This blog is soley for educational purposes, made only for the ACE Geography girls of PLMGSS. Thank you for your kind cooperation.

Saturday, February 26, 2011

Earth's Layers


What are these Layer of the Earth made of?
  The outermost layer of the Earth is the crust. It is solid and comprises the continents and ocean basins. The crust has a variable thickness, being 35-70 km thick in the continents and 5-10 km thick in the ocean basins. The crust is composed mainly of alumino - silicates. 
  The mantle is liquid and composed mainly of ferro-magnesium silicates.This is where most of the internal heat of the Earth is located. Large convective cells in the mantle circulate heat and may drive plate tectonic processes.
  The outer core is liquid and is composed mainly of a nickel-iron alloy. While the solid inner core is almost entirely composed of iron. Earth's magnetic field is believed to be controlled by the liquid outer core. The outer core is 2300 km thick and the inner core is 1200 km thick.

Why is the Core Solid???
Inner core is thought to play an important role in the generation of Earth's magnetic fields by dynamo action in the liquid outer core.The existence of the inner core also changes the dynamic motions of liquid in the outer core as it grows and may help fix the magnetic field since it is expected to be a great deal more resistant to flow than the outer core liquid.

How does the Mantle Affect Us?
  Because the earth is very hot inside, a current of heat flows from the core to the crust. This is called convection current and it also takes place in the mantle. This current cools down as it comes closer to the surface of the earth. As a result, the rising of the current decreases and goes into horizontal direction along the bottom of the crust. When the current cools down more, the convection current descends again and goes to the inner earth. There the temperature increases and the current rises again. This goes on and on.
  When the current comes at a weaker part of the crust, for example at a volcano, magma comes above the earth's surface. The convection current along the bottom of the crust causes the moving of the tectonic plates. This is called plate tectonics. The movement of these plates goes very slowly. The bumping of two tectonic plates causes an earthquake.

  As I was doing my research, these three words, Asthenosphere, Mesosphere and Lithosphere came out very often so i decided to write the definition about it.
  The asthenosphere is a zone of the earth's mantle that lies beneath the lithosphere and consists of several hundred kilometers of deformable rock. It is solid rock, but  soft and flows easily (ductile).
  The lithosphere is the outer part of the earth, consisting of the crust and upper mantle, approximately 100 km (62 mi.) thick.(up to 200 km thick beneath continents, thinner beneath oceanic ridges and rift valleys), very brittle, easily fractures at low temperature.The lithosphere is comprised of both crust and part of the upper mantle.
  The mesosphere is about 2500 km thick, solid rock, but still capable of flowing.


  Also, as I was researching, these questions came out and made me really curious. Would the Earth run out of magma? If so, then what would happen and how would it affect our lives? Another question. It may sound a little unrealistic but its worth posting. What would happen if i drilled a tunnel through the center of the earth and jump into it?

                                               End of Post ^-^ 

Friday, February 18, 2011

Geography Lesson on the 18.02.11

RECAP:
We learnt about the some of characteristics of the...
- Igneous rocks
- Sedimentary rocks
- Metamorphic rocks
We did the sedimentary rocks in more detail.

Sedimentary Rocks:
- Some examples of sedimentary rocks are conglomerate, limestone and shale.
- They have very obvious layers.
- They are broken down very easily, especially limestone.
- The sedimentary rock covers of the continents of the Earth's crust is extensive, but the total contribution of sedimentary rocks is estimated to be only 5% of the total volume of the crust, much less then the igneous rocks and the metamorphic rocks.
- Sedimentary rocks are deposited in layers as strata, forming a structure called bedding.

How are the Sedimentary Rocks formed?
The sediments are deposited and they pile up in layers, with the weight of more layers piling up, the sediments will cament together and harden, forming the sedimentary rock.

I find this website diificult to understand as it is very profound. They call it a 'A Basic Sedimentary Rock Classification' but i dont understand it. But still, its about sedimentary rocks:) You can visit it if you have the time: http://csmres.jmu.edu/geollab/fichter/SedRx/sedclass.html

Some pictures of Sedimentary rocks:):)




    

Saturday, February 12, 2011

11/02/11 lesson recap

What we have learnt this week:

1) Scales
Atlas -> Book of Maps -> Location -> Scales

  • There are both large scales and small scales.

2)  Land Mass
World (International)   
Region                             
Continents
Countries
Cities
Towns
Community/ Village

3) Oceans
  • Pacific Ocean ( America & Asia)
  • Atlantic Ocean ( Africa & South America)
  • Indian Ocean ( Below India)
  • Southern Ocean ( Above Antarctica)
  • Arctic Ocean (Above Europe)

4) Fragile Earth
 The interrelationship between physical Earth and the human environment

Human actions causes  -> Impact on environment -> Manage the impact

5) Physical Environment (Rocks)
  • Rocks are small scale
  • Landforms are large scale
How are they linked?
  • Rocks make up massive landforms.
What are rocks?
  • Rocks are solid materials on the Earth’s crust
  • Made up of minerals like Quartz and Sand

                                                   End of Recap^-^