EARTH SCIENCE QUESTIONS :what seperates the crust from the mantle?

Question

1.what part of the mantle makes up the asthenosphere
2.what is is made of?
3.how is the contenental crust different from oceanic crust ?

Answer 1

look at the outer mantle and the crust together. Here we make a difference in asthenosphere and lithosphere.
Asthenosphere: The tough liquid part of the outer mantle.
Lithosphere: The stiffer part of the outer mantle and the crust. The lithosphere 'floats' on the asthenosphere, like ice on water.

The oceanic crust of the Earth is different from its continental crust. The oceanic crust is 5 km (3 mi) to 10 km (6 mi) thickand is composed primarily of basalt, diabase, and gabbro. The continental crust is typically from 30 km (20 mi) to 50 km (30 mi) thick, and it is mostly composed of less dense rocks than is the oceanic crust. Some of these less dense rocks, such as granite, are common in the continental crust but rare to absent in the oceanic crust
The crust of the Earth is composed of a great variety of igneous, metamorphic, and sedimentary rocks.

Answer 2

1) The upper most part of the mantle make the asthenosphere, which is by definition hot, partially molten layer of Earth, lying below the lithosphere (the rocky outer layer of Earth) which means it is above the mantle.
The asthenosphere extends from approximately 100 to 350 km (60 to 220 mi) below Earth’s surface. In some areas it extends to a depth of 700 km (435 mi).
This may be considered as a "transition zone" from solid crust (lithosphere) to molten mantle.

2)It is made of denser but plastic (semi-molten, wax-like, capable of having elastic properties) rocks compared to the lighter but solid rocks of lithosphere. Why? Because temperature and pressure increase with depth. Esthenosphere is 100 to 350 km down with tonnes and tonnes of weight per square inch on the top.

3) By definition, the part of the outer shell of Earth that constitutes the continents and the rocks beneath them down to the level of the mantle is called Continental Crust.
In most areas it is composed of sedimentary rocks near the surface and metamorphic rocks at a lower depth.
To me the Oceanic Crust is nothing but the extension of Continental crust having a huge depression, like a mountain rising to higher altitude on the other side of the "Continental Crust".

At some places the thickness of crust in the ocean become dangerously thin giving way to lava of the volcanos at the sea floor.
This is the only significant difference, otherwise crust is crust, and there is no way to divide it into continental or oceanic crust.

Answer 3

Asthenosphere is a semi solid molten metal. Visit my site to see inner parts of earth layers. I am doing research work in early warning systems.I am the one issued the warning 2 hours before Tsunami struck our Indian coast.My warning was ignored.
Earth structure.
http://www.groovle.com/custom/homepage/dbedd28145072d4111c7e335280f6f3e/

Answer 4

The Mohorovicic discontinuity
1.upper mantle
2.60% olivine rest pyroxenes, spienel and garnet
3.oceanic crust is basaltic and heavy as compared to continental crust.the main constituents of oceanic crust are SiAl