chapter 1 Flashcards
(19 cards)
Define Internal Processes
Occur due to the internal heat inside the Earth due to the movement of lithospheric plates. Affecting Earth’s surface by shaping its relief feature
Define external processes
Powered by solar energy. External processes affect Earth’s surface by shaping the relief created by internal processes using external agents such as rivers and streams, groundwater, ice, etc.
Age of the universe
13.7 Ga (billion years)
What is the Big bang theory?
Cosmic explosion that birthed the universe, forming Hydrogen gas and then helium formed.
Define Nucleosynthesis
Nuclear fusion in stars where more helium and heavier elements from Lithium to Iron
Define Supernovae
Steller explosion and synthesis of elements heavier than iron (Fe=26)
What is the Nebular Hypothesis?
The solar system’s origin can be traced back to a rotating cloud of dust and gas (H and He). The diffuse, slowly rotating cloud contracted under the force of gravity. This accretion (agglomerate) accelerated the rotation of particles, and the faster rotation flattened the cloud into a disk.
What are nebula?
hot rotating clouds of H and He gas and cosmic dust. In nebula, these gases start losing heat becoming smaller but slightly heavier masses, thus colliding by gravity together to form larger but denser masses with time. Therefore, the initial volume of gas masses decreases, and their density increase, allowing gravitational attraction between them to collide and join each other.
How did planets and the moon form?
As particles of dust in the planetary nebula encountered one another, they often stuck together (accretion) due to electrostatic forces, forming larger and larger aggregates called planetesimals. As clumps of materials became larger, gravity forces replaced electrostatic attraction. Planetesimals fell into one another forming planet-sized bodies. As nuclear fusion became the sun’s dominant power source, atoms on its surface became energized to the point that they began flying off of the sun’s surface as solar wind. This wind swept the inner solar system clean of gas and dust. The accretion of new planetesimals stopped. Mars-sized planetesimal hit the Earth about 4.5 Ga ago, leading to the formation of the Moon
What was the role of the solar wind?
1- Swept the inner solar system clean of gas and dust
2- forms the asteroid belt
3- separates inner and outer planets
What are the planetary types and what are they made of? (describe them)
1- Inner (terrestrial) planets: small rocks and metals, small atmospheres formed in the inner solar system
2- Outer (jovian) planets: large (10 to 100 times size of the Earth), H and He, ice and volatile substances, rocks and metals, formed away from the sun so that atmospheres of H and He can be trapped
3- Asteroid belt: between Mars and Jupiter, remnants of the primitive material formed during the Big Bang
4- Meteorites: materials left from the formation of the solar system (4.5 Ga old). The sun gravitational field contains:
- Comets: frozen gases and cosmic material
- Meteroids: small clusters of rocks
- Cosmic dust: remnants of the big bang
Give an example of a meteorite
Barringer Meteor Crater in Arizona
State and describe the stages of formation (evolution of the Sun).
1- Gravitational contraction: initially, as gas molecules (H and He) and particles of cosmic dust plunged toward the center to form the proto-sun (primitive sun), it shone brightly from the heat produced by their friction
2- Nuclear fusion: when the pressure at the core of the proto-sun reached a critical point (of increasing compression), proto-sun material got denser and hotter, and hydrogen atoms began to collide and fuse to form helium, releasing thermo-nuclear energy. As less stuff fell into the new sun, nuclear fusion replaced gravitational contraction as the primary source of solar heat. Mass is converted to energy (sunshine)
What happened between the formation of the Solar System and the formation of the earliest rocks?
Sources of heat for the early Earth include:
1- Gravitational heating:
- Earth’s interior: uniform and undifferentiated
- Earth’s exterior: being heated by impacting planetesimals yielding a magma ocean kilometers deep
2- Radiogenic heating caused by decay of radioactive isotopes inside the Earth
2- Giant Impact of a Mars-size planetesimal. All moon rocks are very depleted in volatile materials compared to Earth rocks. The remaining non-volatile stuff accreted to form the moon (4.5 Ga)
Describe the early history of the Earth.
Period of differentiation in which the effect of heat sources transforms random chunks of primordial matter into a body whose interior is divided into concentric layers that differs both physically and chemically. The net effect of all heat sources was to melt or soften the Earth’s interior enough to allow lighter materials to rise and heavier materials to sink. Lighter materials (mostly rocks) rise to the surface and heavier materials (mostly metals) sink to the center. The sinking caused more gravitational heating, accelerating the process.
Differentiation leads to three basic compositional layers of the Earth:
1- Crust: light rocks rich in Si and Al (felsic), between oceanic 10 km to continental crust 40 km thick
- continental (low density, granodiorite, ~40 km thick)
- oceanic crust (high density, basalt, ~10 km thick)
2-Mantle: starts at the base of crust down to 2900 km. Consists of dense rocks rich in Mg and Fe (mafic). It is a solid zone. Upper and lower mantle.
3-Core (outer and inner core at 5150 km): extends from 2900 km to the center of the Earth at 6278 km. Consists of metals made up of about Fe 90% + Ni 8% + other elements 2%
- outer core: liquid
- inner core: solid
Discuss the early life on Earth
The first atmosphere had little or no free oxygen in it. Single-celled blue-green algae appeared in significant numbers around 2.7 Ga and modified the atmosphere. They used sunlight energy to convert CO2 into O2 through photosynthesis. With time, enough oxygen accumulated, and Earth was able to support oxygen-breathing organisms on its surface.
The most primitive hominid remains aren’t older than 2 Ma. Primitive hominid remains formed no more than 3 to 5 Ma.
Modern rational humans (Homo sapiens) developed ONLY about 0.5 Ma (500,000 years)
Draw a diagram showing the structure and composition of the Earth
Picture 1 in desktop
Compare and contrast the stratification of the Earth as compared to other terrestrial plants
Earth’s stratification is similar as it has:
a) Lithosphere: stratified solid material
b) Atmosphere: gaseous envelope
Earth’s differs from other planets stems by:
a) Hydrosphere: water body, that brought about many other important differences
b) Biosphere: the aggregate of living things which interact strongly with other Earth systems
What are the major sybsytems of the dynamic Earth System and cycles?
Hydrosphere, biosphere, lithosphere, atmosphere and their interaction is powered by Earth’s mantle and solar energy. Rock cycle, water cycle, carbon cycle and tectonic cycles reflect a very dynamic earth.
