geomorphology & earth landforms section 2 Practice Questions Answers Test with Solutions & More Shortcuts

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)

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.