Contents

Physical State of the Earth                         


  • There are three main layers of the earth. 1) Core        2) Mantle        3) Crust   
  • Core:
  • Core is a ball like structure which is present in the centre of the earth. It is divided in to two parts.
  • a) Inner core
  • b) Outer core
  • Inner core: Inner core is hard and solid.
  • It is 1250km thick and nearly 43000C hot.
  • Outer core: The outer core is in semi liquid form.
  • It is 2250km thick and about 37000C hot.
  • Mantle:
  • It is the second layer of the earth.
  • It is about 3000km thick.
  • Mantle layer is composed of Iron, Silicon and Magnesium elements.
  • Temperature of the upper portion of the mantle is 8700C that reaches up to 36000C in the lower portion.
  • Crust:
  • It is the lightest and thinnest layer of the earth.
  • It is mostly composed of Silicon and Aluminum element.
  • 20 to 70 km average thickness at continents, while 5 to 10km at ocean.
  • Faults: The crust of the earth is broken in different places. The broken lines are called faults.
  • There are three types of Faults. 1) Normal Fault  2) Reverse Fault       3) Lateral Fault         
  • Important faults of Pakistan:
  • Main Karakorum Fault: It is located in Northern areas of Pakistan, Kashmir and Gilgit Bultistan.
  • Jhelum Fault: It’s run through Jhelum District and Rawalpindi.                    
  • Kalabagh Fault: It passes through Kalabagh town, District Mianwali and Jhelum.
  • Chaman Fault: It is found in Baluchistan and goes through Chaman.
  • Salt Range thrust: It passes through Chakwal, Jhelum and many other areas.           
  • In December 2004, an earthquake came in the Western coast of Sumatra (Indonesia). Its intensity on Richter scale was 9.2 on reaching the coast the waves got a height of more than 30 meter, nearly 230,000 people died.
  • The coastal areas of Pacific Ocean (بحرالکائل ) are called “Ring of Fire” (آگ کا گولہ).
  • Mount Saint Hallen, after 120 years of dormancy ejected lava on 20th March, 1980. It caused a huge economic and human loss.


MCQs                                                                       


There are …………..main layers of Earth.
a) 2     

b) 3                 

c) 4     

d) 5


The property of the big three layers of the earth resemble the………
a) Onion                     

b) Ball             
c)  Tomato                  

d) Egg


Which of the following is resembles the yolk of an egg?
a) Core                                   

b) Crust
c) Mantle                    

d) none of these



Core is divides in how many parts?
a) 2     

b) 3                 

c) 4     

d) 5