Ha ha bumipun ada 7 lapisan juga podo dg Kitab saya.
Paulus Anak Wedus.
The Layer of Earth [hor_green_bar1.jpg]
[The interior of the Earth - copyright Calvin J. Hamilton] What is the
use of locating seismic discontinuities? Locating these disturbances
enable scientists to map the inner regions of the Earth. This science,
known as tomography originates from the knowledge gained from
discontinuities.
Tomographists have found that this planet is divided into six regions:
the inner core, the outer core, the lower mantle, the upper mantle, the
transition region, and the crust (oceanic and continental).
Here is a brief synopsis of the depths of each layer (in kilometers):
1. 0- 40 Crust
2. 40- 400 Upper mantle
3. 400- 650 Transition region
4. 650-2700 Lower mantle
5. 2700-2890 D'' layer
6. 2890-5150 Outer core
7. 5150-6378 Inner core
[The Interior of the Earth - copyright Calvin J. Hamilton] The inner
core is a solid section of the Earth and is unattached to the mantle,
being suspended by the molten outer core. This solidified state is the
result of a very intense pressure-freezing process that occurs in most
liquids when temperature decreases or pressure increases. The outer
core of Earth is a scorching hot, electrically conductive liquid in
which convection takes place. This inner layer in mutual combination
with the rotational motion of the Earth creates a dynamo effect where a
force ield of electrical currents is generated. This field is also
known as Earth's magnetic field, which is responsible for the
functioning of mechanical and biological compasses. This field also
causes a subtle jerking motion in the Earth's daily rotation. In terms
of the physical aspects of the outer core, the layer is dense, but not
as dense as pure molten iron, evidencing the presence of multiple
impurities having a lighter chemical makeup. According to scientists,
about 10% of this layer is composed of sulfur and/or oxygen due to the
fact that these two elements are abundant in the cosmos and dissolve
readily in molten iron.
[Crustal Plate Boudaries]
1. The outer core is in the range of 200 to 300 kilometers (125 to
188 miles) thick and represents about 4% of the mantle-crust mass. This
layer is sometimes identified as part of the lower mantle due to its
geographical nature. However, studies on seismic discontinuities
suggest that this "D" layer might differ chemically rom the lower
mantle lying above it.
2. Looking at the lower mantle, its chemical omposition includes
silicon, magnesium, and oxygen. Most likely, it probably also contains
some iron, calcium, and aluminum. This layer is comprised of 72.9% of
the antle-crust mass, making the Earth abundant in the chemical
elements of silicon, magnesium and oxygen, the layer's primary
components.
[A View of Saudi Arabia - courtesy NASA] 3. 3. Higher up, we
encounter the upper mantle. Through excavations in volcanoes,
scientists have found that this part of the crust composes of 15.3% of
the total mantle-crust mass and is made of crystalline forms of Olivine
(Mg,Fe)2SiO4 and pyroxene (Mg,Fe)SiO3. The upper mantle makes up 10.3%
of the Earth's mass, extending a depth of 6-250 miles (10-400
kilometers). A relatively large portion when compared to the other
interior layers. This layer is not completely made of solid minerals
for scientists speculate that the asthenosphere could be partly liquid
molten.
4. D: The D" layer of Earth is about 3% of Earth's mass, is 125 to
188 miles (200 to 300 kilometers) thick and covers about 4% of the
mantle-crust mass. This layer, in terms of whether it is part of the
lower mantle or an independent layer is still somewhat unclear. Based
on evidence collected from seismic discontinuities, the D" layer might
differ in chemical composition from the lower mantle above it.
5. The next layer, the Transition region comprises 7.5% of Earth's
mass with a depth of 250-406 miles (400-650 kilometers). This layer is
also known as the mesosphere and is 11.1% of the mantle-crust. It is
made of mainly basaltic magmas with amounts of calcium, aluminum and
garnet (an aluminum-bearing silicate mineral). The layer becomes dense
when the garnet mineral cools but is buoyant and light when subject to
heat due to the low melting points.
[Earth] 6. The outer most layer, the crust, is categorized into two
parts, the Oceanic crust and the continental crust. The Oceanic crust is
the smallest part of Earth, only 0.099% of its mass and reaching a
small depth of 0-6 miles (0-10 kilometers). In the beginning of time,
it was possible that this area did not exist for through frequent
volcanic activity does only the crust form. Evidence of this is marked
by the oceanic ridge system, which is a 25,000 mile (40,000-kilometer)
array of many volcanoes which creates layer after layer of new crust at
the rate of 17 km3 per year. The ocean floor is covered in basalt
originating from volcanic activity and as a matter of fact, Iceland and
Hawaii are two island systems that emerged from the accumulated basalt.
7. Continental crust: The second smallest area of the Earth is the
Continental crust, making up only 0.374% of the Earth's mass and
extending a short depth of 0 - 31 miles (0-50 kilometers). Looking at
the percent by composition, the continental crust makes up only 0.554%
of the mantle-crust mass. The layer is composed primarily of
crystalline rocks made of low-density buoyant minerals dominated mostly
by quartz (SiO2) and feldspars (metal-poor silicates). This is the
outer part of the Earth composed essentially of crystalline rocks. The
continental crust and the oceanic crust are also referred to as the
lithosphere because of the cool and rocky conditions that exist in its
chemical composition.
[Non-text portions of this message have been removed]
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