Orders of Relief

The topographical features that appears on the surface of the earth are actually the products of endogenic and exogenous processes.

What is Relief?

Relief is known as the difference between two elevation points on the surface of the earth. If a surface is relatively flat then it is considered to be having low relief, while mountainous regions are said to be having high relief.

Classification or Orders of Relief

Relief can be classified as follows:

• First order relief
• Second order relief
• Third order relief

First order relief: Entire lithosphere which consists of continental crust as well as the oceanic crust comes under first order relief.

Continental crust have lower density than the oceanic crust and is made up of granitic rock consisting of Silica and Aluminium predominantly. While oceanic crust is made up of basaltic rocks and majorly consists of Silica and Magnesium.

First order relief basically reflects the original cooling and solidification of Earth's crust at the time of its formation. Continental shields and contracted Panthalassa (largest ocean known as Pacific) are considered to be included in first order relief.

Second order relief: This type of relief basically consists of all endogenic forces which originates from within earth's crust/surface. Endogenic forces are responsible for developing variations on the surface of the earth, hence they are also known as variability developers.

Endogenic processes are classified as follows:

• Diastrophism aka mountain building forces is responsible for the development of block as well as fold mountains.
• Volcanism/Earth quakes.

Mountains are the best example of product of endogenic processes on continental crust. While submarine ridges (formed due to solidification of magma) and trenches forms the best example in oceanic crust.

Third order relief: This type of relief basically consists of exogenic forces. Exogenic forces are those forces which originates on the surface of the earth.

All exogenic forces are also known as levellers because they are responsible for levelling (bringing variations) the surface of the earth. The levelling process includes erosion, transportation and deposition and as a result valleys (due to erosion) and deltas (due to deposition) are formed. Following are the agents which carry out the whole levelling process:

• Running water.
• Wind.
• Underground water.
• Glacier.
• Sea waves.

Important note: All the above mentioned levelling agents don't work after the shoreline. This means that third order relief is only confined to the continental crust.

However continental margin (consisting of continental rise, continental slope and continental shelf) may experience third order relief features because of change in mean sea level due to change in climatic conditions or region specific endogenic modifications.

Image credit: http://en.wikipedia.org/wiki/File:Continental_shelf.png

Physical Geography: Climatology Previous Year Questions

Following are the questions on Climatology (Paper-1, Physical Geography) that previously appeared in Civil Services Mains (Optional) Examination:

• Year 2014: What is the nature and origin of Indian monsoon? And what are the recent techniques for the prediction of it? AND Describe the origin and development of thunderstorms by giving suitable examples. AND What are the salient features of Sirocco and Mistral winds?
• Year 2013: What is DEW point? What are the various forms of condensation? AND What is the impact of local winds on the climate of an area? Give suitable examples. AND What are the difference between Storm Surges and Seiches?
• Year 2012: What is the impact of Cryosphere on the climate of the world? AND Classification of air masses and explain how cP airmass affects the global climate? AND Compare and contrast tropical cyclone and temperate cyclones.
• Year 2011: Global distribution of precipitation. AND Discuss "Contemporary global climate change is an anthropogenic phenomena".
• Year 2010: What do you mean by inversion of temperature? AND What do you mean by polar front? and how does a cyclone develop along this front? Also describe the conditions of whether associated with it. AND What are various kinds of atmospheric humidity and their associated forms?
• Year 2009: Discuss affect of climate change on urban areas.
• Year 2008: Explain the mechanism and origin of Monsoon winds. What is the role of El Nino on the circulation of the Monsoon?
• Year 2007: Discuss the development of local winds and their influence on local weather. Give 3 examples of popular local winds in the world.
• Year 2006: Compare tropical cyclone with temperate cyclone, with reference to their structure and associated weather conditions with them.
• Year 2005: What are the salient features of climate classification system evolved by Koppen. Discuss the anomalies associated with it.
• Year 2004: No question asked.
• Year 2003: What is the mechanism and significance of tri-cellular meridional circulation of the atmosphere?
• Year 2002: What was the criteria which Thornthwaite adopted in his classification of world climate in 1948.
• Year 2001: What are air masses and how they are classified?
• Year 2000: Distribution of precipitation in the world.
• Year 1999: Compare tropical and temperate cyclones.
• Year 1998: What is the nature and composition of Earth’s atmosphere?
• Year 1997: What do you mean by air masses and how do they originate? Classify air masses and state the characteristics of any one of them.
• Year 1996: Critically examine the drawbacks of Koppen's classification of climates. How Thornthwaite attempted to overcome the limitations of Koppen's classification.
• Year 1995: Explain and illustrate the life cycle of a temperate cyclone. What are the weather conditions associated with a temperate cyclone?
• Year 1994: Koppen's classification of climates along with its merits and limitations.
• Year 1993: No question asked.
• Year 1992: What is the origin, movements and characteristics of air masses? How air masses influence the climate of the world?
• Year 1991: What is the origin, distribution and characteristics of tropical cyclones?

Physical Geography: Geomorphology Previous Year Questions

Following are the questions on Geomorphology (Paper-1, Physical Geography) that previously appeared in Civil Services Mains (Optional) Examination:

• Year 2014: What do you mean by mass wasting and weathering? Explain their significance in Geomorphology. OR Define Plate Tectonics Theory. How does this theory helps in explaining the formation of Himalayas and Appalachian mountains? OR What do you mean by erosion surfaces? State all the factors that are responsible for the development of erosion surfaces. OR What do you mean by meander? Explain the basic characteristics of entrenched meander and ingrown meander.
• Year 2013: Explain in 250 words what do you mean by base level and what are its types? OR Write in 150 words about what are the differences between arid cycle and normal cycle of Davis?
• Year 2012: Write in 250 words about various programs which are initiated by International Council of Science (ICSU) on Earth System Studies. OR Explain the characteristics of standard epigene cycle of erosion in 250 words. OR Write about systems approach to land form analysis in 150 words. OR Write in 150 words about Palaeozoic glacial evidence for Continental Drift. OR Explain in 400 words how Bosche and Haldenhang lead to the theory of slope replacement?
• Year 2011: What are the climatically controlled agents of erosion? Explain how they differ in their properties of matter and compare the land forms produced by each one of them. OR What do you mean by Isostasy as postulated by Airy and Pratt?
• Year 2010: Write short notes on Karst Topography. OR How seismic study helps us in determining the internal structure of earth? OR Explain why weathering is a complex phenomenon involving a number of processes and what are the factors that influences it?
• Year 2009: Write about geomorphic features that are found under Second Cycle of Erosion. AND L.C. King's view on slope development.
• Year 2008: What do you mean by Geomorphic cycle? What are the views of Davis and Penck on this cycle.
• Year 2007: What do you mean by Isostasy as postulated by Airy and Pratt?
• Year 2006: Describe Alfred Wegener's Continental Drift theory.
• Year 2005: "Structure is a dominant control factor in the evolution of landforms" - Discuss this statement citing suitable examples.
• Year 2004: Endogenic forces produces what type of landforms?
• Year 2003: Explain sequential development of landforms in coastal areas.
• Year 2002: Provide a Critique to Davis's model of Geographical Cycle.
• Year 2001: Critically analyse the theory of Isostasy.
• Year 2000: Write about the origin and growth of young fold mountains with reference to theory of Plate Tectonics.
• Year 1999: Difference between the theories of Continental Drift and Plate Tectonics.
• Year 1998: What do you mean by Volcanicity? Explain how Plate Tectonics theory helps in explaining the mechanism of volcanism and volcanic eruptions?
• Year 1997: What do you mean by polycyclic landforms? Analytically write about this type of land form of a selected region.
• Year 1996: What do you mean by mechanical and chemical weathering? How they are related in the formation of soil.
• Year 1995: What are the limitations of Continental Drift Theory? How Plate Tectonics Theory is an improvement over it?
• Year 1994: What is cycle of erosion? What are the differences in views of Penck and Davis on this cycle?
• Year 1993: What are the factors which are responsible for the rejuvenation in landscape? Also describe the resultant land form.
• Year 1992: How volcanism and diastrophism are responsible for evolution of landscape? Give suitable examples.