Transcript The Solid Earth - Cloudfront.net

The
Earth is:
• The third planet in our Solar
System;
• A terrestrial planet;
• Composed of a rocky planet
with a gaseous atmosphere
The study of the Earth is called
Earth Science. Earth Science
contains many disciplines
including:
a. atmospheric sciences
b. geology (both physical & historical)
c. hydrology
d. oceanography
e. meteorology & climatology
f. astronomy
 The
Earth was formed at the same time as
the other planets in our Solar System.
 The
theory as to the formation of our
planet is called the Nebular Hypothesis.
 This
hypothesis says that our solar
system evolved from an enormous
rotating cloud called the solar nebula.
 The
nebula was composed mostly of
hydrogen and helium.
 About
5 billion years ago, the nebula
began to contract.
 It
assumed a flat, disk shape with the
protosun (pre-Sun) at the center.
Next,
the inner planets
(terrestrial) begin to form from
metallic and rocky clumps.
Then, the larger outer (Jovian)
planets began forming from
fragments with a high percentage
of ices.
A
B
C
D
E
But……. how was the
Earth (specifically
formed!?!?!?!?!
 As
Earth formed, the decay of radioactive
elements and heat from high-velocity
impacts caused the temperature of the
Earth to increase.
 Denser
materials coalesced or became
concentrated toward the interior or core.
 Lighter
rocky components floated
outward…..toward the Earth’s surface.
 Next,
gaseous material escaped from
Earth’s interior (through volcanoes) to
produce the primitive atmosphere.
 The
primitive atmosphere was made of
methane, ammonia and carbon dioxide.
There was NO free oxygen (O2) because it
is too reactive.
The
Earth is composed of
many different spheres. The
different spheres describe
different parts of our Earth.
The Earth’s Spheres!!!!
The
hydrosphere contains:
• All the water on the planet
including the liquid water
(oceans, lakes, rivers), the
groundwater, the glaciers and
ice caps, and the water found in
the atmosphere.
The
glaciers and the ice-caps
are also called the
cryosphere.
 The
oceans are the largest part of the
hydrosphere!
 They
make up 71% of the Earth’s surface.
 97%
of the hydrosphere is found in the
oceans.
 The
oceans are marine or salt water.
The
atmosphere is the thin gaseous
layer that surrounds our planet.
It
is comprised of 78% Nitrogen (N2),
21% oxygen (O2), 0-4% H2Ov, 1%
argon (Ar), and .038% carbon
dioxide (CO2)
The
gases are held close to the
Earth’s surface by gravity!
The
atmosphere is divided into
layers: troposphere, stratosphere,
mesosphere, thermosphere and then
the exosphere.
The
geosphere is part of the Earth’s
major spheres.
The
geosphere is made of the Earth’s
interior, rocks/minerals, and
landforms such as mountains.
The
geosphere is made of
four parts:
• Crust (two types: oceanic
and continental)
• Mantle
• Outer Core
• Inner Core
The
biosphere is the area on
Earth where life can possibly
be found. It covers the upper
geosphere, the hydrosphere,
and the lower atmosphere.
Let’s
explore the Solid
Earth’s layers in more
detail!
The
inner core is the innermost layer
of the Earth.
The
inner core is made of iron (80%)
and nickel.
It
is extremely hot… about 5 000⁰ C.
Even
though the inner
core is SO hot, it is a
solid. Why is it a solid?
The
inner core extends from
6,378 km (the center of the
earth) to 5,150 km (the
bottom boundary of the outer
core).
The
inner core is the
densest part of the
Earth. The density is 15
3
g/cm
The
existence of an inner core
that is distinct from the liquid
outer core was discovered in
1936 by seismologist Inge
Lehmann using observations of
earthquake-generated seismic
waves that partly reflect from its
boundary and can be detected
by sensitive seismographs on the
Earth's surface.
Outer
Core!
The
outer core is the next
layer of the Earth.
The
outer core mainly
consists of iron and nickel and
about 10% sulphur and
oxygen.
The
temperature in the outer
core is about 4 500ºC.
Because
of this high
temperature, the outer core is
molten or liquid.
The
density of the outer core is
11g/cm³.
The
outer core extends from
5,150 km (the boundary with
the inner core) to 2, 900 km
(the boundary with the
mantle) below the earth's
surface.
The
liquid outer core spins (because
of convection & the Earth’s rotation).
The
inner core does not spin
because it is a solid.
So
the outer core spins around the
inner core.
This
spinning causes the earth's
magnetic field.
Magnetism
has been used by sailors
to navigate the seas for thousands of
years.
Magnetism
also influences electroparticles outside the atmosphere of
the earth (>37,000 miles into space).
The Mantle!
The
mantle is the largest part
of the earth’s structure. It
makes up 80% of the volume
and 70% of the mass of the
Earth!
The
mantle extends from 2,900 km to
~65 km.
The
density of the mantle ranges
from 5 g/cm3 (lower mantle) to 4
g/cm3 (upper mantle)
Element
Amount
Compound
Amount
O
44.8
Si
21.5
SiO2
46
Mg
22.8
MgO
37.8
Fe
5.8
FeO
7.5
Al
2.2
Al2O3
4.2
Ca
2.3
CaO
3.2
Na
0.3
Na2O
0.4
K
0.03
K2O
0.04
Sum
99.7
Sum
99.1
The
temperature of the mantle
ranges from 3000⁰C near the
outer core to about 750⁰C near
the crust boundary. Pressure
keeps the lower mantle solid.
 The
mantle is mostly solid (because of
high pressure) but contains a liquid
portion called the asthenosphere.
 The
liquid portion (asthenosphere) is
found in the upper mantle. This material
moves by convection and is what causes
plate tectonic movement and
earthquakes!
The
region above the
asthenosphere (upper mantle)
and the entire crust are
collectively called the
lithosphere. This “layer” is solid
and floats on the asthenosphere.
The Crust!
 There
are two types of crust: oceanic and
continental.
 Continental
crust is what makes up the
continents, is thicker and less dense (2.7
g/cm3).
 Oceanic
crust is what makes up the
ocean depressions, is thinner, and more
dense (3.0 g/cm3).
 The
crust is very thin: only 2% of the
volume (and 1% of the mass) of the entire
earth! It extends from the surface to
around 65km deep.
 The
crust is made of igneous,
sedimentary and metamorphic rock.
 Most
of these rocks are made of silicates.
Oxide
Percent
SiO2
60.6
Al2O3
15.9
CaO
6.4
MgO
4.7
Na2O
3.1
Fe as FeO
6.7
K2O
1.8
TiO2
0.7
P2O5
0.1
The
crust is not one solid piece of
rock. It is broken up into pieces
called plates. The plates are made
of the crust plus the upper mantle
(lithosphere). These plates “float” on
the asthenosphere and move.
The
temperature of the crust
increases with depth,
reaching values typically in
the range from about 10°C
(50°F) to 300°C at the
boundary with the underlying
mantle.
 The
deepest hole ever dug is the Kola
Superdeep Borehole, dug by the former
USSR. The hole, SG-3, reached
12,261 metres (40,230 ft) in 1989, and
remains the deepest hole ever drilled.