By Yauder Matheu Carillo Queniahan The interior of the earth
The Interior of the Earth - Structure of the Earth - Crust, mantle, core - Explaining Some Earth Phenomena - Earth’s magnetism (Gilbert’s experiment, the permanent magnet theory, the negative experiment, the dynamo theory, Fossil magnets) - convection and plate tectonics THE INTERIOR OF THE EARH
The interior structure of the Earth is layered in spherical shells like an onion, and has four major zones or layers.
Crust • The crust ranges from 5 to 70 km in depth and is the thinnest and outermost layer of the earth. • It has two kind of crusts: • Continental Crust • Oceanic Crust
Continental Crust • is the layer of granitic, sedimentary and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. • Consisting mostly of granitic rock, continental crust has a density of about 2.7 g/cm3 and is less dense than the material of the Earth's mantle.
Oceanic Crust • is the part of Earth's lithosphere that is under the ocean basins which is composed of mafic rocks, which is rich in iron and magnesium. • It is thinner than the continental crust, generally less than 10 kilometers thick, however it is more dense, having a mean density of about 3.3 g/cm3.
Mantle • is the layer between the crust and the outer core. • It’s a rocky shell composed of silicate rocks that are rich in iron and magnesium relative to the overlying crust, and is about 2,900 km thick that constitutes about 84% of Earth's volume.
Layers of the Mantle • Lithosphere -The thin outermost shell of the upper mantle is similar to the crust, though cooler and more rigid. Together with the crust, this layer is called the Earth’s lithosphere. • Asthenosphere - the ductile part of the earth just below the lithosphere, including the upper mantle. The asthenosphere is about 180 km thick.
Upper Mantle -It’s stronger and more solid than the asthenosphere.Below the crust down to a depth of about 670 kilometers is part of the upper mantle. • Lower Mantle -The rest of the mantle between the upper mantle and the core is known as the lower mantle. It is denser and hotter than the upper mantle.
Mohorovicic Discontinuity -Named after the pioneering Croatian seismologist AndrijaMohorovičić. It is the boundary between the Earth's crust and the mantle. • Gutenburg Discontinuity - Named after BenoGutenberg, it is the boundary between the Earth’s mantle and the core.
Outer Core • It is a liquid layer about 2,266 km thick composed of iron and nickel which lies above the Earth's solid inner core and below its mantle. • Because of its temperature which is about 4000 to 9000 degrees F, the metals in it are all in the liquid state.
Inner Core • its innermost part, is primarily a solid ball with a radius of about 1,220 km according to seismological studies. • the temperatures and pressures are so great that the metals are squeezed together and are not able to move about like a liquid, but are forced to vibrate in place as a solid. • The temperatures may reach 9000 degrees F. and the pressures are 45,000,000 pounds per square inch. This is 3,000,000 times the air pressure on you at sea level.
References • http://volcano.oregonstate.edu/education/vwlessons/lessons/Earths_layers/Earths_layers9.html • http://education.nationalgeographic.com/education/encyclopedia/mantle/?ar_a=1 • http://en.wikipedia.org/wiki/Structure_of_the_Earth
is the magnetic field that extends from the Earth’s interior to where it meets the solar wind, a stream of charged particles emanating from the Sun EARTH’S MAGNETISM
WILLIAM GILBERT William Gilbert (1544-1603) was an English scientist and physician who is credited by many as the “father of electricity and magnetism”.
The Terrella • Gilbert carried out many experiments, but the most famous one was his explanation, why the compass pointed north. He shaped a big lodestone into a sphere. Since it was meant be a model of the Earth, he named it "Terrella," meaning, "little Earth.“ • Over the surface of the Terrella he moved a magnetic compass. More accurately--since the compass had to stay horizontal--he moved the Terrella, placing the compass next to various points on it. • When the compass was level with the surface of the terrella, the needle always pointed to the magnetic north pole of the terrella.
The picture here shows what happened when the compass was perpendicular to the terrella; the poles are on the left and right, the equator on top, and the needle in general slants down, just the way Robert Norman observed. At the poles, it points straight down,on the equator it is horizontal. This experiment convinced him that the directionality of the compass was caused bythe Earth itself being a great magnet. Supposedly, he demonstrated his terrella to Queen Elizabeth--at least, a painting of such a demonstration exists.
PERMANENT MAGNET THEORY • Magnet • is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, and attracts or repels other magnets.
Permanent Magnet • an object made from a material that is magnetized and creates its own persistent magnetic field
Often called the Michelson-Morley experiment, the phrase actually refers to a series of experiments carried out by Albert Michelson and Edward Morley
The issue at hand… • By the end of the 1800s, the dominant theory of how light worked was that it was a wave of electromagnetic energy, because of experiments such as Young’s double slit experiment. • Michelson and Morley came up with the idea that they should be able to measure the motion of the Earth through the ether. • The ether was typically believed to be unmoving and static. But the earth was moving quickly.
What did they do? • To test this hypothesis, Michelson and Morley designed a device that split a beam of light and bounced it off mirrors so that it moved in different directions and finally hit the same target. • If the two beams traveled at the same distance along different paths through the ether, they should move at different speeds and therefore when they hit the final target screen, those light beams would be slightly out of phase with each other, which would create a recognizable interference pattern.
The device therefore came to be known as the Michelson interferometer.
The Result…. • Disappointing, because they found no evidence of the relative motion they were looking for. • No matter which path the beam took, light seemed to be moving at the precisely the same speed.
A Dynamo is a device for producing electricity by rotating an electrical conductor across magnetic lines of force Walter Elsasser and Edward Bullard developed a hypothesis that presented the earth as an electromagnet rather than a permanent magnet. They attributed the earth’s magnetism to the electric current produced in the earth’s interior, which in turn is continually produced by the movement of the liquid outer core What is a Dynamoand how is it used to describe the origin of the magnetosphere?
-They argued that the inner and outer core move with different speeds; it is this difference in speed that is the source of magnetism. If electricity is to be produced continuously, there should be a continuous rotation of the conductor. In Earth, the energy is thought to come from convection currents set in motion by heat produced by radioactivity in the core Cont.
The dynamo theory involves a chain of complex processes taking place in the earth’s core: *the core of the earth must consist of a material that conducts electricity as well as metal does *the material must be in liquid form * the conducting liquid must flow in some way (this is the stirring processes process providing the energy needed to sustain the field) For the Earth to work like a dynamo…
Fossil Magnets • -paleomagnetism; history of the earth’s magnetism • - development of instruments for measuring magnetism in rocks together with the refinements made in the techniques for establishing rock ages greatly aided scientists in their study of fossil magnets
Note to self: always leave a pack of sky flakes and a can of red bull inside fridge for emergency purposes. • These are bits of magnetic materials [Fe] in rocks which have preserved the magnetism of the earth at the time the rocks were formed • Many rocks contain iron-bearing minerals which are naturally magnetic • Studies of rocks in one place which were formed at different geologic times reveal varying magnetic directions and strengths
Note to self: not sleeping is detrimental to one’s health; the internet does not help either • One interpretation states that the earth is fixed and it is the magnetic poles which are shifting in position • Another interpretation is that the magnetic poles are fixed and it is the whole earth that moves with respect to these poles • A third interpretation is that the magnetic poles are fixed but only the upper layers of the earth are shifting about
Note to self: the fruit orange came before the color and English word orange • Fossil rocks are also distinguished between the north and the south pole • There is strong evidence that the poles of earth’s field have reversed many times in the past • the dynamo theory presents one possible explanation; the direction of the magnetic field is influenced by the direction of the movement of molten iron in the core