Test 2 Flashcards
What is the unit of energy in the metric system?
The Joule
What is the unit of power in the metric system?
The Watt
What is the unit of force in the metric system?
The Newton
How is the Permian extinction seen in the fossil record?
Sandstone, Land plants, and animal fossils.
At least 50% of all fish and invertebrate species disappear from fossil record after the Permian
How is the Cretaceous extinction seen in the fossil record?
What evidence do we have that a
large asteroid strike caused the extinction of the dinosaurs?
When the Cretaceous ended, the big marine reptiles had disappeared, the flying reptiles, the dinosaurs, the Russified clams, and many species of fish-not to mention the total elimination or severe reduction of countless smaller species from the sea.
It is seen in the K-T boundary- a layer of sediments/soil deposits that divides the cretaceous and tertiary periods.
Iridium likely formed the asteroid, iridium content 100 times the natural abundance in crust. The K-T boundary is a layer of sediments that divides the cretaceous and tertiary periods and is the after effects of a massive asteroidal impact.
What is an index fossil and what makes a species a good index fossil?
Fossils of creatures that appeared suddenly, had evolved quickly, and became abundant and geographically widespread and then died out abruptly. They are studied in groups in order to figure out the relative ages of rock through the relating of successive strata to whole collections of creatures whose fossils were contained therein.
What did the appearance of hard body parts mean for the fossil record?
Fossils from the beginning of the Phanerozoic Eon are easier to find than fossils from the Proterozoic Eon because many organisms started to have skeletons, shells, rigid coats and other hard parts in the Phanerozoic but not in the Protozeroic.
Increases fossil record size
What are the major components of the interior of the Earth?
Inner Core: mostly iron and some nickel.
Outer Core: mostly iron and some nickel.
Mantle: Rock-silicates.
Crust (16 tectonic plates) : Rock
How can we measure the mass of the Earth? (=what do we need to know?)
F=G(M1)(M2)/d^2 F: Force of Gravity M1: Mass of the 1st object M2:Mass of 2nd object (mass of the earth) d: distance between their centers G: "Gravitational force constant"
Using the force of gravity and acceleration of falling objects on earth.
How does the density of the Earth show that it is not rock all the way through?
The density of the earth is 5.4 g/cc. This is more dense than water and air and between rock and iron.
Earth cannot be all rock because earthquakes create seismic waves that pass through the earth.
- S waves are shear waves that pass through solids but are reflected/absorbed by liquid (molten) regions.
- p waves are pressure waves that pass through both solid and molten regions.
Is the density of the Moon larger or smaller than the Earth? What does that tell us about the
composition of the Moon?
Smaller
The material that formed the Moon was mostly from Earth’s mantle (rock silicates). What makes Earth denser than the Moon is its iron core (which is really big, larger than the Moon!).
The Moon has about the same density as mantle rock.
The average composition of the lunar surface by weight is roughly 43 percent oxygen, 20 percent silicon, 19 percent magnesium, 10 percent iron, 3 percent calcium, 3 percent aluminum, 0.42 percent chromium, 0.18 percent titanium and 0.12 percent manganese.
What is differentiation and how does it explain the change in composition from crust to core?
When a hot body separates into heavier iron core and fluffier rock mantle.
The inside of the earth is hot, dense, as strongly differentiated into light silicates and heavy metals.
-heavier iron center and lighter matter outside
How does the study of earthquakes show that the Earth has a liquid outer core?
Earthquakes create seismic waves that pass through the earth
-s waves are shear waves that pass through solids and are reflected/absorbed by LIQUID MOLTEN REGIONS
-p-waves are pressure waves that pass through both solid and MOLTEN regions
What part of the interior of Earth is needed for the Earth to have a strong magnetic field?
liquid outer iron core
The flowing electrically conducting iron fluid sets up an electric dynamo, this generates a strong magnetic field that extends out into interplanetary space.
The magnetic field deflects solar wind (fast electrons and protons streaming away from the sun)
What does the magnetic field protect Earth from?
How has Mars suffered because it does not
have a strong magnetic field?
the sun is constantly spitting out fast electrons and protons (called solar wind). These particles are constantly streaming towards the Earth, and without the magnetic field, they would enter our atmosphere and could cause quite bit of damage to the atmosphere, life on the surface, and our electronic equipment. However, the Earth’s magnetic field deflects these particles, and funnels them into the north and south poles of the Earth, where the magnetic field lines enter and exit the Earth.
Mars has an atmosphere not protected by solar wind that is being stripped-it is thin, dry, and composed mostly of carbon dioxide
Why is the Earth still hot in its interior?
Why is that important for plate tectonics?
For the magnetic field?
- Residual heat of formation (started hot and hasn’t lost all heat yet)
- radioactive heating from potassium, thorium, and uranium
The 16 plates on top of the mantle move around driven by convection currents. Convection currents are a result of the asthenosphere (part of the mantle) being heated from below.
The earth’s magnetic field is generated by convection currents in the molten outer core
-the flowing electrically conducting iron fluid sets up an electric dynamo, this generates a strong magnetic field that extends out into interplanetary space.
What is the greenhouse effect?
The greenhouse effect occurs when the warm ground radiates infrared photons. Infrared photons are observed by molecules of H2o, Co2, CH4 and others, the absorbed energy heats the atmosphere. This makes the earth about 33 degrees celsius warmer than it would be if it had no atmosphere.
What is the definition of the equilibrium temperature of a planet?
If the energy absorbed by a planet is equal to the energy radiated by a planet, then the planet has reached its equilibrium temperature.
Why can a planet have a different temperature than its equilibrium temperature?
Greenhouse effect. for planets with “greenhouse” gases (molecules which absorb in the IR) in their atmospheres, a large percentage of the IR radiation is “trapped” near the surface which heats the lower atmosphere and surface to much higher temperatures which in turn causes more IR radiation until the surface temperature reaches an equilibrium value such that the fraction of the IR radiation which does escape is equal to the radiation absorbed from the Sun
Has our atmosphere always had the same composition? If not, what processes have caused its
composition to change?
No,
- escape velocity
- greenhouse effect
- solar radiation and solar wind
