Highlight the main features and mode of formation of any two of the following landforms: Composite cone (Stratovolcano), Rift valley

Here is the answer for Question 2 from Section C.

Question 2:

a). Highlight the main features and mode of formation of any two of the following landforms:

• i. Composite cone (Stratovolcano)

  • Main Features: Composite cones are characterized by their steep, symmetrical slopes and a conical shape. They have a central crater at the summit. Their structure is built up of alternating layers of viscous lava flows and pyroclastic material (ash, cinders, volcanic bombs), giving them their layered appearance.
  • Mode of Formation: They form at convergent plate boundaries where an oceanic plate subducts beneath a continental or another oceanic plate. The subducting plate melts, forming magma that rises to the surface. Eruptions are typically explosive, due to the high viscosity of the magma and trapped gases. Each eruption adds a new layer of lava or ash, gradually building up the cone over many thousands of years.

• iii. Rift valley

  • Main Features: A rift valley is an elongated, narrow depression or trough in the Earth's crust. It is typically bounded by steep, parallel fault scarps (cliffs) on both sides. The floor of the valley can be relatively flat or contain lakes and volcanoes.
  • Mode of Formation: Rift valleys form in areas where the Earth's crust is subjected to tensional forces, causing it to stretch and thin. This stretching leads to the development of parallel normal faults. The block of land between these faults then subsides or drops down relative to the blocks on either side, creating the characteristic valley. This process is often associated with divergent plate boundaries or continental rifting, where plates are pulling apart.

b). State any five benefits of volcanic activity to man

• i. Fertile soils: Volcanic ash and weathered lava provide rich, nutrient-dense soils that are excellent for agriculture.
• ii. Geothermal energy: Heat from magma close to the surface can be harnessed to generate electricity, providing a renewable energy source.
• iii. Mineral deposits: Volcanic processes bring valuable minerals (e.g., gold, silver, copper, sulfur) to the Earth's surface, which can be mined.
• iv. Tourism: Volcanic landscapes, hot springs, geysers, and volcanic lakes attract tourists, boosting local economies.
• v. Building materials: Volcanic rocks like basalt and pumice are used as construction materials.