Geomorphic processes

Multiple choice questions

(i) Which one of the following processes is a gradational process?

(a) Deposition

(b) Diastrophism

(c) Volcanism

(d) Erosion

(ii) Which one of the following materials is affected by hydration process?

(a) Granite

(b) Clay

(c) Quartz

(d) Salts

(iii) Debris avalanche can be included in the category of:

(a) Landslides

(b) Slow flow mass movements

(c) Rapid flow mass movements

(d) Subsidence

2. Answer the following questions in about 30 words.

(i) It is weathering that is responsible for bio-diversity on the earth. How?

Weathering results in break down of rocks into smaller fragments. This leads to formation of regolith and soil along with erosion and mass movements. Biodiversity is a result of forests and vegetation which depend upon the degree of weathering. For erosion to become significant, weathering must happen. This means weathering results in mass wasting, erosion and reduction of relief and erosion leads to changes in landforms.

(iii) What are the various mobile and mighty exogenic geomorphic agents and what is the prime job they perform?

The various mobile and mighty exogenic geomorphic agents are – rivers, glaciers, wind, sea-waves etc. Through erosion and transportation, these agents create different types of landforms and the materials that are carried by them get deposited below seas and oceans, deep sea basin etc. to form a different kind of landmass.

On the other hand, the exogenic processes include temperature, rainfall, wind, snowfall, sea-waves, running water. They perform the following jobs – weathering, erosion, deposition, denudation etc.

(iv) Is weathering essential as a pre-requisite in the formation of soils? Why?

Yes, weathering is an essential pre-requisite in the formation of soils. Weathering is action of elements of weather and climate over earth materials. Within weathering, a number of processes are involved that act either individually or together that impacts the earth materials and convert them into fragmental state. Weathering involves the elements of weather and climate to act that result in mechanical disintegration and chemical decomposition of rocks.

3. Answer the following questions in about 30 words.

(i) “Our earth is a playfield for two opposing groups of geomorphic processes.” Discuss.

Two opposing forces always act on our earth’s surface. These are – exogenic and endogenic. The external forces are known as exogenic forces and the internal forces are known as endogenic forces. The differences in the internal forces operating from within the earth which built up the crust have been responsible for the variations in the outer surface of the crust. The earth’s surface is being continuously subjected to external forces induced basically by energy (sunlight). Of course, the internal forces are still active though with different intensities. That means, the earth’s surface is being continuously subjected to by external forces originating within the earth’s atmosphere and by internal forces from within the earth.

The actions of exogenic forces result in wearing down (degradation) of relief/elevations and filling up (aggradation) of basins / depressions, on the earth’s surface. The endogenic forces continuously elevate or build up parts of the earth’s surface and hence the exogenic processes fail to even out the relief variations of the surface of the earth. So, variations remain as long as the opposing actions of exogenic and endogenic forces continue. In general terms, the endogenic forces are mainly land building forces and the exogenic processes are mainly land wearing forces.