UPSC

Crust - Thinnest & Lightest Layer

Crust is differentiated into Continental Crust and Oceanic Crust

Origin and evolution of the earth's crust

• First crust - the first crust was formed was probably because of cooling off the planet from the ancient nebula.
• Meteorite impacts - In the absence of atmosphere, the earth surface must have been overwhelmed by meteorite impacts that must have cracked the earth's crust at numerous places resulting in pressure release of the mantle, mantle turbulence, first convection cells and numerous volcanic eruptions on the surface.
• Mafic eruptions - The eruptions must have been extremely mafic even after partial melting of the mantle rocks.
• First oceanic crust / Basalt - These mafic eruptions must have subducted many times and recycled before the first oceanic crust. Basalt was formed.
• First microcontinent - The subduction of these 1st ocean basalts must have created the first continental andesite. These were the first microcontinents and once formed can float and move on the surface but resist subduction.
• Protocontinent - the microcontinents must have collided with one another fused forming a larger continent and first fold mountains must have been formed the protocontinent.

Peninsular India has numerous such micro continent which has been fused. 
The three major micro or proto continents are are 
 1. Singhbum proto continent
 2. Dharwad proto continent
 3. Aravali proto continent
These proto continents fused along Narmada-Son-Godavari river lineaments.

• Ancient fold mountains - every time the continents collide there must have formed ancient fold mountains.

The Aravalis are the remnants of such ancient fold mountains. 

• Earth is Unique - This process of tectonic dynamism is found on no other planet and may to some extent in Venus. Hence no other planet as the type of crust earth has and the fold mountains our earth has.

The processes in the origin and evolution of earth is not the same as the theories and processes in the origin of a earth crust. 

1. Linkages between development and spread of extremism.
2. Role of external state and non-state actors in creating challenges to internal security.
3. Challenges to internal security through communication networks, the role of media and social networking sites in internal security challenges, basics of cybersecurity; money-laundering, and its prevention.
4. Security challenges and their management in border areas - linkages of organized crime with terrorism.
5. Various Security forces and agencies and their mandate.

Structural features.

• coastal plains are depositional plains along the peninsular coast
• They are younger and will have alluvium
• Predominantly river in aluvium and less marine alluvium

Genesis.

• eastern and western coastal plains are mostly composite plains.
• composite planes have features of submergent emergent and features of neutral coastline.
• Malabar - emergent smoother lagoons. Vembanad lagoon, ashtamudi lagoon Kollam
• Canara Karnataka - submergent coast
• Konkan - submergent and emergent
• Kathiyawar - submergent and emergent
• Coromandel - emergent lagoon pulicat lagoon
• Andhra - submergent
• Odisha - emergent chilika lake shot Island wheeler Island kalam Island
• Bengal coast - evidences of river rejuvenation

Coastal Plains

• Depositional plains along the peninsular coast
• Younger and have alluvium (Riverine alluvium - (predominant) and Marine alluvium)

3 types - Degree of compactness

1. Compact / Clustered
2. Dispersed
3. Semi - Clustered

Patterns

1. Rectangular
2. Circular
3. Amorphous

Rectangular

• Hollow
• Grid
• Ribbon / Strip

Circular

Reasons - compact

• Wet Point
• Security

Variants

• Annual
• Radial

Horse Shoe

• Mallital
• Tallital

Amorphous

No two cities are similar but invariably they have some commonalities on which they may be grouped into categories. The earliest classification was based on the evolutionary stages of a city.

Aurosseau gave the first functional classification of cities. He classified the cities on the basis of dominant functions.

Aurosseau's functional classification of cities

1. Administrative towns
   • Cities that perform an administrative function
   • Washington DC, Gandhinagar, Delhi, Islamabad, Brasilia
2. Cultural cities
   • They are cultural centers
   • Varanasi Saint Petersburg Madurai Venice
3. Recreational center
   • Like hill stations
   • Shimla, Las-Vegas
   • Beach town Goa
4. Manufacturing center
   • Bokaro, Detroit, Pittsburgh, Birmingham, etc.
5. Defense towns
   • Made for security reasons
   • Cantonment areas like Jabalpur, Ranikhet, Rawalpindi, Edinburgh, etc.
6. Centers for communication
   • Mumbai, Singapore, Rotterdam, Colombo, Mugalsarai, Itarsi, Khadakpur

Aurosseau's scheme was based on subjective evaluation in depicting the nature of a city. It did not use any statistical method.

Modifications over this scheme started using statistical data such as the proportion of population employed in certain categories of function. In India, one such example of quantitative statistics-based classification was that of Ashok Mitra.

Ashok Mitra's classification of Indian cities

• He used census data to classify the Indian cities
• The 1971 census identified 9 categories of workers
  1. Cultivators
  2. Agricultural labor other than cultivators
  3. Workers in forestry fishing and mining
  4. workers in housing
  5. Manufacturing
  6. Construction other than housing
  7. Trade and commerce
  8. Transport communication
  9. Other services

Ashok Mitra didn't consider function 1 and 2 because they are purely agriculture function.

Manufacturing functions - Functions 3, 4, 5, and 6 were together considered as Manufacturing functions.

Forestry fisheries and mining are primary activity but mining is related to industry and so also many forestry activities.

Trade functions - Functions 7 and 8 were considered as Trade functions.

Service function - Function 9 was considered as Service function.

For every city that he studied, statistically, he tried to establish the proportion of workers in each of the above three categories.

He tries to plot the city on a triangular graph on the basis of the proportion of workers in each category of employment. Namely Services, trade, and manufacturing.

For identifying the character of the city, Ashok Mitra first draws an incircle and subdivides the incircle into three concentric zones of equal width because the graph is divided in 4 parts.

• Zone 1 - Depict city with maximum diversification
• Zone 2 - They are cities with moderate diversification
• Zone 3 - Cities with function predominantly accentuated
• Zone 4 - City with function highly accentuated

Zone 3 and Zone 4 depicts cities with specialization where some category of function is the character of the city.

With the diversity of soil forming factors and processes there are innumerable types of soils on earth. Soil classification is a technique in grouping soil based on some proper parameters so as to study soils more objectively.

Doku chiev.

He was a Russian pedologist. His was the first attempt in soil classification.

There are two ways of classification.

1. on the basis of genesis - primary condition is climate
2. On the basis of soil property / morphological classification

Genetic classification based on climate is more appropriate in geographical perspective because it can detail pattern of soil distribution and relate it to the climate types across the world.

If not specified in the question, the genetic scheme needs to be detailed while morphological is mentioned.

Morphological classification is more detail and more relevant in agriculture planning. It is difficult to make a world map on the basis of rock property.

Marbut scheme.

Doku Chiev gave the first scheme and was modified by Glinka. Both of them where Russians.

Marbut modified Glinkas scheme for America. Eventually he expanded it for the world soil types.

Marbut classified the soils on the basis of soil forming factors.

broadly there are three types of soils

• zonal
• intrazonal
• azonal

zonal

Podsols.

• pedalfer soil of cool humid region
• Represented in taiga
• The process is podsolization.
• Formed due to leaching in the presence of chelating agents
• Aluminium and iron oxides are more mobile and form sesquioxides. They become thick hard iron pans.
• Acidic greyish in colour.
• Not the best for agriculture
• Lumbering is the main activity

Latosols.

• variants of laterites
• Leaching and laterization process
• Condition required is humid and warm
• Good formation of laterites. Alternate wet and dry conditions - uplands monsoonal
• Silicon is more mobile and hence leached.
• B illuviated layer is silicon enriched
• Soil is red in colour because of iron and aluminium oxides.
• Aluminium is acidic in nature.

chernozems

seirozems

Morphological classification of soil.

• USDA
• On the basis soil properties
• Properties nutrients texture soil profile soil horizons PH value colour
• This is a very detailed scheme
• It has application in agriculture planning

This classification is not the best scheme in understanding the spatial pattern of soil distribution.

1. Enti
2. Insepti
3. Histo
4. Aridi
5. Molli
6. Verti
7. Alfi
8. Lato ??

Humanistic Geography

The most extreme backlash against quantification is humanistic backlash. It was against positivism and against any form of quantification. It also rejected the objective analysis in establishing the cause-effect relationship of a phenomenon or its pattern. It believes that the reasons for any man-environmental relationship have its root in the man himself which cannot be known objectively. Please there is nothing called as objective reality or real environment and what exists are subjective perceptions that are dynamic and can never be deciphered with certainty and precision. it is there for against mental maps and the techniques it suggests are more awake and difficult to replicate with objectivity. Techniques like b e r s t h a n getting into the minds of individuals and hermeneutics technique of continuous cyclic debates in interpretations and re interpretation of an event and phenomenon.

humanistic geography developed under different schools. with the purpose of studying and appreciating all aspects of man and management relationship it was important to understand the basis in the relationship without trying to generalize the cores into a law or a model when the reasons were shot in the ideas it is called idealism. The reality acid exists is constituted in one's mind first. Angiography idealism was part in by Harish and goyal CA.

for Ralph and coke the routes in a man and environment relationship is the environment are the phenomenon the subject cognitive eggs experience with which he develops the idea the phenomenon becomes the essence that distills into an idea this was the school of phenomenology.

School of Existentialism

Before the essence of a phenomenon, there exists a man first who experiences a phenomenon that becomes the basis of an idea.

For example, for every landscape that has to be someone who can be held accountable, this is a school of existentialism in geography.

Identity - Critique of positivism

Humanistic geography and its methods, techniques, and philosophy remained a very vague school of thought. Its identity was largely a critique of positivism and never developed into an independent geographical paradigm.

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