Ess 101 Exam 1 Questions With Correct
Detailed Answers .
nebular hypothesis - ANSWER- 1. supernova and formation of primordial dust
cloud
2. condensation of primordial dust forms disk shaped nebular cloud
rotating counter- clockwise.
3. proto sun and planets begin to form
4. accretion of planetesimals and differentiation of planets and moons (4-6
billion years ago).
5. existing solar system takes shape.
Evidence of nebular hypotheses - ANSWER- 1. Planets and moons
revolve in a counter-clockwise direction (not random)
2. almost all planets and moons rotate on their axis in a counter-clockwise
direction.
3. planetary orbits are aligned along the suns equatorial plane (not randomly
organized)
4. observations from Hubble telescope and radio astronomy indicate
that other planetary systems are forming from condensed nebular
dust.
Terrestrial Planets - ANSWER- Close to the sun, dense, small/rocky, silicate
minerals, metallic cores
Twelve earths would fit across the diameter of Jupiter.
Jovian Planets - ANSWER- Far from the sun, low density, large, gaseous
(hydrogen, methane)
Why does the earth and terrestrial planets have so little molecular hydrogen
comprising their respective atmosphere, yet the primordial dust cloud was
mostly comprised of hydrogen gas? - ANSWER- Hydrogen gas and helium
gas escapes to space when put in our atmosphere.
Jupiter, saturn, and neptune maintain molecular hydrogen gas in the
atmosphere because they have high density.
Differentiated Earth - ANSWER- 1. Iron Nickel Core (outer core
liquid) (inner core solid)
2. Fe-Mg silicate mantle
3. Fe-Mg-Al Silicate Crust (Ocean and Continental)
4. Oceans
5. atmosphere
How is the earth compositionally zoned? - ANSWER- Along a density gradient
,How did the earth become compositionally zoned? - ANSWER- 1. Accretion of
planetesimals
2. initial heating due to kinetic energy of colliding planetesimals and
compressional heating.
3. additional heating from radioactive decay.
4. iron catastrophe: melting temp of iron reached and dense iron nickel sink
to core and lighter materials are displaced outwards (including silicate rock
of mantle and crust, ocean waters and atmospheric gases)
5. earth becomes compositionally zoned based on density (densest iron
nickel in core- least dense materials comprise the atmosphere) 500 mil yrs
after the initial accretion process.
6. convective overturn in asthenosphere, mantle and outer core still occur
today.
Why did the earth heat up and then rapidly cool during the differentiation
process? - ANSWER- When earth was solid-heat gain was greater than the
heat lost to space. This means that the internal temperature rises until it
exceeded the melting temp of oxygen and nitrogen until exceeded iron
nickel catastrophe. Earth is completely molten and then compositionally
zoned.
When earth was liquid- convection-hot gas rises , after it became molten, the
earth rapidly cooled off and solidified.
Why does earth possess little evidence of its early accretion history? -
ANSWER- Because of weathering, plate tectonics, moon has no atmosphere
and biosphere.
Emissions from degassing of the earth during its differentiation. - ANSWER-
h2o, co2, h2, he, n2
Where did molecular H and He escape to? - ANSWER- space
When did oxygenation of the atmosphere occur? - ANSWER- later following
evolution of marine algae and plants that use photosynthesis to convert co2
to o2 as a part of their life processes.
What layers of the earth can be directly observed? - ANSWER- crust and
uppermost mantle.
Evidence of initial composition of the solid earth based on meteorite studies.
There are two major classes of meteorites that dominate collected samples.
Carbon based meteorites are much rarer, but indicate that the prescursor of
life was present early on. - ANSWER- 1. Metallic meteorites (iron nickel
density 9.0-10 gm/cm3)
2. chondritic meteorites: Fe-Mg silicate, rocky, density is 3.0-3.3)
3. carbonaceous chondrites (rare)
What is earths average density? - ANSWER- 5.5 g/cm3
,How can average density of earth be inferred? - ANSWER- Based on
gravitational properties and its effect on known masses such as orbiting
satellites.
Density of earths crust? - ANSWER- 2.6-3 g/cm3
density of uppermost mantle? - ANSWER- 3.0-3.3 g/cm3
Based on the density information, what can you infer about the density of
the lower mantle and the earths core? - ANSWER- Density must be higher
than the average.
What does the presence of the Earth's magnetic field provide evidence for? -
ANSWER- Earth is likely to possess a metallic core and that a component of
this core must be liquid and convecting around the solid metallic portion of
the core.
Seismic waves - ANSWER- s and p waves
P waves - ANSWER- Compression waves, velocity: 6-7 km/sec within
lithosphere, propagate through all phases of matter.
S waves - ANSWER- Shear waves, 3-4 km/sec, only propagate through solid
phases of matter, not liquids or gases, require rigid substance (solid) to
propagate.
Seismic waves refract because - ANSWER- because of velocity changes
related to density changes within the earth. seismic wave accelerate with
increasing density.
P wave shadow zone - ANSWER- bagel shaped, exist between 105-140
degrees from the epicenter due to refraction at outer core mantle boundary.
no p or s waves.
s wave shadow zone - ANSWER- only one large shadow zone at an angle
greater than 105 degrees of the epicenter. due to refraction at outer core
mantle boundary and because s waves are absorbed by the liquid outer
core.
When does seismic wave velocity decrease? - ANSWER- at depth of 100-
350 km and at the mantle-core boundary. (low velocity zone)
When are s waves absorbed? - ANSWER- only at the mantle-core boundary.
What does the s wave being absorbed only at the mantle core boundary tell
you about the physical property of the upper mantle? - ANSWER- It is
partially melted.
lithosphere - ANSWER- continental, ocean crust, and uppermost solid mantle
, Asthenosphere - ANSWER- upper ductile mantle
Detailed Answers .
nebular hypothesis - ANSWER- 1. supernova and formation of primordial dust
cloud
2. condensation of primordial dust forms disk shaped nebular cloud
rotating counter- clockwise.
3. proto sun and planets begin to form
4. accretion of planetesimals and differentiation of planets and moons (4-6
billion years ago).
5. existing solar system takes shape.
Evidence of nebular hypotheses - ANSWER- 1. Planets and moons
revolve in a counter-clockwise direction (not random)
2. almost all planets and moons rotate on their axis in a counter-clockwise
direction.
3. planetary orbits are aligned along the suns equatorial plane (not randomly
organized)
4. observations from Hubble telescope and radio astronomy indicate
that other planetary systems are forming from condensed nebular
dust.
Terrestrial Planets - ANSWER- Close to the sun, dense, small/rocky, silicate
minerals, metallic cores
Twelve earths would fit across the diameter of Jupiter.
Jovian Planets - ANSWER- Far from the sun, low density, large, gaseous
(hydrogen, methane)
Why does the earth and terrestrial planets have so little molecular hydrogen
comprising their respective atmosphere, yet the primordial dust cloud was
mostly comprised of hydrogen gas? - ANSWER- Hydrogen gas and helium
gas escapes to space when put in our atmosphere.
Jupiter, saturn, and neptune maintain molecular hydrogen gas in the
atmosphere because they have high density.
Differentiated Earth - ANSWER- 1. Iron Nickel Core (outer core
liquid) (inner core solid)
2. Fe-Mg silicate mantle
3. Fe-Mg-Al Silicate Crust (Ocean and Continental)
4. Oceans
5. atmosphere
How is the earth compositionally zoned? - ANSWER- Along a density gradient
,How did the earth become compositionally zoned? - ANSWER- 1. Accretion of
planetesimals
2. initial heating due to kinetic energy of colliding planetesimals and
compressional heating.
3. additional heating from radioactive decay.
4. iron catastrophe: melting temp of iron reached and dense iron nickel sink
to core and lighter materials are displaced outwards (including silicate rock
of mantle and crust, ocean waters and atmospheric gases)
5. earth becomes compositionally zoned based on density (densest iron
nickel in core- least dense materials comprise the atmosphere) 500 mil yrs
after the initial accretion process.
6. convective overturn in asthenosphere, mantle and outer core still occur
today.
Why did the earth heat up and then rapidly cool during the differentiation
process? - ANSWER- When earth was solid-heat gain was greater than the
heat lost to space. This means that the internal temperature rises until it
exceeded the melting temp of oxygen and nitrogen until exceeded iron
nickel catastrophe. Earth is completely molten and then compositionally
zoned.
When earth was liquid- convection-hot gas rises , after it became molten, the
earth rapidly cooled off and solidified.
Why does earth possess little evidence of its early accretion history? -
ANSWER- Because of weathering, plate tectonics, moon has no atmosphere
and biosphere.
Emissions from degassing of the earth during its differentiation. - ANSWER-
h2o, co2, h2, he, n2
Where did molecular H and He escape to? - ANSWER- space
When did oxygenation of the atmosphere occur? - ANSWER- later following
evolution of marine algae and plants that use photosynthesis to convert co2
to o2 as a part of their life processes.
What layers of the earth can be directly observed? - ANSWER- crust and
uppermost mantle.
Evidence of initial composition of the solid earth based on meteorite studies.
There are two major classes of meteorites that dominate collected samples.
Carbon based meteorites are much rarer, but indicate that the prescursor of
life was present early on. - ANSWER- 1. Metallic meteorites (iron nickel
density 9.0-10 gm/cm3)
2. chondritic meteorites: Fe-Mg silicate, rocky, density is 3.0-3.3)
3. carbonaceous chondrites (rare)
What is earths average density? - ANSWER- 5.5 g/cm3
,How can average density of earth be inferred? - ANSWER- Based on
gravitational properties and its effect on known masses such as orbiting
satellites.
Density of earths crust? - ANSWER- 2.6-3 g/cm3
density of uppermost mantle? - ANSWER- 3.0-3.3 g/cm3
Based on the density information, what can you infer about the density of
the lower mantle and the earths core? - ANSWER- Density must be higher
than the average.
What does the presence of the Earth's magnetic field provide evidence for? -
ANSWER- Earth is likely to possess a metallic core and that a component of
this core must be liquid and convecting around the solid metallic portion of
the core.
Seismic waves - ANSWER- s and p waves
P waves - ANSWER- Compression waves, velocity: 6-7 km/sec within
lithosphere, propagate through all phases of matter.
S waves - ANSWER- Shear waves, 3-4 km/sec, only propagate through solid
phases of matter, not liquids or gases, require rigid substance (solid) to
propagate.
Seismic waves refract because - ANSWER- because of velocity changes
related to density changes within the earth. seismic wave accelerate with
increasing density.
P wave shadow zone - ANSWER- bagel shaped, exist between 105-140
degrees from the epicenter due to refraction at outer core mantle boundary.
no p or s waves.
s wave shadow zone - ANSWER- only one large shadow zone at an angle
greater than 105 degrees of the epicenter. due to refraction at outer core
mantle boundary and because s waves are absorbed by the liquid outer
core.
When does seismic wave velocity decrease? - ANSWER- at depth of 100-
350 km and at the mantle-core boundary. (low velocity zone)
When are s waves absorbed? - ANSWER- only at the mantle-core boundary.
What does the s wave being absorbed only at the mantle core boundary tell
you about the physical property of the upper mantle? - ANSWER- It is
partially melted.
lithosphere - ANSWER- continental, ocean crust, and uppermost solid mantle
, Asthenosphere - ANSWER- upper ductile mantle
