Geomorphology MCQs for UPPSC (UP) Exam

Marble is hard, used in our homes, so it cant be sedimentary rock.
Regarding Slate,
It is made up of shale, which is a sedimentary rock.

Explanation:

Pole fleeing force is a term used to describe the outward-directed force associated with the spinning of the Earth. This force is also known as centrifugal force. It is the force that causes objects at or near the Earth's equator to experience a slight outward push. This force is due to the rotation of the Earth on its axis.

The centrifugal force is a result of the Earth's rotation, which causes the equator to bulge outwards slightly and the poles to flatten slightly. It is important to note that the pole fleeing force is not responsible for the bulging at the Earth's poles, which is primarily caused by the Earth's rotation and the gravitational pull of the Sun and Moon.

The pole fleeing force is an important factor to consider when studying the Earth's rotation. It influences the Earth's shape, the distribution of mass within the Earth, and the motion of the Earth's oceans and atmosphere.

Conclusion:

In summary, the pole fleeing force is the outward-directed force associated with the spinning of the Earth. It is not responsible for the bulging at the Earth's poles but is an important factor to consider when studying the Earth's rotation.

Oldest Rocks in the World

The oldest rocks in the world are found in Western Australia.

Evidence

- The rocks in Western Australia are known as the Jack Hills group and have been dated to be 4.4 billion years old.
- These rocks were formed during the Hadean Eon, which lasted from the formation of the Earth around 4.6 billion years ago to the beginning of the Archean Eon around 4 billion years ago.
- The rocks contain tiny zircon crystals which have been used to determine their age.
- The zircon crystals have been found to be up to 4.4 billion years old, making them the oldest known rocks in the world.

Importance

- The discovery of these rocks in Western Australia has important implications for our understanding of the early Earth.
- It suggests that the planet was able to cool and solidify much faster than previously thought.
- It also suggests that conditions on the early Earth were more hospitable for life than previously thought, as life is believed to have emerged around 3.5 billion years ago.

Conclusion

In conclusion, the oldest rocks in the world are found in Western Australia and are known as the Jack Hills group. These rocks have been dated to be 4.4 billion years old and contain tiny zircon crystals which have been used to determine their age. The discovery of these rocks has important implications for our understanding of the early Earth and the emergence of life.

Properties of Limestone, Chalk, and Dolomite

Limestone, chalk, and dolomite are three different forms of calcium carbonate. Let's understand the properties of each form of calcium carbonate mentioned in the given statements.

1. Limestone:
- In its pure state, limestone is made up of calcite or calcium carbonate.
- It is a sedimentary rock that is formed over millions of years by the accumulation of shells, corals, and other marine debris.
- Limestone is used as a building material, as a raw material for cement production, and as a source of calcium for agriculture.
- When magnesium is also present in limestone, it is called dolomite.

2. Chalk:
- Chalk is a very pure form of limestone that is white and rather soft.
- It is composed of microscopic shells of plankton that lived in the sea millions of years ago.
- Chalk is used for writing, drawing, and as a filler in paint, plastics, and other materials.

3. Solubility of Limestone:
- Limestone is soluble in rainwater, which, with carbon dioxide from the air, forms a weak acid.
- This acid reacts with the calcium carbonate in limestone and dissolves it, forming calcium bicarbonate.
- Over time, this process can create sinkholes and other features in limestone landscapes.

Conclusion:
From the above properties of limestone, chalk, and dolomite, we can conclude that all three statements given in the question are correct. Therefore, the correct answer is option 'D' - All of the above.

Introduction:
The given statements are related to the impact of glacial activity on lakes and agricultural development. Let us analyze each statement and its correctness.

Statement 1: Morainic deposits may dam, or glaciers may hollow out, lakes which greatly inconvenience large-scale farming or land development.
- Glaciers are massive bodies of ice that move slowly under their own weight. As they move, glaciers can create various landforms, including lakes.
- Morainic deposits are accumulations of rocks, soil, and other debris carried and deposited by glaciers.
- Glaciers can hollow out lakes by eroding the land and creating depressions or basins.
- Alternatively, when glaciers retreat or melt, they can leave behind morainic deposits that dam natural drainage systems, resulting in the formation of lakes.
- These lakes can greatly inconvenience large-scale farming or land development as they occupy valuable land and restrict agricultural activities.

Statement 2: But when the lakes are eliminated, the old glacial lake beds with their rich alluvium support heavy cropping.
- When the lakes formed by morainic deposits are eliminated, the old glacial lake beds are exposed.
- These lake beds are typically composed of rich alluvium, which is a fertile soil deposit made up of sediment carried and deposited by water.
- The alluvial soil in the old glacial lake beds is highly fertile and suitable for agriculture.
- The presence of alluvium supports heavy cropping, meaning that large-scale agricultural activities can be carried out on these lands.

Correctness of the statements:
- Statement 1 is correct as glaciers can either dam lakes through morainic deposits or hollow out lakes through erosion, which can inconvenience large-scale farming or land development.
- Statement 2 is also correct as the elimination of lakes formed by glaciers exposes the old glacial lake beds, which are rich in alluvium and support heavy cropping.

Conclusion:
Both statements 1 and 2 are correct. The formation of lakes by glacial activity can hinder agricultural development, but the elimination of these lakes exposes fertile alluvial soil that supports heavy cropping.

Salient Features of Fold Mountains

Fold mountains are formed by the folding of the Earth's crust. They are characterized by certain salient features, which are discussed below.

1. Conical Peaks:
Fold mountains are most likely to have conical peaks due to the volcanic activity associated with them. The magma below the surface rises and solidifies to form a cone-shaped structure.

2. Vertical Displacement:
Fold mountains are created when large areas of the Earth's crust are broken and displaced vertically, leading to the formation of fold structures.

3. Associated Volcanism:
Fold mountains are often associated with volcanism, either from the mountain core or its vicinity. This is due to the movement of tectonic plates, which leads to the formation of magma chambers and volcanic eruptions.

Correct Option
None of the above statements is correct as the first statement is incorrect. Fold mountains are most likely to have conical peaks due to the associated volcanic activity.

Sandstone is a sedimentary rock formed by sedimentation of sand grains.

Explanation:

Alpine mountain building phase is the recent phase to which the Himalayan mountains belong to. The Ural Mountains were not formed during the Alpine orogeny (mountain building phase).

Therefore, the correct answer is option 'A' - 1 only.

- Alpine Mountain Building Phase
The Alpine mountain building phase is the most recent phase and began about 40 million years ago. This phase is ongoing and still forming mountains today in areas such as the Himalayas, the Alps, and the Andes.

- Himalayan Mountains
The Himalayan Mountains are a range of fold mountains located in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. They were formed during the ongoing Alpine mountain building phase.

- Ural Mountains
The Ural Mountains are a range of fold mountains located in western Russia, separating Europe and Asia. They were formed during the Variscan orogeny, which occurred about 300 million years ago, and not during the Alpine mountain building phase.

Therefore, statement 1 is correct, and statement 2 is incorrect.

Himalayan region and its poor mineral resources

There are several factors that contribute to the Himalayan region being poor in mineral resources. However, the most significant reason is the complex rock structure in the region.

Complex rock structure

The Himalayan region is characterized by a complex geological history, resulting in the formation of diverse rock types and structures. The region is mainly composed of metamorphic and sedimentary rocks, which are less likely to contain significant mineral deposits compared to other types of rocks such as igneous rocks. Metamorphic rocks are formed through the transformation of pre-existing rocks under high pressure and temperature conditions, which often leads to the loss of mineral resources.

Unfavorable terrain and adverse climatic conditions

While the undulating terrain and adverse climatic conditions in the Himalayan region certainly pose challenges for mineral exploration and extraction, they are not the primary reasons for the region's poor mineral resources. These factors may make it difficult to access certain areas and conduct mining operations, but they do not directly impact the presence or absence of mineral resources in the region.

Crystalline rocks and mineral resources

The statement mentioned that the Himalayan region is made up of crystalline rocks, which do not hold mineral resources anywhere in India. This is incorrect. Crystalline rocks can indeed contain mineral resources, although their presence and abundance vary from region to region. Crystalline rocks, such as granite and gneiss, can host valuable minerals such as gold, silver, copper, and tin. However, in the case of the Himalayan region, the primary reason for the lack of mineral resources is the complex rock structure rather than the presence of crystalline rocks.

In conclusion, the Himalayan region's poor mineral resources can be attributed to its complex rock structure, which is dominated by metamorphic and sedimentary rocks. While other factors such as unfavorable terrain and adverse climatic conditions might pose challenges for mineral extraction, they are not the main reasons for the region's limited mineral resources.

Exfoliation refers to the peeling or shedding of rock layers due to the weathering process. It is a geological phenomenon that occurs in various environments, including deserts. Exfoliation occurs primarily as a result of mechanical weathering, which involves the physical breakdown of rocks without any chemical changes.

Mechanical Weathering:
Mechanical weathering is the process by which rocks are broken down into smaller fragments without any chemical alteration. It is primarily driven by physical forces such as temperature changes, pressure variations, and the action of water, wind, or ice. Exfoliation is one of the outcomes of mechanical weathering.

Process of Exfoliation:
Exfoliation occurs when rocks undergo expansion and contraction due to temperature fluctuations. During the day, rocks are exposed to high temperatures, causing them to expand. At night, the temperature drops, and the rocks cool down, leading to contraction. These repeated cycles of expansion and contraction result in stress being built up within the rocks.

As the stress accumulates, the outer layers of the rock start to detach from the underlying layers, leading to the formation of fractures or cracks. Over time, these cracks propagate parallel to the surface, causing the outer layers of the rock to peel or flake off. This process is similar to the peeling of an onion, where successive layers are shed.

Factors Affecting Exfoliation:
Several factors influence the rate and extent of exfoliation. These include:
1. Rock Type: Some rocks are more susceptible to exfoliation than others. For example, granite, a common rock found in many mountainous regions, is prone to exfoliation due to its mineral composition and structure.
2. Climate: Temperature variations play a crucial role in exfoliation. Regions with large diurnal temperature ranges, such as deserts and high-elevation areas, are more prone to exfoliation.
3. Jointing: The presence of pre-existing joints or fractures in the rocks can enhance the process of exfoliation as they provide pathways for the cracks to propagate.
4. Erosion: Exfoliation can be accelerated by erosion processes such as wind, water, or glaciers. These agents remove the overlying material, relieving the confining pressure on the rocks and promoting exfoliation.

Conclusion:
Exfoliation is a natural process that occurs due to mechanical weathering, specifically the repeated expansion and contraction of rocks caused by temperature fluctuations. It leads to the peeling or shedding of rock layers, resulting in the formation of characteristic rock formations such as domes, tors, and exfoliation sheets. While exfoliation can occur in various environments, including deserts, it is not synonymous with the carrying away of topsoil by wind or the cracking of rocks into small pieces.

Continental Drift Theory

The correct answer is option C, Continental Drift Theory. This theory, proposed by Alfred Wegener in the early 20th century, suggests that the continents were once joined together in a single supercontinent called Pangaea and have since drifted apart.

Key Points:

1. Belt of Ancient Rocks:
The belt of ancient rocks from the Brazil coast that matches those from western Africa is evidence of the existence of a supercontinent. The similarities in the rock formations indicate that these regions were once connected.

2. Matching Ancient Rocks:
The age and composition of the rocks found along the Brazil coast and western Africa are similar, suggesting a common geological history. This similarity supports the idea that these two continents were once part of the same landmass.

3. Earliest Marine Deposits:
The presence of Jurassic age marine deposits along the coastlines of South America and Africa further supports the Continental Drift Theory. The discovery of similar fossils and sedimentary layers in both regions indicates that they were once adjacent and shared the same marine environment.

4. Pangaea:
According to the Continental Drift Theory, approximately 200 million years ago, all the continents were connected as one supercontinent called Pangaea. Over time, Pangaea began to break apart, and the continents we know today gradually drifted to their current positions.

5. Plate Tectonics:
The movement of the continents is explained by the theory of plate tectonics, which states that the Earth's lithosphere is divided into several large plates that float on the semi-fluid asthenosphere below. These plates move and interact with each other, causing various geological phenomena such as earthquakes, volcanic activity, and the drifting of continents.

Conclusion:

The presence of matching ancient rocks and Jurassic age marine deposits between the Brazil coast and western Africa provides strong evidence for the Continental Drift Theory. This theory explains how the continents have moved over millions of years and helps us understand the geological history and formation of the Earth's landmasses.

The Mid-Ocean Ridge system forms the most extensive chain of mountains on Earth, with more than 90% of the mountain range lying in the deep ocean - with a total length of about 60,000 km. Mid-ocean ridges are geologically important because they occur along divergent plate boundaries, where the new ocean floor is created as the Earth’s tectonic plates spread apart. As the plates separate, some molten rock rises to the seafloor, producing enormous volcanic eruptions of basalt, and building the longest chain of volcanoes in the world. Because most of these eruptions occur deep under the water, they often go unnoticed.