The landforms formed by internal volcanic activities are mostly basaltic lava flows, which are created when lava erupts from within the earth. Basaltic lava is a type of lava that has a low viscosity and flows easily downslope, creating large sheets of rock that can extend for miles. The sheets of basaltic lava can be up to several miles wide. The most common types of internal volcanic activities include pyroclastic flows, lahars and avalanches.
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Following are some Major Landforms formed by volcanic actions
Volcanic cone
The material that comes out of the volcano accumulates around the mouth, which takes the form of a cone-like base, it is called a volcano cone. There are many types of cones on the basis of their size, extent, and composition, in which the following are notable.
1. Lava Cones: These cones are formed by the eruption of an erupting volcano. They are formed by lava flow. They do not have boulders. According to the composition, their shape also varies, some of which are famous.
Acid lava cones are formed from more sand-mixed lava. Their form is a dome with a sharp slope. Supersilicic lava cones are formed from mixed lava with low mass. This lava is very liquid and thin, so it spreads over a large area. In this, the slope of the cone is slow.
2. Cinder Cones: These are formed by the eruption of an erupting volcano. There are more rocks in these. They also have high ash content.
Their shape is that of a perfect cone. Their edges are convex and sloping. According to the ash and ember, they have an angle of friction. Ash rests on 300 and embers rest on 450.
3. Mixed Cone: It is formed by explosive and peaceful eruptions. In these, one layer after another of rock, boulders, and lava is formed. Hence it is also called Straya Cone. The best examples of this are the Mayans of the Philippine Islands and the Fujiyama of Japan.
4. Slope Cone- It is formed by the deposition of fast-moving lava. Due to the rapid flow of lava, the areas of the cone widen, and parallel folds are formed around the mouth. They are low in height and ‘they appear like plateaus with simple slopes.
5. Stopper Dome Cone – This cone is formed by the accumulation of glutinous episodic magma near the volcano. In these, the magma rises over the previously collected magma and the dome continues to grow. In this, the hard part gets divided into pieces and the cell debris is formed around the dome.
6. Dependent cones – Cone walls of compound cones are often broken in the explosion and many holes are formed on their sides. In these cracks, small ash cones form in a line all around the edge. This gives a strange shape of a cone. These are called dependent cones.
7. LavaLav Cones – Narrow gas streams of lava flow through dependent cones. If there is a gradual eruption, the lava emanating from it is ephemeral. The gas bubbles of lava break up to form a sharp sloping horn shape. This conical shape is called lavalav cone.