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Consider the following statements regarding Volcanic Cones : 1. During volcanic eruptions, acid lava cones are formed by highly viscous lavas. 2. Viscous lavas have high mobility and can travel for long distances. 3. Acid lavas result in the formation of high cones with steep slopes. 4. Composite cones are the highest volcanic cones. Which of the statements given above are correct ?
Explanation
Statement 1 and 3 are correct: Acid lavas are highly viscous because they have a high silica content. Due to this high viscosity, they do not flow far from the vent, cooling quickly and solidifying to form steep-sided, high volcanic cones.
Statement 2 is incorrect: Viscosity refers to a fluid's resistance to flow. Therefore, highly viscous lavas have low mobility and cannot travel long distances. In contrast, basic (basaltic) lavas have low viscosity, high mobility, and form flat shield volcanoes.
Statement 4 is correct: Composite cones (stratovolcanoes) are built from alternating layers of lava and pyroclastic materials (ash, cinder). They are characterized by their large size, symmetrical shapes, and are generally the highest and most prominent volcanic peaks on Earth, such as Mt. Fuji and Mt. Mayon.