Geography Quiz: Geomorphology and Bio – Geography | 23 June, 2021

Dharwar system is later than the Archean system but older than the other systems.  

• The Dharwar period of rock formation has been largely fixed from 2500 million years ago to 1800 million years ago. 
• Dharwar Rock System is special because it is the first metamorphic sedimentary rocks in India. 
• They are named Dharwar system because they were first studied in Dharwar region of Karnataka.  
• But they are also found in Aravallis, Tamil Nadu, Chota-nagpur plateau, Meghalaya, Delhi, and the Himalayas region. 

• The Dharwar rocks are rich in iron ore, manganese, lead, zinc, gold, silver etc. 

Source: NCERT – XI Fundamentals of Physical Geography 

Latosols are soils found under tropical rainforests which have a relatively high content of iron and aluminum oxides. They are typically classified as oxisols or ferralsols. 

Source: G C Leong 

Hardness — relative resistance being scratched; ten minerals are selected to measure the degree of hardness from 1-10. They are: 

1. talc; 
2. gypsum; 
3. calcite;
4. fluorite; 
5. apatite; 
6. feldspar;
7. quartz; 
8. topaz; 
9. corundum;
10. Diamond.

Source: NCERT – XI Fundamentals of Physical Geography 

A process is a force applied on earth materials affecting the same.

• An agent is a mobile medium (like running water, moving ice masses, wind, waves and currents etc.) which removes, transports and deposits earth materials.
• Running water, groundwater, glaciers, wind, waves and currents, etc., can be called geomorphic agents.

Source: NCERT – XI Fundamentals of Physical Geography

All processes that move, elevate or build up portions of the earth’s crust come under diastrophism. They include:

• orogenic processes involving mountain building through severe folding and affecting long and narrow belts of the earth’s crust;
• epeirogenic processes involving uplift or warping of large parts of the earth’s crust;
• earthquakes involving local relatively minor movements;
• plate tectonics involving horizontal movements of crustal plates.

Source: NCERT – XI Fundamentals of Physical Geography

The earth’s crust is dynamic. You are well aware that it has moved and moves vertically and horizontally. Of course, it moved a bit faster in the past than the rate at which it is moving now.

• 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 external forces are known as exogenic forces and the internal forces are known as endogenic forces.
• 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 phenomenon of wearing down of relief variations of the surface of the earth through erosion is known as gradation.

Source: NCERT – XI Fundamentals of Physical Geography

A group of weathering processes viz; solution, carbonation, hydration, oxidation and reduction act on the rocks to decompose, dissolve or reduce them to a fine clastic state through chemical reactions by oxygen, surface and/or soil water and other acids.

• Water and air (oxygen and carbon dioxide) along with heat must be present to speed up all chemical reactions.
• Over and above the carbon dioxide present in the air, decomposition of plants and animals increases the quantity of carbon dioxide underground.
• These chemical reactions on various minerals are very much similar to the chemical reactions in a laboratory.
• There are five major types of mechanical weathering: thermal expansion, frost weathering, exfoliation, abrasion, and salt crystal growth.

Source: NCERT – XI Fundamentals of Physical Geography

Chaparral is sclerophyllous vegetation that is tolerant of seasonal drought.

• It consists of small trees, woody grasses and oleose, xerophytic shrubs that form a nearly continuous cover of intertwined branches.
• Usually less than 10 per cent of the ground is bare, though the proportion may be higher at inhospitable sites.

• Where annual precipitation is in the range 250–500 mm, plants may be only 1–2 m high, while crowns may reach 3.5–4 m where precipitation is 500–750 mm.
• In California chaparral is common at elevations of 300–1500 m. It occupies 3.4 million ha (8.5 per cent) of the state, particularly in its southern part and at moderate elevations.
• The European synonym for chaparral, maquis (in Italian, macchia, plural macchie), is derived from the Corsican word for a species of sun rose (Cistus), which is often a striking component of the maquis community.

Source: G C Leong

Tropical thorn forests occur in the areas which receive rainfall less than 50 cm.

• These consist of a variety of grasses and shrubs. It includes semi-arid areas of south west Punjab, Haryana, Rajasthan, Gujarat, Madhya Pradesh and Uttar Pradesh.
• In these forests, plants remain leafless for most part of the year and give an expression of scrub vegetation.
• Important species found are babool, ber, and wild date palm, khair, neem, khejri, palas, etc. Tussocky grass grows upto a height of 2 m as the under growth.

Source: NCERT – XI Fundamentals of Physical Geography

An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3,000 metres (9,800 ft) and 6,000 metres (20,000 ft).  

Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth’s surface. 

Source: NCERT – XI Fundamentals of Physical Geography