into a chamber in the Earth’s crust. The last place a volcano can form is over thin spots in the Earth’s crust.
Since the platelets of the Earth are constantly moving, volcanoes can and do become extinct. An extinct volcano occurs when the platelets have moved far enough from the magma plume that it is no longer attached to it. In the case of the Pacific Ring of Fire, you will find many volcanoes that are now dormant, no longer attached to the magma plume that created it. However, when it shifted, a new volcano began to form over the magma plume and the cycle was begun again.
There are several types of Volcanoes and I’m not going to get into the definition for each one since this is after all a cheat sheet. I don’t want to load you down with too much information but I have added a link that will explain each one to you in more depth.
The types of Volcanoes are:
When a volcano erupts, there are two types of flow. These are the Dome Collapse where there is a thick crust of lava that blocks the top of the volcano shaft. When the lava reaches the blockage, it begins to flow sideways out of the top of the volcano. The second is the Collapsing Vertical Eruption where the eruption forces volcanic ash and other objects up into a cloud before it collapses and begins to flow down the sides of the volcano.
Lastly, there are several types of eruptions and these are:
And that is all I am going to go into about volcanoes, although I could go into much more. If you would like more information on Volcanoes, I suggest using the wikipedia site on Volcanoes or going to the site, Volcano World. This is a great site that has a section for teaching and a section for Kids. One of the books that I used for a lot of my research on volcanoes was a Visual Dictionary that I bought for my class and then brought home. If you have a chance to find a good visual dictionary for kids, don’t hesitate to pick it up.
-Sirena Van Schaik
