Flashcards in Midterm Study Guide Deck (27)
Why is Learning about Geology Important?
-Will provide students with a greater appreciation and understanding of the natural features that shape the earth
-Could Save your life, many geologic processes such as landslides, volcanic eruptions may pose significant hazards example: Oso WA and Mt. Pinatubo, Phillipines
-Will provide students with a greater with a greater appreciation and understanding of the natural processes that shape the earth
- Helps us plan our cities and design our structures Example Anchorage, Alaska after 1964 earthquake
How do we learn from our mistakes?
-Hanshin Expressway, Kobe Japan following the earthquake of 1995
-Even the best engineering standards are subject to failure until tested by mother nature. Improvements often follow failure
To understand Geology and the processes that shape the earth students need to do what?
Adjust their perspective of time.
When do human history and generational changes occur?
-They occur over decadal to millennial time scales, while geologic processes and the formation of the earth extend over millions to billions of years
What should one do to fully understand geology and earth's processes?
-one must take a system’s approach and understand that the components of Earth’s natural systems are often intrinsically linked or integrated
-Example Bristlecone Pine growing in the dolomitic soils in California and Nevada
What do Geologic factors such as lithology plan an important role in
-They play a role in soil nutrient availability and will consequently influence the vegetation distribution on a given landscape, as well as the climatic system.
What type of a science is Geology?
-Geology is an Integrated Science
What happened at Whidbey Island in WA
-Land Slide on March 27, 2013 luckily no lives were lost
How and When did the Earth and Solar System Form?
-The Nebular Hypothesis
What are the five steps of the Nebular Hypothesis?
a. Supernova and formation of primordial dust cloud
b. Condensation of Primordial dust. Forms disk shaped nubular cloud rotating counter clockwise
c. Proto sun and planets begin to form
d. Accretion of planetesimals and differentiation of planets and moons (4.6 billion years ago)
e. Existing Solar system takes shape
What are Four pieces of evidence to support the nubular hypothesis?
a. Planets and moons revolve in a counter-clockwise direction (not random)
b. Almost all planets and moons rotate on their axis in a counter-clockwise direction
c. Planetary orbits are aligned along the sun's equatorial plane (not randomly organized)
d. Observations from Hubble telescope and radio astronomy indicate that other planetary systems are forming from condensed nubular dust
What are Terrestrial Planets
They are planets that are close to the sun, dense, small rocky (silicate minerals, metallic cores_
What are Jovian Planets?
They are planets that are far from the sun, low density, large, gaseous (hydrogen, methane)
Can you explain why the earth and terrestrial planets have so little molecular hydrogen comprising their respective atmospheres; yet the primoridal dust cloud was mostly comprised of hydrogen gas?
The terrestrial planets are closer to the sun and the hydrogen gas is hotter, less dense, and lost to space
What is the Differentiated Earth?
1. Iron-Nickel core
(Outer Core liquid)
(Inner Core solid)
2. Fe-Mg Silicate Mantle
3. Fe-Mg Silicate Crust
(Ocean and continental)
How is the Earth compositionally zoned?
Alone a density gradient
How did the earth become compositionally zoned?
NEED TO UNDERSTAND THIS SEQUENCE OF EVOLUTIONARY EVENTS FOR MIDTERM
1. Accretion of Planetesimals.
2. Initial heating due kinetic energy of colliding planetesimals and compressional heating.
3. Additional heating from radioactive decay
4. Iron catastrophe (melting temperature of iron reached and dense iron-nickel sink to the core and lighter materials are displaced outwards (including silicate rock of mantle and crust, ocean waters and atmospheric gases.
5. Earth become compositionally zoned based on density (densest iron-nickel in core-least dense materials comprise the atmosphere).
6. Convective overturn in asthenosphere, mantle and outer core sill occur today
Why did the earth heat up and then rapidly cool during the differentiation process?
At first the solid earth slowly lost heat by conduction and by convection when it became molten
Which heat transfer process is more efficient (Conduction versus convection)?
Why does the earth possess little evidence of its early accretion history?
(Not sure how reliable but...) Weathering, plate tectonics, vegetation Only the crust and uppermost mantle can be directly observed. Molecular H and He escape to space and that oxygenation of the atmosphere occurred later following evolution of marine algae and plants that use photosynthesis to convert CO2 to O2 as a part of their life processes
When did the oceans and atmosphere form?
-It formed during the differentiation process
Explain the diagram on slide 10 on the second powerpoint
-Emissions from degassing of the Earth during its differentiation.
-Note that molecular H and He escape to space and that oxygenation of the atmosphere occurred later following evolution of marine algae and plants that use photosynthesis to convert CO2 to O2 as a part of their life processes.
What evidence do scientists use to support the above inferred compositional zonation?
Continental drift, fossils matching on two different continents, matching boundaries, and continents fitting together like puzzle pieces.
What are the three density properties of the earth?
1. The earth has an average density of 5.5gm/cm. The average density of the earth can be inferred based on gravitational properties of the earth and its effect on known masses such as orbiting (satellites).
2. The earth's crust has a density between 2.6 and 3.0gm/cm (directly measured).
3. The density of the uppermost mantle is 3.0 and 3.3 gm/cm (directly measured)
Based on the density properties of the earth, what can you infer about the density of the lower mantle and the earth's core?
The presence of the Earth’s magnetic field provides evidence that the Earth likely possesses a metallic core and that a component of this core must be liquid and convecting around the solid metallic portion of the core
What is evidence of seismic waves?
-Compression (P-waves) waves. Propagate through all phases of matter.
-Shear (S-waves) waves. Only propagate through solid phases of matter