geomorphology & earth landforms section 2 MCQ Questions & Answers Detailed Explanation

Answer: (c)

Answer: (b)

Highly viscous lava tends to entrap gas, which forms vesicles (bubbles) within the rock as they rise to the surface. Lava with low viscosity tends to easily release bubbling gases as they are formed.

Lavas also may contain many other components, sometimes including solid crystals of various minerals, fragments of exotic rocks known as xenoliths and fragments of previously solidified lava. Volcanic eruptions are caused by magma (a mixture of liquid rock, crystals, and dissolved gas) expelled onto the Earth’s surface.

At depth in the Earth, nearly all magmas contain gas dissolved in the liquid, but the gas forms a separate vapour phase when pressure is decreased as magma rises toward the surface of the Earth. This is similar to carbonated beverages which are bottled at high pressure. The high pressure keeps the gas in the solution in the liquid. Gas gives magmas their explosive character because the volume of gas expands as pressure is reduced.

Answer: (c)

Chambal ravine formation significantly increases soil loss from agricultural lands and severely impacts agricultural productivity. A review of ephemeral gully erosion and spreading rates of the ravenous tracks of Lower Chambal Valley using geospatial tools shows that both the ravenous and the marginal lands have increased during the last 15 years.

Answer: (b)

The Andes Mountains of South America are a result of a convergent plate boundary, also known as a destructive plate boundary.

It is an actively deforming region where two tectonic plates or fragments of the lithosphere move toward one another and collide.

Answer: (b)

A rift valley is a linear-shaped lowland caused due to the fissure in the earth along which one side moves down with reference to the other. It is commonly seen between several highlands or mountain ranges created by the action of a geologic rift or fault.

A rift valley is formed on a divergent plate boundary, a crustal extension, a spreading apart of the surface.

Answer: (d)

Igneous rock (derived from the Latin word ignis meaning fire) is one of the three main rock types, the others being a sedimentary and metamorphic rock.

Igneous rock is formed through the cooling and solidification of magma or lava. Igneous rock may form with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.

This magma can be derived from partial melts of pre-existing rocks in either a planet’s mantle or crust. Typically, the melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition.

Granite is the best-known igneous rock. Many people recognize granite because it is the most common igneous rock found on Earth’s surface and because granite is used to make many objects that we encounter in daily life.