Explain the formation of thousands of islands in Indonesian and Philippines archipelagos. [150 Words] [10 Marks] [2014] !! Islands UPSC !! Formation !! How islands are formed ? !! How many islands in Indonesia? !! Islands Indonesia map !! How Philippine archipelago was formed ?

 

Index-

1. Explanation of the question
2. The information needed to understand the convective current
3. Formation of the conversion and the divergent boundary.
4. And in the last connecting the question with the convergent boundary of oceanic oceanic convergence
5. Answer writing structure
6. Answer

 

UNDERSTANDING QUESTION-

When the word (terminology)  "explain" is used in any given question, it simply means that the answer is demanding "in-depth" information, drawing on the knowledge, to produce an answer.

The same is the demand in this question, where actually the basic information has been asked about the formation of archipelagos concerning the Indonesian -& Philippines.

  👉ALL PAGES- LINKS INDEX👀

EXPLANATION-

     Now, it is a typical "physical World geography question" where we need to explain the formation of a group of volcanic islands that are connected through oceanic-oceanic plate convergence.

As we know-

1. If you go through the Earth's internal structure formation, we come to know the two primary layers, one is the lithosphere and the second is the asthenosphere.
2. The depth of the lithosphere on average is 100 KM, which is a combination of both -
3. continental crust and 
4. oceanic crust along with the solid upper portion of mental.
5. In the next layer, we have the semi-molten layer known as "asthenosphere", in which the temperature starts from 900 °C, and goes to about 3800 °C (which means the temperature gradient is about 2900 degrees centigrade.

     

👉NCERT-GEOGRAPHY-CLASS-06-LINK-PAGE 👀

We also know -

       

1. Inside the Earth's internal structure 
2. There is a gradual increase in temperature, which draws the reference that 
3. The lower or the bottom layer of asthenosphere maintains a high temperature in comparison to the upper layer.
4. If we follow the energy principle, it flows from high temperature to low temperature 
5. That means, now, the energy will flow from the bottom of the asthenosphere to the upper surface with material, and that is how we have the formation of the rising limb of the convection current.

The moment material gets up -

1. To the upper portion, it creates a space at the bottom, and the surrounding, comparatively low temperature material, with higher density, gets subsided and fills up the space, and, 
2. That's how the combination of rising limb and falling limb leads to the formation of a convective cell.
3. If we know this, then we also know that on the rising limb we have the divergent boundary and 
4. On the falling limb, we have the convergence boundary.

So-

1. Basically, this question is about the converging boundary concerning Oceanic-Oceanic conversion 
2. which leads to the 02 output 
3. One is the formation of TRENCH, and, 
4. Second melting of "LITHOSPHERIC PLATE" through the subduction 
5. lead to the formation of "MAGMA" and 
6. Following a volcanic eruption 
7. This results in the formation of a volcanic group of islands, which are well connected, known as archipelagos.

Indonesian Islands Map

      

Philippines Islands Map 

And that's how we connect this question to this explanation.

👉 UPSC-GEOGRAPHY+EVS MAINS ANSWER WRITING👀

 

ANSWER STRUCTURE

1. Introduction
2. Convergent diagram
3. Explanation
4. Conclusion

 

ANSWER-

Earth's internal structure suggests that a gradual increase in temperature and density up to Centre resulted in the formation of convective cells in the asthenosphere, over which the rising limb led to the formation of the subduction and resulted in Oceanic-Oceanic plate convergence.

   

In oceanic-oceanic convergence, we have to 02 out products, one is the formation of the trench, and the second is volcanic archipelagos, which are well connected group of islands, formed out of volcanic eruptions.

In respect of the Philippines archipelagos, we have convergence of the Philippines and Pacific Ocean plate, whereas, in respect of Indonesian archipelagos, convergence of the Philippines plate and Sunda oceanic plate, and that is how we have formation of the Philippines and Indonesian archipelagos respectively.

Volcanoes are a "construction unit" of Earth's continental crust, which is evident from the fact that shortly, all four major islands of Japan will be connecting together to form a large landmass.

🙏🙏

👉Discuss the geophysical characteristics of the Circum-Pacific Zone.[150 Words] [10 Marks] [2020]