CPE 3

Question 1

Big Bang Theory

Answer 1

About 10-15 billion years ago, all energy and matter was concentrated in a small area that started expanding with a big explosion called the BIG BANG.
* The expanding, cooling universe first formed subatomic particles and finally small atoms of hydrogen and helium.
* After about a billion years, matter clumped together forming stars and early galaxies, and the universe kept expanding

Question 2

EVIDENCE FOR THE BIG BANG
THEORY
Cosmic Background Radiation or Cosmic
Microwave Background (CMB)

Answer 2

Scientist have found evidence of longwave
background radiation coming from all
directions in the universe. This radiation is
from the Big Bang, and is evidence
supporting the theory. It comes from all
directions with no exact source (no star or
galaxy origin)

Question 3

Doppler Effect /Red Shift

Answer 3

Each element (Hydrogen, H and Helium,
He) gives off electromagnetic radiation.
* This radiation can be observed by the
spectrum of a star (ROYGBIV
Since each element has a specific
spectrum (fingerprint), scientists
can tell what types of elements
are in stars based on their
spectrum
Some of the observed spectra of stars are
shifted toward the red or blue end of the
spectrum. This apparent shift in
wavelength is called the Doppler Effect
This Doppler shift is caused by the motion
of the object emitting the radiation. An
object moving towards the Earth would
have a blue Doppler shift and an object
moving away from the Earth would have a
red Doppler shift
Collective light from the stars in all
galaxies is shifted to the red end of
the spectrum indicating the universe
is expanding.
* The farther away a galaxy is from
Earth, the greater the red shift,
indicating the rate of expansion of the
universe is increasing

Question 4

Galaxies

Answer 4

A collection of billions of stars and
various amounts of gas and dust held
together by gravity is called a galaxy.
* There are over 100 billion galaxies.
* Classified by their shape: elliptical,
irregular, and spiral

Our solar system is part of the Milky Way
Galaxy.
* The Milky Way Galaxy is a spiral shaped
galaxy.

Question 5

COSMIC
INFLATION
THEORY

Answer 5

early universe went under rapid expansion in
space – time
states that the early universe was a rapidly
expanding bubble of pure vacuum energy
did not have any matter or radiation
after the expansion and cooling due to
inflation, the potential energy was converted
into KE of matter & radiation…
then a big bang occurred because of the
extremely hot dense condition of the
matter
seconds after the explosion,
matter began to clump together…
eventually stars were formed, &
then galaxies (the universe
continued to expand up to the
present)

Question 6

1. Homogeneity

Answer 6

of the objects in space –
during expansion period, objects that used to
be in contact or neighboring objects got
farther away from each other…their
composition, however, remained almost intact
this explains further
why the opposite
horizon of the universe
appears to be similar

Question 7

2. flatness or
   smoothness of the universe –

Answer 7

Appearance of flatness or
smoothness of the universe –
the continuous expansion
“dilutes” or gradually loses the
curvature of objects

Question 8

3. Formation of stars and
   star systems in later years –

Answer 8

it asserts that during
expansion, small density
fluctuations happen
(this causes gravity to attract
gas into masses, giving birth to
stars & eventually galaxies,
explaining why the universe
would always look full of
planetary objects instead of
completely empty)

Question 9

STEADY
STATE
UNIVERSE

Answer 9

*this theory acknowledges that
change takes place on a smaller
scale
*proposes that new stars are
continually created at all time at the
rate needed to replace the stars
which have used up their fuel & have
stopped shining

• universe is always expanding
• new matter is constantly
  formed as the universe
  continues to expand
• older bodies eventually became
  out of sight as a consequence
  of their increasing distance and
  rate of recession

*further claims that the
universe has no
beginning or end in time,
& even though it is
expanding, its
appearance remains the
same over time

Question 10

The Basics of Steady State Theory

Answer 10

Who: first proposed by Sir
James Jeans (1920)
* Hermann Bondi, Thomas Gold,
and Sir Fred Hoyle
* When: 1948
* Where: Earth
* What: Proposed the Steady
State Theory
* Why: An alternative theory to
the Big Bang

Question 11

THE LOGIC BEHIND STEADY STATE THEORY

Answer 11

No sudden beginning to universe
* Decrease in density caused by
expansion balanced by
continuous creation of matter
condensing into galaxies
* Maintain forever present
appearance of the universe

Question 12

The Contributions of Steady State Theory

Answer 12

Explains hydrogen
and helium abundance
in the universe
*Contributes to
Wheeler-Feynman
Theory

Question 13

The Refutation Behind Steady State Theory

Answer 13

evidence against the theory began to emerge during the early 1960’s
Distribution of Radio Sources
* 1966: Discovery of Quasars
* Cosmic Background Radiation
Quasars and radio galaxies were found a long way from the sun at far distances in space (and found none nearby) —disproved the idea that similar bodies are created and found everywhere

*the fact that quasars are only found in the early
universe provides strong evidence that the Universe has change over time, distant objects in space are considered ancient and the younger universe are found nearer
— implies that the universe is actually dynamic (not steady)
*In cosmology, this is now considered obsolete

Question 14

The Conclusion

Answer 14

The Big Bang Model prevails present
day
* Steady State theory helped to prove
Big Bang through its testability

Question 15

Any theory to describe the formation of our Solar
System must be consistent with these facts:

Answer 15

1. Each planet is isolated in space.
2. The orbits are nearly circular.
3. The orbits of the planets all lie in
   roughly the same plane
4. The direction the planets orbit
   around the Sun is the same as
   the Sun’s rotation on its axis.
5. The direction most planets
   orbit on their axes is the same
   as that for the Sun.
6. The direction of the
   planetary moon’s orbits is the
   same as that of the planet’s
   rotation.
7. The terrestrial planets are
   very different from the Jovian
   planets.
8. Asteroids are different from
   both types of planets.
9. Comets are icy fragments
   that don’t orbit in the ecliptic
   plane.

Question 16

1

Answer 16

1

Question 17

Nebular Hypothesis
Descartes 1644
Immanuel Kant 1755
Laplace 1796

Answer 17

*Older than 4.56 billion years ago
*Gravity is the cause of “condensation”
of the cloud
*Cloud contracted WHILE spinning faster
*H & He are the most common elements
*H & He collected to form fusion
reactions
Our Sun and the planets began from a cloud of dust
and gas (nebula)
As the cloud contracts under
its own gravity, the Sun is
formed at the center.
The cloud starts to spin and
the smaller it contracts, the
faster it spins.
Conservation of angular momentum
The cloud forms a flattened,
pancake shape.

Question 18

1. Heating

Answer 18

Some energy is radiated away
thermally. The solar nebula becomes
hottest near its center, where much of
the mass collect to form the protosun.
Protosun eventually becomes so hot
that nuclear fusion ignited in its core.

Question 19

2. Spinning

Answer 19

Cloud therefore spins up rapidly as it
contract.
Rotation also ensures not all of material
collapses onto the proto-sun: the greater
the AM of a rotating cloud, the more
spread out it will be along its equator.

Question 20

3. Flattening

Answer 20

Collisions further flatten the
disk.
 Gas moves in random directions
at random speeds. Different
clumps collide & merge, giving
new clumps the average of their
differing velocities.
 Original cloud thus become more
orderly as cloud collapses,
changing the cloud’s original
lumpy shape into a rotating,
flattened disk.
 Similarly, collisions between
clumps of material in highly
elliptical orbits reduce their
ellipticities, making their orbits
more circular.

Question 21

Step 4: Condensation

Answer 21

Formation of planets requires “seeds” - chunks of
matter that gravity can eventually draw
together.
 The process by which seeds were sown is
condensation, when solid or liquid particles
condense out of a gas.
 Condensation is temperature dependent. When
the temperature is low enough atoms/molecules
solidify
T < 2,000 K, compounds of silicates (rock) and nickel iron form.
T < 270 K, carbon compounds, silicates and ices form.
Planetary interiors to Mars
Nebula temperature > 400 K
Made of silicates and metals
Planets beyond Mars
Nebula temperature < 300 K
Made of silicates and ices. Metals include iron, nickel, aluminum. Most metals condense into solid at temperatures of 1000-1600 K. Metals made up <0.2% of the solar nebula’s mass.
Rocks are common on Earth’s surface, primarily silicon-based minerals (silicates). Rocks are solid at
temperatures and pressures on Earth but melt or vaporize at temperatures of 500-1300 K depending on type. Rocky materials made up ~0.4% of the
nebula by mass. Hydrogen compounds are molecules such as methane (CH4), ammonia
(NH3), and water (H2O) that solidify into ices below about 150 K. These were significantly more abundant than rocks and metals, making up ~1.4% of nebula’s mass.
Light gases (H and He) never condense under solar nebula conditions. These gases made up the remaining 98% of the nebula’s mass
Terrestrial planets are made from materials that
constituted ~0.6% of the nebula.
Jovian planets were formed in region where ~2% of
material condensed. They also captured gas (98%).
inner planets have high metal/rock content and few volatile materials.
Size and composition of planetesimals depends on temperature and distance from
Sun.
Inner solar system: Within frost line, only rock and metals can condense. Planetesimals therefore made of rock and metals. Constitute ~ 0.6% of available material by mass. Inner planetesimals therefore grew more slowly. Inner planets are therefore smaller
Outer solar system
* Beyond frost line, rock, metals & ices condensed.
* Planetesimals therefore contain these materials.
* Constitute ~ 2% of available material by mass.
* Outer planetesimals therefore grew more quickly.
* Outer planetesimals are therefore larger.

Question 22

Step 5: Accretion

Answer 22

After condensation, growth of solid particles occurs due to collisions.
Accretion is growth of grains through collisions - the real planet building process.
Larger particles formed from both tiny chondrules about 1 mm in size, and from porous molecular aggregates held together by Van der Waals forces.
Accretion proceeds in two ways:
1. Collisions due to the geometric cross section - direct impacts on ‘seed’ grain.
2. Collisions due to gravitational attraction - sweeping up of material from a region much larger than grain diameter
Inner Planets
Formed slowly due to small amount of metals & rocks in early solar nebula.
Geometric accretion rate and gravitational accretion rate small.
By time inner planetesimals were formed and had significant gravitational fields, the nebula had been cleared out by the solar wind.
no nebular gas then present to capture an elementary atmosphere.
Outer Planets
* Formed less violently.
* Great quantities of ice resulted in large rock/ice cores forming.
* Reason for rapid core growth is that ices have large cross-sectional area
planetesimal graveyard: Asteroid belt is ‘resting
ground’ for collision-evolved planetesimals that were not incorporated into a planet.
Ceres the largest asteroid has a diameter of 940 km
and a mass of ~1021 kg.
A planet probably did not form in this region because of the rapid formation, & resulting large mass of Jupiter.

Question 23

Planetesimal Theory

Answer 23

*Planetesimals (early-stage, immature,
small planets) on the periphery of this
contracting, spinning dust cloud began
to clump together locally.
*Denser materials fell closer to the sun
*Less dense materials (gases) could
escape to greater distances from the
sun e,.g., Jupiter floats in water. Giant planets grow by gas accretion

Question 24

Dualistic Hypothesis (TIDAL)

Answer 24

James Jeans (1917) proposed a
dualistic theory that separated
formation of Sun from formation of
planets.
 Involved interaction between
Sun & a very massive star in
three stages:
1. Massive star passes within Roche Limit
of Sun, pulling out material in the form
of a filament.
2. Filament is gravitationally unstable,
and breaks into series of blobs of
masses greater than the Jeans’
critical mass, and so collapse to form
proto-planets.
3. Planets were left in orbit about the
Sun.

Question 25

Roche
Limit

Answer 25

Roche limit is distance at
which a satellite begins
to be tidally torn apart.
Consider M with 2
satellites of mass m and
radius r orbiting at
distance R. Roche limit is
reached when m is more
attracted to M than to m.
Occurs when Ftidal ≥
Fbinding

Question 26

Jeans’ tidal theory: Difficulties

Answer 26

1. Very massive stars are rare & distant.
   o Probability of massive star coming close
   to another star is therefore very low.
   o Sun’s nearest companion is Proxima
   Centauri.
2. Rotational period of Sun & Jupiter should
   be similar if Jupiter’s material was from
   Sun.
   o Not the case (Psun
   ~ 26 days and Pjupiter ~
   10 hours).
3. In 1935, Henry Russell argued that
   it is not possible for the material
   from the Sun to acquire enough AM
   to explain Mercury, let alone the
   other planets.
4. Spitzer (1939) noted that material
   with solar densities & temperatures
   would give a minimum mass for
   collapse of ~100 times that of
   Jupiter.

Question 27

Beta Pictoris

Answer 27

Young star about 20 million
years old that is located 63
light years away.
-appears to be a
young planetary
system in the
making & supports
the standard model
of solar system birth,
which supposes that
planets accrete
from a disk of dust &
gas surrounding a young star

Question 28

Orion Nebula, giant stellar
nursery ~1600 light years
away

Answer 28

At the heart of the Orion
Nebula lies a complex of
molecular clouds where
abundant star formation is
occurring today.
The clouds are illuminated
by a flood of ultraviolet
light emitted by four bright
stars, collectively called
the Trapezium.
More than 150
protoplanetary disks have
been found in this mosaic
of HST images.

Question 29

How old is the Earth?

Answer 29

4.56 billion years old, older than the moon which is 4.5 billion years old.

Question 30

What was happening on Earth at…?

Answer 30

4.56 and 4.5 by: Accretion to create
the first earth… a
“magma” earth (100
million-year-period)
4.5 by: Earth was hit by a giant
bolide (before 4.47 by) that
remelted it and led to the
formation of the moon
4.5 and 4.4 by: Mainly cooling and
differentiation: Gravity
pulled the denser
materials toward the
core when the Earth was
still molten

Question 31

What was happening on Earth at…?

Answer 31

4.56 and 4.5 by: Accretion to create
the first earth… a
“magma” earth (100
million-year-period)
4.5 by: Earth was hit by a giant
bolide (before 4.47 by) that
remelted it and led to the
formation of the moon
4.5 and 4.4 by: Mainly cooling and
differentiation: Gravity
pulled the denser
materials toward the
core when the Earth was
still molten

Question 32

THE FIRST
ATMOSPHERE

Answer 32

Early atmosphere would have been similar to the Sun–mainly H & He, but this atmosphere was lost quickly for 2 reasons:
(1) Gravity of the modest size earth was not strong enough to prevent such light gases from escaping
to space, particularly since the early earth was hot!
(2) Appears that around 30 m.y. after the earth’s formation, it was struck by a large object, the size of Mars.
Result: the origin of the moon & loss of earth’s early H, He atmosphere
EARTH IS LITERALLY HOT - surface of the earth during this period was extremely hot with numerous volcanoes
- it was under near constant bombardment by objects of varying sizes
- slowly, it started to cool down & the
second atmosphere began to form.

Question 33

EARTH’S SECOND ATMOSPHERE

Answer 33

A new atmosphere was established by the
outgassing of volcanoes…the mixture of gases
was probably similar to those of today’s
volcanoes:
H20 vapor (roughly 80%)
CO2 (roughly 10%)
N2 (few percent)
Small amounts of CO, HCL, HS (Hydrogen
Sulfide), SO2, CH4 (Methane), Ammonia (NH3), &
other trace gases.
Virtually no oxygen in that second
atmosphere. Thus, no ozone layer, so ultraviolet
radiation flooded the earth’s surface. With a huge influx of water vapor and the cooling of the planet, clouds and earth’s oceans formed. At that time the sun was about 30% weaker than today…why
didn’t the earth freeze over?
The apparent reason: so much CO2 so there was a very strong greenhouse effect.

Question 34

THE RISE OF OXYGEN & THE THIRD ATMOSPHERE

Answer 34

In the first two billion years of the planet’s evolution, the atmosphere acquired a small amount of oxygen, probably by the splitting of water (H20) molecules by solar radiation.
The evidence of this oxygen is suggested by minor rust in some early rocks. The oxygen also led to the establishment of an ozone layer that reduced UV radiation at the surface. With the rise of photosynthetic bacteria (cyanobacteria) and
early plants, oxygen levels began to rise rapidly as did indications of rust in rocks Between 2.5 billion years ago to about 500 bya, 02rose to near current levels. While O2 was increasing, CO2 decreased due to several reasons:
(1) In photosynthesis CO2 is used to produce organic matter, some of which is lost to the system (e.g., drops to the bottom of the ocean or is buried)
(2) chemical weathering, which removes CO2. At first this happened without life, but the process was sped up tremendously by living organisms. Marine organisms would incorporate carbonate into their
shells, which would fall to the ocean bottom when they died— thus, removing them from the
system for a long time.
The bottom line…CO2 was being removed from the system.
MORE CHANGES
Sulfur compounds were taken out of the atmosphere as acid rain and were deposited on the ground as sulfates. N2 gas increased slowly but
progressively since it was relatively inert. Current composition of the atmosphere was established approximately a billion years ago.
A PROBLEM
With lower CO2levels the earth became more susceptible to ice ages when solar radiation decreases due to orbital variations. It appears that around 750-550 million years ago the earth cooled
down and became nearly entirely glaciated.

Question 35

HOW DID WE GET UNFROZEN?

Answer 35

Volcanoes were still putting CO2
into the
atmosphere.
Weathering was greatly reduced…since
little liquid water.
So CO2
increased until the greenhouse
effect was so large the earth warmed up.
Once warming started it would have
happened very rapidly.

Question 36

THE LAST 500 MILLION YEARS

Answer 36

The climate has not been constant, with
warm periods interrupted by ice ages.
Much of the variability forced by changing
solar radiation due to periodic changes in
the earth’s orbital characteristics and tilt
(Milankovitch cycles) and major volcanic
eruptions (putting out massive CO2
that
caused warming.

Question 37

The Hydrosphere

Answer 37

The hydrosphere is the total amount of water found on Earth. This includes water in various forms—- whether in ice, vapor, or liquid, found on or below the surface of the Earth and in gas in atmosphere. Water covers 70% of the entire surface of Earth, and most of it is ocean water. Only 3 % of Earth’s water is fresh: two-thirds are in the form of ice, and the remaining one-third is present in streams, lakes, and groundwater. The oceans are important sinks for CO2 through direct exchange with the atmosphere and indirectly through the weathering rocks. Heat is absorbed and redistributed on the surface of the Earth through ocean circulation.

Water has been associated with the existence of life. When water or traces of water are found in other planets, the possibility of life is always speculated. It is critical component of most organisms that drying up would mean dying.

The Importance of Water

1. Water could be in liquid form, not just solid and gas.
2. Water has a neutral pH.
3. Water is high specific heat.
4. Water is a good conductor of heat and energy.
5. Water is a universal solvent.

Water circulates everywhere on Earth. This circulation is made possible by the interaction of energy and matter that allows the transformation of water from one phase to another, allowing it to circulate and travel to different regions of Earth. Because of the water cycle, different life processes are maintained.

All waters found on Earth are natural but not everything is considered safe for drinking. In fact, less than 35 of the world’s waters are considered potable. The waters on Earth are divided into two groups: Surface water and groundwater. Surface water, as the name implies, is water found on Earth’s surface. Surface water and groundwater differ in the types and amount of minerals found in them. Surface water may be either marine water and freshwater. Marine water has higher salt content and is found in large bodies while freshwater is those have lower salt content.

Groundwater is water beneath Earth’s surface where there are spaces on the soil or fractures in rocks.

The aquifer is the underground layer of water-bearing rocks and it acts as a reservoir for groundwater and may contain large amounts of minerals such as magnesium, calcium, etc.

Question 38

The Biosphere

Answer 38

The biosphere is the subsystem that comprises all living things, including those which have not yet been identified. In fact, there are more life-forms unknown to humans than those that have been identified. Life exists in all the subsystems of Earth- on land, in water, and in air.

It is the regions of the surface, atmosphere, and hydrosphere of the earth (or analogous parts of other planets) occupied by living organisms.

• Biosphere is a closed system
  that makes up all the living
  components of Earth.
• The pyramid is constructed
  according to the rate at
  which food material(in the
  form of energy) passes
  through the food chain
• It covers all ecosystems - from the soil to the rainforest, from the mangroves to coral reefs, and from the plankton-rich ocean surface t the deep sea.
• For the majority of life on Earth, the base of the food chain comprises photosynthetic organisms. During photosynthesis, CO2 is sequestered from the atmosphere, while oxygen is released as a by-product. The biosphere is a CO2 sink, and therefore, an important part of the carbon cycle.
  -Sunlight is necessary for life.

THE ORIGIN OF THE BIOSPHERE

Life on Earth is presumed to have begun around 3.9 million years ago from a single primitive living creature. How it started and evolved up to this time. Therefore, many theories emerged that attempt to explain the origin of life on Earth.

1. The theory of primordial soup. Scientists have held on to the theory of primordial soup. Scientists have held on to the theory of the primordial soup, which explains how life began on Earth. It states that life began from nonliving matter such as simple organic compounds. It was believed that the primitive Earth contained chemicals such as methane, water, ammonia, and hydrogen gas that accumulate in a soup at certain areas viable for transformation. Over time, the first known creatures to have inhabited Earth were the single-celled microorganisms, bacteria, and archaeans.
2. Deep-sea vent theory. This theory presupposes that life began to on the surface of Earth but deep down in the sea in areas known as marine hydrothermal vents. Hydrothermal Vents release boiling hot fluids mixed with toxic chemicals and heavy metals. Hydrogen sulfide is the main compound spewed out from cracks or fissures on the ocean floor. Certain bacteria or primitive microbes grow around the vents. The bacteria absorb hydrogen sulfide that streams from the vents to create simple sugars from their food in a process known as chemosynthesis. In 1990, the discovery of nanotubes ( organisms smaller than bacteria that contain DNA and live rocks) and the subsequent discovery of an entirely new ecosystem that exists in the deep-sea vent support this theory which was proposed by Thomas Gold (1920-2004) in his paper entitled ‘The Deep Hot Biosphere (1992).
3. Panspermia. This hypothesis proposes that life on Earth actually began somewhere in the universe. Life - forms could have been carried by meteorites, asteroids, or comets as they made a cosmic impact on Earth.

The biosphere is a closed system that makes up all the living components of Earth. In this system an organism can consume another organism to allow energy to circulate to the ecosystem (see Figure 2.8.1 ). Life exists in all the subsystems of Earth— on land ( geosphere ), in water ( hydrosphere ), and in air ( atmosphere ).

A key component to Earth’s systems, the biosphere interacts and exchanges matter and energy with the other systems. It helps drive the biogeochemical cycling of carbon, nitrogen, phosphorous, sulfur, and other elements. Through an ecological point of view, the biosphere encompasses Earth’s ecosystem and performs all manner of biological functions such as respiration and photosynthesis.

Question 39

GEOSPHERE

Answer 39

Scientists divide the Earth into three
layers based on composition
(chemical sections)
* Crust – the thinnest layer of the Earth (5-
20km thick) made entirely of light elements
like silicon
* Mantle – makes up 68% of the earth’s mass,
(2900km thick) made of rocks of medium
density
* Core – the innermost layer, has a radius of
3400km and composed of the densest
elements such as nickel and iron

Question 40

The Crust

Answer 40

• The crust makes up less
  than 1% of the Earth’s
  mass.
• There are two types of
  crust:
  – Continental crust, and
  oceanic crust.
  *Is the outermost solid part of the earth,
  normally about 8-40 kms thick.
  *It is brittle in nature.
  *The thickness of the
  crust under the oceanic
  and continental areas
  are different. Oceanic
  crust is thinner (about
  5kms) as compared to
  the continental crust
  (about 30kms).
• Continental
  crust is about 30-
  35 km thick.
• It is also made up
  of lightweight
  and low density
  materials.
• Oceanic crust is
  much thinner –
  it’s only about 5
  km thick!
• It is also made up
  of heavier and
  denser materials.
  Major constituent elements:
  *Silica (Si) and Aluminium (Al) and thus, it is often termed
  as SIAL (Sometimes SIAL is used to refer Lithosphere, which is
  the region comprising the crust and uppermost solid mantle,
  also).

Question 41

The Mantle

Answer 41

• The mantle is about 2900 km thick.
• It is made up of dense materials, which are
  rich in iron.
• The mantle is semifluid; the molten rock
  flows very slowly, which lets the solid
  plates move on top.
• The discontinuity between the crust and
  mantle is called as the Mohorovicic
  Discontinuity or Moho discontinuity.
• Nearly 84% of the earth’s volume and
  67 - 68% of the earth’s mass is
  occupied by the mantle.
• The major constituent elements of the
  mantle are Silicon and Magnesium and
  hence it is also termed as SIMA
  The Lithosphere: * The uppermost solid
  part of the mantle and
  the entire crust
  constitute the
  Lithosphere.
• The lithosphere is
  cool, solid and rigid.
• It is divided into many
  smaller pieces called
  tectonic plates.
  The Asthenosphere: * is a highly viscous,
  mechanically weak and
  ductile, deforming region
  of the upper mantle which
  lies just below the
  lithosphere
• is semi-fluid, molten rock
• allows the tectonic plates
  to move on top
  The Asthenosphere
  This motion is essential to our Earth‘s appearance. The asthenosphere is
  the main source of magma and it is the layer over which the lithospheric
  plates/ continental plates move (plate tectonics).
  *The discontinuity
  between the upper
  mantle and the lower
  mantle is known
  as Repetti Discontinuity.
  *The portion of the
  mantle which is just
  below the lithosphere
  and asthenosphere, but
  above the core is called
  as Mesosphere.

Question 42

The Core

Answer 42

*It is the innermost layer surrounding the earth’s
center.
*The core is separated from the mantle by
Guttenberg’s Discontinuity.
*It is composed mainly of iron (Fe) and nickel (Ni)
and hence it is also called as NIFE.
*The core is the densest layer of the earth with its
density ranges between 9.5-14.5g/cm3.
Outer Core
* The outer core is
composed of dense
liquid metallic elements.
* Mainly nickel and iron.
Inner Core
* The inner core is
composed of solid
nickel and iron.
* This is due to the
immense pressure found
at the center of the
Earth
*The discontinuity
between the upper
core and the lower
core is called
as Lehmann
Discontinuity.
*Barysphere is
sometimes used to
refer the core of the
earth or sometimes the
whole interior

Question 43

The Atmosphere

Answer 43

• N - most abundant gas, does not
  react readily with other
  substances.
• O - reacts chemically as fires
  burn, iron rusts, and plants and
  animals respire.
• CO2
• which by some models
  formed as much as 80 percent
  of Earth’s early atmosphere, is
  a trace gas in the modern
  atmosphere, with a
  concentration of only 0.035 %

Question 44

Troposphere

Answer 44

• “Tropos” means
  turning or changing
• layer of air closest to
  Earth & considered the
  densest among the layers
  because of the weight of
  all other layers
• virtually all of the water
  vapor & clouds exist in
  this layer
• Temperature goes from
  warm to cold as you
  increase in altitude.
• This is where all weather
  occurs.
• The tropopause is the
  boundary between the
  troposphere and
  the stratosphere above.

Question 45

Stratosphere

Answer 45

• “Strato” means layer
  or level
• Contains the Ozone
  layer (serves as shield
  against the sun’s UV
  radiation)
• From 10km to 50km
  above sea level.
• Planes often fly here.
• Temperature goes up as
  you rise in altitude due to
  the ozone absorbing the
  suns heat.
• This boundary between
  rising and falling
  temperature is
  the stratopause, the
  ceiling of the
  stratosphere.

Question 46

Mesosphere

Answer 46

• “Meso” means
  middle & is the
  middle layer of the
  atmosphere.
• Protects the earth
  from planetary
  debris (e.g.
  meteoroids)
• Temperature goes
  down as altitude
  goes up.
• The ceiling of the
  mesosphere is
  the mesopause.
• Considered the
  coldest region

Question 47

Thermosphere

Answer 47

• “Thermo” means heat.
• considered the hottest
  layer because it absorbs
  highly energetic heat from
  the sun
• Temperatures reach up to
  1,800 degrees Celsius or
  3,272 degrees Fahrenheit.
• 80km above sea level and
  has no definite end.
• As you increase in
  altitude, temperature
  goes up.
• Here the atmosphere
  absorbs high-energy
  X-rays and ultraviolet
  radiation from the
  Sun.

Question 48

Ionosphere

Answer 48

• from the lower part of
  the thermosphere
• Called ionosphere
  because suns energy
  heats molecules to
  become ions.
• Temperature goes up
  as you increase in
  altitude.
• Known for causing
  aurora borealis.
• Most collision of oxygen
  and nitrogen particles are
  electrically charged by the
  solar wind.
• Energy released during
  collisions causes the
  colorful glow around the
  poles called auroras.
  NORTHERN LIGHTS/aurora
  borealis– witnessed in
  northern regions like Arctic &
  Northern Canada
  Aurora australis – seen in
  the Southern regions like
  Antarctica and Southern
  Australia

Question 49

Exosphere

Answer 49

• The uppermost layer
  of the atmosphere
• Layer of very diffuse
  gas that overlies the
  thermosphere and
  thins upward into the
  vacuum of space
• Not considered as
  another layer but it
  separates Earth’s
  atmosphere from
  interplanetary space.
• Second layer of the
  thermosphere.
• Satellites orbit Earth in
  this layer.

Question 50

Interactions among the Earth’s
spheres change the spheres to
differing degrees.

Answer 50

These impacts can be single events,
temporary changes, or ongoing change
Single event example: meteorite impact that
causes massive global extinction
Ongoing, steady process (example: Erosion)

Question 51

The Carbon Cycle

Answer 51

• Biogeochemical cycle- compound is
  changed and moved throughout the
  Earth’s spheres
• Carbon is commonly called the
  “building block of life”
• Carbon is not just a solid- it forms
  gases such as CO2 and Methane
  Carbon Into the Atmosphere
• Living things breathe it out
• Carbon based things (i.e. trees) burn
• Diffuses out of oceans
• Volcanoes erupt– Number 1 source of
  CO2 into the atmosphere
  Carbon From the Atmosphere
• Oceans dissolve 40% of CO2 in the
  atmosphere from fossil fuels
• Wave action dissolves CO2 into ocean
• Photosynthesis- plants breathe it in, and
  breathe out oxygen (phytoplankton do
  this in ocean water)
  Other ways CO2 is shared…
• Carbon stored in plants is passed on
  to another organism when eaten
  (food chain)
• Organisms die and decomposition
  puts carbon into the ground creating
  fossil fuels (oil, coal, etc.)

Question 52

The Energy Cycle (Energy
Budget)

Answer 52

• Water and carbon
  Cycles are like wheels
• Energy Cycle is like a
  balance
  – Energy that comes in
  must equal the energy
  that comes out
• about 40% is reflected back into
  space without being changed
• the remaining energy is used within
  the Earth system
• as it moves through the system, it is
  changed. With every change, a little is
  lost to the system.

Sources of Earth’s Energy
1. Solar energy- 99.895 %
* Comes from nuclear fusion reactions in the
sun
* Drives wind, ocean currents, waves
* Source of energy that causes rocks to
weather forming soil

2. Geothermal energy- 0.013 %
   * Comes from the Earth as radioactive
   materials decompose
   * Drives the movement of the continents,
   powers geysers, earthquakes, and
   volcanoes
3. Tidal energy- 0.002 %
   * The result of the pull of the moon
   on the Earth’s oceans
   * Slows down Earth’s rotation and
   causes the oceans to bulge

Question 53

The Effects of Earth’s Surface

Answer 53

• Albedo is the percentage of energy that is
  reflected back into space without being
  changed
• Earth’s average albedo: 30%
• Forest has low albedo: 5-10%
• Desert has high albedo: 50%
• Fresh snow: 80-90%
• Humans can alter the albedo of an area,
  which affects the Earth’s energy budget
• We can burn fossil fuels which puts CO2 in
  the air, or plant trees, which takes CO2 out
  of the air
• Damming a river lengthens the amount of
  time it takes water to go through the
  water cycle

Question 54

Geologic Processes of Earth

Answer 54

• describe the natural forces that influence
  the shape and structure of the planet
  -has two categories: EXOGENOUS (external)
  processes & ENDOGENOUS (internal) processes

Question 55

EXOGENOUS
PROCESSES (occur on or near the surface
of the EARTH)

Answer 55

1. WEATHERING – the
   disintegration of rocks, soils,
   & minerals together with
   other materials through
   contact with Earth’s
   subsystems
   Physical
   weathering –
   breakdown of
   rocks by
   mechanical forces
   concentrated along
   rock fractures
   Chemical weathering
   – process by which
   rocks break down by
   chemical reactions
2. EROSION
   –
   process by which
   Earth’s surface is
   worn away by
   wind, water, or ice
   - takes place when there is
   rainfall, surface runoff,
   flowing river, seawater
   intrusion, flooding,
   freezing, thawing,
   hurricane, wind, etc.
3. MASS
   WASTING
   –
   movement of
   material on a
   downslope
   terrain due to
   gravity
   - usually happens in
   slopes, is dangerous,
   and may occur in
   areas that can trigger
   mass movement
   a. Debris
   flow
   b. Mud
   flow
   c. Slumps
   - move down from higher elevations
   without help of water
   - slowly moving of combined soil &
   water down the mountain
   - slow downslope movement of
   loosely consolidated rock & soil
   layers
4. SEDIMENTATION –
   accumulation of
   materials such as soil,
   rock fragments, and soil
   particles settling at the
   bottom
   -usually occurs
   in stream and
   sea erosion

Question 56

ENDOGENOUS
PROCESSES
- caused by forces from
within or in the interior

Answer 56

1. MAGMATISM –
   happens when magma
   is generated & develops
   into igneous
   (magmatic) rocks
   can take place
   either under the
   surface or on the
   surface of Earth
   to become part of
   the crust
2. VOLCANISM/
   PLUTONISM – process
   that usually happens
   after the magma is
   formed
   Magma tries to
   escape from the
   source through
   openings such as
   volcanoes or
   existing cracks on
   the ground
3. METAMORPHISM –
   process of changing the
   materials that make up
   a rock
   2 types:
   Contact
   metamorphism
   (change because
   of heat) &
   regional
   metamorphism
   (happens in a
   larger area)
   TYPES OF STRESS
   INFLUENCING
   ROCK
   BEHAVIOR
4. SHEARING –
   some portions of
   a plate may
   break away in
   diff. directions
5. COMRESSION –
   rocks push or
   squeeze against
   one another
   where the stress
   produced is
   directed toward
   the center
6. TENSION –
   rocks are
   pulled apart
7. CONFINING –
   crust becomes
   compact, making
   it look smaller

Question 57

CONTINENTAL DRIFT THEORY

Answer 57

Alfred L. Wegener
* Geologist Alfred Wegener
noticed similar rocks & fossil
remains were found on
continents which seemed to
fit together
* He called this “super”
continent called Pangaea
* In 1912 Wegener
published the
first version &
died defending
his theory

Question 58

CONTINENTAL DRIFT IN DOUBT

Answer 58

Why didn’t people believe in continental drift?
* People couldn’t imagine how the earth could
be millions of years old
* People couldn’t imagine a force great
enough to move the continents
* He could not find the force that was causing the
continents to drift.
BUT by the 1960’s evidence would prove
continental drift is somehow TRUE and….
the story continues…

Question 59

Seafloor Spreading

Answer 59

Harry Hess - 1960s
– new ocean basins form from volcanism
– ocean floor forms IN BETWEEN pieces that have
split
– The Sea floor spreading theory states that new
ocean crust is being created at mid-ocean ridges
(which are large mountain chains underwater)
and destroyed at deep-sea trenches.

Question 60

What causes sea floor spreading?

Answer 60

Convection Currents occur within the mantle of the earth
when hot magma rises and cool magma sinks.
- Arthur Holmes (British geologist) suggested the idea of thermal
convection as the driving force for the movement of continental
This is a model of sea floor spreading at a
divergent boundary called a mid ocean
ridge.

Question 61

What are Plates?

Answer 61

The Earth’s crust and
upper mantle
(Lithosphere) are
broken into sections
called plates
A section of the lithosphere that slowly
moves over the asthenosphere, carrying
pieces of continental and oceanic crust.
Plates move around on top of the mantle like rafts

Question 62

What is the Theory of Plate Tectonics?

Answer 62

The theory that pieces of Earth’s lithosphere are in
constant motion, driven by convection currents in the
mantle.
* Plates move
slowly in
different
directions
❑Cause different
geologic events
(like
earthquake,
volcano, etc.)
Convection Currents in the mantle move the plates as the core heats
the slowly-flowing asthenosphere (the elastic/plastic-like part of the
mantle).
FAULT – Breaks in Earth’s crust where rocks have
slipped past each other.

Question 63

Divergent Boundaries

Answer 63

A plate boundary where two plates move away from
each other
Rock gets THIN in the middle as it is
pulled apart.
This STRESS is called tension.
A Normal Fault (fault is a break in Earth’s crust)
Rock drops down as it breaks
* A geologic feature or
event…
May form RIFT
VALLEYS on continents
SEA-FLOOR SPREADING
in the ocean
Happens on land
& under H2O
Features of Divergent Boundaries
* Mid-ocean ridges
* rift valleys
* fissure volcanoes

Question 64

Convergent Boundaries

Answer 64

A plate boundary where two plates move
towards each other.
Boundaries between two
plates that are colliding
* Places
where
plates crash
(or crunch)
together or
subduct
(one sinks
under)
What happens when the rock is squeezed
from the Stress of Compression?
* A REVERSE FAULT
* Rock is forced upward as it is squeezed.

Question 65

Type 1 Convergent Boundary

Answer 65

Ocean plate colliding with a less dense
continental plate
Subduction Zone: The process by which
oceanic crust sinks beneath a deep-ocean
trench and back into the mantle at a
convergent plate boundary.
VOLCANOES
occur at
subduction
zones
Example: Andes Mountains, South America

Question 66

Type 2 Convergent Boundary

Answer 66

• Ocean plate colliding with another ocean plate
• The less dense plate slides under the more dense
  plate creating a subduction zone called a TRENCH
  Example: Aleutian Islands, Alaska

Question 67

Type 3 Convergent Boundary

Answer 67

• A continental plate colliding with another
  continental plate
• Have Collision Zones:
  –A place where folded and thrust faulted
  mountains form.
• May form Mountain Ranges.
  These are Folded Mountains, like the Himalayas or
  the Rockies.

Question 68

Transform Boundaries

Answer 68

A plate boundary where two plates move past each
other in opposite direction.
* Rock is pushed in
two opposite
directions (or
sideways, but no
rock is lost)
* This stress is
called SHEARING
* May cause
Earthquakes
when the rock
snaps from the
pressure.
* A famous fault @
a Transform
Boundary is the
San Andreas Fault
in California.
What happens when the rock is sheared
(or “cut”) from the Stress of Shearing?
* A STRIKE-SLIP FAULT
* Rocks on each side of the fault slip past
each other as they break.

Question 69

Scientists

Answer 69

In 1956, Abraham Ortelius (1527- 1598) observed and presupposed that the shapes of the continents on both sides of the Atlantic Ocean seem to connect to each other. It was as if Africa was torn away from Asia and Europe. With the absence of valid measurements and proofs, the only speculation he could provide was that earthquakes and flooding may have made the separation possible.

As early as 1929, Arthur Holmes (1890- 1965), a British geologist, suggested the idea of thermal convection as the driving force for the movement of the continents. The concept of thermal convection, as Holmes put it, is based on the fact that as a substance is heated, its density decreases and rises to the surface until it is cooled and then sinks again. the repeating process of heating and cooling may produce a current that is strong enough to make the continents move.

Holmes further suggested that thermal convection works like a “ conveyor belt “ where the pressure that goes up could break apart a continent. The broken pieces can be carried by the same currents to opposite directions. In the later years, the concept of thermal convection was changed to mantle convection currents to specify that the heat is actually radiating from the mantle.