Circum-erosional/ Relict/ Residual Mountains form as a result of the residual part of an earlier mountain or plateau where rock erosion occurs, resulting in a flat and degraded area. Circum-erosional, relict, or residual mountains (Aravallis in India, Urals in Russia) are the remains of former fold mountains formed by denudation. Residual mountains can also form from river-cut plateaus that have been dissected into hills and valleys. This article will explain to you about Circum-erosional/ Relict/ Residual Mountains which will be helpful in Geography preparation for the UPSC Civil Service exam.

Circum-erosional/ Relict Mountains/ Residual Mountains

• Circum-erosional/Relict Mountains, also known as residual mountains or mountains of denudation, is a kind of landform formed through time as a result of the erosion of formerly high areas.
• Forces both inside and outside the globe can change the form of the planet's surface.
• Endogenic and exogenic forces may produce a wide range of landforms.
• A landform is a natural feature of the Earth's solid surface.
• Circum-erosional, relict, or residual mountains (Aravallis in India, Urals in Russia) are the surviving vestiges of ancient fold mountains formed by denudation (strip of covering).
• Residual mountains can also form from plateaus that have been carved into hills and valleys by rivers.
• The Highlands of Scotland, Scandinavia, and the Deccan Plateau are examples of dissected plateaus , where down-cutting streams have degraded the uplands into mountains of denudation.

Circum-erosional/ Relict Mountains

Circum-erosional/ Relict Mountains - Formation

• Residual mountains are erosion-type mountains formed over time by the slow disintegration of the mountain's exterior layer or surface layer.
• The majority of these mountains are solitary and lower in elevation than the most recently created mountains.
• These mountains can still be found in a number of locations.
• The most well-known are the Sierras de Europa in Spain and the Mesas in the United States.
• The Aravalli Mountains, Bihar's Parasnath Mountain, Tamil Nadu's Nallamala Hills, Odisha's Mahendragiri, the Veliconda Hills, Javadi Hills, Andhra Pradesh and Tamil Nadu's Palkonda ranges, and many others are instances of residual mountains in India.

Circum-erosional/ Relict / Residual Mountains - Characteristics

• Residual mountains are often considered "old" mountains.
• They are the remnants of once vast and possibly youthful mountain ranges or plateaus.
• Due to the prolonged erosion, these mountains usually have rounded features and less rugged topography than younger mountains.
• These mountains can be composed of a variety of rock types, but the most prominent peaks or features are often made of erosion-resistant rocks.
• Residual mountains can often stand as isolated peaks or small ranges amidst plains or plateaus, giving them a distinct appearance in the landscape.

Circum-erosional/ Relict Mountains - Significance

• Residual mountains are those that have been eroded by erosion forces such as winds, rain, snow, and flowing water. The hefty rocks that are left behind are known as residual mountains.
• Erosion affects the soils on the surface of mountains because it is a natural process of deterioration and transfer of soil particles.
• The top fine layer of soil on it is washed away by blowing winds and flowing water during rainstorms.
• The bedrock under this layer is then exposed, leaving the mountain looking stony and barren of vegetation.
• Though this stony surface is resistant to erosion, it can progressively deteriorate and dissolve over time.
• After a lengthy period of time, the height falls and the size shrinks.
• In general, residual mountains are the degraded mountains that remain after denudation.

Conclusion

Circum-erosional, relict or residual mountains are terms that refer to landforms that remain after extensive erosion processes have removed much of the original mountain mass or plateau. These mountains stand out in relief as they are surrounded by eroded plains or lowlands.

FAQs

MCQs

1. Which of the following is an example of a circum-erosional or relict mountain?

A) Himalayas
B) Andes
C) Aravalli Range
D) Rocky Mountains

2. What is the primary process responsible for the formation of residual mountains?

A) Volcanic activity
B) Tectonic folding
C) Erosion
D) Sedimentation

3. Which characteristic is typical of relict mountains?

A) Sharp, jagged peaks
B) Active volcanic activity
C) Rounded features and lower elevations
D) Formation through recent tectonic activity

4. Which of the following processes is least associated with the formation of residual mountains?

A) Wind erosion
B) Glacial erosion
C) Tectonic uplift
D) River erosion

5. The Urals in Russia are an example of which type of mountain?

A) Fold mountains
B) Block mountains
C) Volcanic mountains
D) Residual mountains

GS Mains Questions and Model Answers

Q1: Discuss the formation and characteristics of circum-erosional or relict mountains, providing examples from India.

Answer: Circum-erosional or relict mountains, also known as residual mountains, are landforms that remain after extensive erosion processes have removed much of the original mountain mass or plateau. These mountains stand out in relief as they are surrounded by eroded plains or lowlands. In India, the Aravalli Range is a prime example of a residual mountain range that has been shaped over millions of years by erosion and weathering. Relict mountains typically exhibit rounded features, lower elevations, and a significant geological history, providing valuable insights into the processes that have shaped the Earth's surface over time.

Q2: Explain the significance of residual mountains in understanding the Earth's geological history and resource distribution.

Answer: Residual mountains play a significant role in understanding the Earth's geological history as they represent remnants of ancient landforms that have undergone prolonged erosion. By studying these mountains, geologists can gain insights into past tectonic activity, climate change, and erosion processes. Residual mountains often contain valuable mineral deposits due to the concentration of resistant rocks and prolonged exposure to natural elements. For instance, the Aravalli Range in India has been known for its rich deposits of minerals, including lead, zinc, and copper, making it economically significant.

Q3: Compare and contrast the formation of residual mountains with that of fold and block mountains.

Answer: Residual mountains are formed primarily through the process of erosion, which wears away the softer layers of rock, leaving behind more resistant formations. In contrast, fold mountains are created by the folding of the Earth's crust due to tectonic forces, leading to high peaks and rugged terrains. Examples include the Himalayas. Block mountains form when large areas of the Earth's crust are faulted and uplifted or tilted, creating steep slopes and flat-topped blocks, as seen in the Sierra Nevada. While residual mountains are characterized by rounded, eroded features, fold and block mountains are marked by more dramatic relief and recent tectonic activity.

Previous Year Questions on Residual Mountains

1. UPSC CSE Prelims 2018:

Question: Which of the following mountains is considered a residual mountain?

A) Andes
B) Ural Mountains
C) Himalayas
D) Alps

Answer: (B)

Explanation: The Ural Mountains are considered residual mountains, formed through extensive erosion of ancient geological formations.

2. UPSC CSE Mains 2017 (GS Paper 1):

Question: "Examine the role of residual mountains in shaping regional landscapes and their economic significance."

Answer: Residual mountains significantly influence regional landscapes by providing elevated landforms that contrast with surrounding plains. They often host unique ecosystems and serve as reservoirs for valuable minerals due to their ancient geological origins. The economic significance of residual mountains lies in their mineral wealth, with examples like the Aravalli Range in India known for deposits of lead, zinc, and marble. The study of these mountains also provides insights into geological processes that shaped the Earth's crust, contributing to a better understanding of natural history and resource management.