(a) What is volcanic intrusion ? (b) Describe the characteristics and mode of formation of a block mountain. (c) List three landforms that are associated wi...

Answer Details

(a) Volcanic intrusion is the process by which molten rock (magma) is injected into pre-existing rocks, solidifies and forms an igneous rock mass.

(b) A block mountain is a type of mountain that is characterized by steep, uplifted blocks of rock that are bounded by faults or fractures. These blocks are usually composed of hard and resistant rocks that have been pushed up or uplifted by tectonic forces. Block mountains are formed when large blocks of rock are uplifted and tilted along fault lines, creating a series of steep escarpments and ridges.

(c) Three landforms that are associated with intrusive volcanic activities are:

• Batholiths: These are large, irregularly shaped masses of intrusive igneous rock that are exposed over an area of at least 100 square kilometers. They are formed when large volumes of magma solidify beneath the Earth's surface and are exposed after millions of years of erosion and uplift.
• Dikes: These are tabular, sheet-like intrusive bodies of igneous rock that cut across the layers of pre-existing rock. They are formed when magma is injected into fractures or cracks in the surrounding rock and solidifies, forming a vertical or steeply inclined wall-like structure.
• Sills: These are sheet-like bodies of intrusive igneous rock that are parallel to the layers of pre-existing rock. They are formed when magma is injected into horizontal cracks or bedding planes in the surrounding rock and solidifies, forming a flat or gently sloping layer of igneous rock.