NCERT Class 11 Geography Chapter 2: The Origin and Evolution of the Earth YouTube Lecture Handouts

Get unlimited access to the best preparation resource for UGC : Get detailed illustrated notes covering entire syllabus: point-by-point for high retention.

Download PDF of This Page (Size: 222K) ↧

Get video tutorial on: Examrace YouTube Channel

Origin of Earth – Early Theories

• Nebular Hypothesis - Kant & revised by Laplace

• Chamberlain & Moulton – Cigar Shaped star - Planetesimal Theory

• Jeans & Jefferys – Tidal Theory

• Otto Schimdt – Dust Cloud (revised nebular hypothesis)

• Watch Video Lecture on YouTube: Watch on YouTube: Early Theories of Origin of Earth

  Early Theories of Origin of Earth

  Loading Video •••

  Watch this video on YouTube

Origin of Earth – Modern Theories

• Big Bang Theory – Expanding universe hypothesis (Hubble in 1920 proved expanding universe)

• Hoyle – Steady state

• Watch Video Lecture on YouTube: Watch on YouTube: Modern Theories of Origin of Earth

  Modern Theories of Origin of Earth

  Loading Video •••

  Watch this video on YouTube

Star Formation

• Density difference lead to diff. in gravitational force

• Galaxy – many stars – spread over many light years

• Diameter of galaxy: 80,000 to 1,50,000 light years (distance)

Planet Formation

• Star localized in nebula – core & disc formed

• Gas cloud condense around core – by cohesion – planetesimals

• Planetesimal accrete to form planets

Solar System

• Nebula collapsed 5-5.6 billion years ago

• Planets formed 4.6 billion years ago

• Inner or Terrestrial Planets (till Mars) – too warm for gas to condense, solar winds were intense, small & low gravity couldn’t hold gas

• Outer or Jovian or Gas Giant Planets: H & He

• Watch Video Lecture on YouTube: Watch on YouTube: Solar System

  Solar System

  Loading Video •••

  Watch this video on YouTube

Moon

• Natural Satellite of earth

• Darwin – earth & moon originated from single body – dumb-bell shaped body that broke

Evolution of Earth

Origin of Life

-Manishika