Day 62 | RAS Mains 2025 Answer Writing | 90 Days

90 Days RAS Mains 2025 Answer Writing

This is Day 62 | 90 Days RAS Mains 2025 Answer Writing, We will cover the whole RAS Mains 2025 with this 90-day answer writing program

Click here for the complete 90 days schedule (English Medium)

Click here for complete 90 days schedule (Hindi Medium)

GS Answer Writing – Structure of the Earth and Geological Time Scale | Broad Physical Features: Mountains, Plateaus, Plains, Deserts । Elaboration

The Pamirs are a highland region in Central Asia. The Pamir Knot is a nodal orogenic uplift at the center of the Pamir mountain area. The Pamir Knot is a the convergence of several major Eurasian mountain ranges, including the Hindu Kush, the Karakoram Range, the Kunlun Mountains, and the Tien Shan 

Extension: Kyrgyzstan, Kazakhstan, Tajikistan, Turkmenistan and parts of China.

  1. Karst plain:   Any limestone or dolomitic region showing typical landforms produced by the action of groundwater through the processes of solution and deposition is called Karst topography. 
  • This was named after the typical topography developed in limestone rocks in the Karst region in the Balkans. The Karst plains of Nainital and Almora in India ,Yugoslavia and France are its other examples.
  • The karst topography is also characterised by erosional and depositional landforms. 
  1. Erosional landforms → Pools, Sinkholes, Lapies and. Limestone Pavements.
  2. Depositional landforms include stalactites, stalagmites, and Pillars.

  1. Loess plain – These plains are formed in desert areas, due to the deposition of sand particles by the wind. 
  • Loess plains found in China, Argentina and near Caspian Sea are its remarkable examples. 
  1. Piedmont plateau-
  • These plateaus are formed on the foothills of the mountains, having mountain on one side and sea or plain on the other. these are also called the plateaus of denudation
  • Petagonian plateau of Argentina is situated at the foothills of Andes mountain and facing the Atlantic ocean 
  • The plateau of Malwa in India, the Appallachian situated between the Appalachian Mountain and the Atlantic Coastal Plain in U.S.A


The Geological Time Scale (GTS) is a system of chronological dating that describes the timing and relationships of events that have occurred during Earth’s history.Through its hierarchical structure, the GTS subdivides Earth’s history into eons, eras, periods, epochs, and ages, each representing distinct intervals of time characterized by specific geological and biological phenomena. 

EonsEraPeriodEpochAge/Years before PresentLife/Major events
Phanerozoic Eon
Cenozoic 65 mn years to presentLatest era2 periodAge of mammals
Quaternary(2 mn year ago to present)Holocene0-10,000 Age of Human Evolution : Modern Man
Agriculture and Domestication of animal
ongoing biodiversity loss, anthropocene impact
Pleistocene10,000-2 mnmammals  evolution → monkeys and homosapiens
development of modern human behaviors
Tertiary(2-65 mn years ago)Pliocene2-5 mnemergence of early human ancestors
Miocene 5-24 mnFirst Homininae (humans and their ancestors, and chimps and gorillas).
Warmer global temperature, expansion of grasslands and forests 
Oligocene24-37 mnEmergence of grasslands → elephants, cats etc
Forefather of man : Anthropoid Apes
Eocene37-58 mnfirst grasses; rabbits and hare
spread of angiosperms (flowering plants) 
Paleocene57-65 mnadaptive radiation of mammals
Small mammals : rat – mice
Mesozoic65- 245 mn year ago3 periodsCretaceous65-144 mninsects, modern mammals, and bird groups, first flowering plant
K-T extinction → Extinction of Dinosaurs  
Jurassic144-208 mnAge of Dinosaurs
First bird, first true crocodile, first true mammal evolved
Triassic208-245 mnFrogs and turtles appeared
 First dinosaurs
4th mass extinction 
Paleozoic 245-570 mn6 periodsEnded with largest mass extinctionPermian245-286 mnReptile dominate, replace amphibians 
Carboniferous286-360 mnAmphibians diversify, first reptiles; vertebrates Coal Beds → coal forming forests 
Devonian 360-408 mnAge of fishes, first amphibiansPrimitive forests
Silurian408-438 mnEvolution of fish ⇒ Appearance of jawed fishes, coral reefs
First trace of life on land : early vascular plants
Ordovician 438-505 mnDiversification of marine life → First Fish, Trilobites
Camberian505-570 mnCambrian explosion First marine invertebrates
Still no terrestrial life
ProterozoicPrecamberian (Eozoic)570-2500 mnEvolution of abundant soft bodied multicellular organism (arthropods)
Archeon2500-3000 mnLife began in ocean : anaerobic bacteria
 By the end → Blue green algae and unicellular bacteria 
Hadean 3000-5000 mnStabilization of core and crust 
development of atmosphere and ocean (Rich in CO2 )
Origin of starsSupernovaBigbang5000- 13700 mn5000 mn12000 mn13700 mnOrigin of the sun
Origin of Universe

Paper 4 (Comprehension part) –  Elaboration

Child is the father of man

Childhood is one of the most important aspects of our life. Right from learning our first words to learning languages and reading and writing, each and everything that is thought in our childhood will shape our career and our persona. As and when we grow older, some of the things might be forgotten but will always be stored in our subconscious. It is usually referred to as nostalgia. Kids would have dreamt of becoming an actor or a cricketer or a pilot when they were of small age but as they grow up and face the realities of life, most of them end up working for a company in a 9 to 5 monotonous job.

The kinds of people we surround ourselves with defines who we are. As our elders used to say, a thief will always surround himself with other thieves, a good student will always surround himself or herself with other good students. I think it’s the basic nature of human life that like-minded people synchronise easily with each other.

Day 62 | 90 Days RAS Mains 2025 Answer Writing

Day 62 | 90 Days RAS Mains 2025 Answer Writing

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