Guide to Volcanoes
Volcanoes in simple terms may be defined as an opening in the earth's surface from which molten lava and other gases are produced. Around 80% of our earth's surface has come from the Volcanoes. In fact, the surface of the sea and mountains were formed by countless volcano eruptions, and the atmosphere was formed by the gases produced during the eruption.
Formation of Volcanoes
Our earth is very hot and contains a liquid called Magma that runs inside the earth. Its heat can be figured out by the fact that it can melt steel as well. Now sometimes, magma starts building pressure and moves up to the surface of the earth. Its pressure makes it rise up to the surface of the ground, thus forming a mountain. If the liquid comes out from the formed mountain, then a Volcano is formed.
Magma might come out of the top of volcanoes or bubble very slowly from a crack in the ground. When magma comes out of the fissure or crack it is called lava. However, in most cases, only smoke or gases come out from the volcano.
Active volcanoes can be found in various areas. Though they don't erupt often, running lava and series of ashes can emit from them. Active volcanoes can have different shapes: they can be low and flat, short and large, or have pointed cones because of very thick lava.
As for inactive volcanoes, those are volcanoes which have been quiet for a long time, and nothing has come out from their tops.
Near volcanoes, you will be able to find hot water springs. If you're wondering why they're hot, that is because of the heat produced by molten magma.
Sometimes, rocks can be found near volcanoes, and that indicates that there is an old volcano near this location. Mostly in ancient areas of volcanoes, different types of volcanic rocks are found. Volcanic rocks can be very colorful, for e.g. reddish black, purple, blue, and yellow and black. Some of them are shiny like glass, while some are made from ash, thus are mostly dull and powdery.
Types of Volcanoes
Volcanoes generally fit into six categories:
1. Shield Volcanoes - Volcanoes give a large amount of lava that can build a mountain with a shield-like profile. Some examples can be seen in Hawaii and Iceland.
2. Cinder Volcanoes - They are those volcanoes which give out small pieces of scoria and other types of cinder. They erupt shortly, and usually one cone erupts at a time. Some places where these can be found include Mexico and Arizona.
3. Strato Volcanoes - They are tall volcanoes that are made of lava and other volcanic particles. They are also called composite volcanoes, and are typically found in Japan and the Philippines.
4. Submarine Volcanoes - These volcanoes are very active and are present in shallow waters. They usually blast debris and rocks near the surface of water.
5. Sub-glacial Volcanoes - These volcanoes are developed under ice caps. When the ice melts, the lava on top collapses and releases as pressure. This type of volcano is also called Table Mountains, and can be found in British Columbia and Iceland.
6. Super Volcano - this is the most powerful type of Volcano and usually has very enormous eruptions. It can take many years to cool down this volcano down once it has erupted. That is why people in New Zealand and Indonesia are always worried.
Related Teacher Resources That Are Worth A Look:
- Activity Report (Weekly)
- Cake Batter Lava
- Gelatin Volcanoes
- How to Make a Volcano
- How to Make a Volcano Model
- How Volcanoes Work
- Lava Layering
- The Impact Volcanic Eruptions
- Volcano WebQuest
- Volcanoes and the Ring of Fire