Midterm Topics Flashcards
How old is the universe?
Approximately 13.7 billion years old
What is the difference between the heliocentric and geocentric models?
Geocentric model puts the Earth at the center of the solar system with the other planets and Sun revolving around it
Heliocentric model puts Sun at the center of the solar system with the Earth and the other planets revolving around it
Retrograde motion of Mars helped spur the transition between two models
What evidence do we have that the universe is expanding?
Due to the Doppler Effect, we know that wavelengths of objects moving towards us will be shorter and those moving farther will be longer.
Since light from distant galaxies is red-shifted (longer wavelength), we know they are moving farther away from us, and thus, the universe is expanding
What is parallax?
Parallax is the apparent shift in position of an object caused by viewing from different places. Stellar parallax (caused by Earth’s different locations during solar orbit) lets us estimate distances to planets and stars
How do stars work?
Stars derive their energy through nuclear fusion. They start with hydrogen and continue fusing to get continuously heavier elements.
How was our solar system formed?
Formed through a nebula
As the nebula contracts due to gravity, it flattens
Star is born in the center and the disk becomes planets
Hydrogen and helium remain gases but others can condense into solids
Seeds collide and combine, and their gravity attracts other seeds
Order of the Planets
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Which planets are rocky? Gaseous?
The inner planets (Mercury to Mars) are rocky. The outer planets (Jupiter to Neptune) are gaseous.
Inner planets are rocky because warm temperatures only allow rocks and metals to be solid near the Sun.
Outer planets are gaseous as the colder temperature allows gases to condense and accrete near planets.
Is Pluto a planet?
Pluto is not a planet as it doesn’t have the same orbital plane as the other planets and is rocky; rocky planets are usually close to the Sun
How old is Earth?
Around 4.5 billion years old. Oldest meteorites on Earth are 4.5 billion years old and oldest minerals are 4.2 billion years old.
What is the difference between volatile and refractory elements?
Volatile elements have a low boiling point and condense at low temperatures
- Examples include light elements (H, He) and gases at room temperature (O, N, Ne, Air)
- Formed gas giants
Refractory elements have a high boiling point and remain solid even at high temperatures
- Heavier elements such as Ca, Al, Fe, Mg, Ni, Si (around 1000-1500 C)
- Form rocky planets and the asteroid belt
How did the exploration of the ocean begin in ancient times? Contrast that with more modern
oceanography.
Ocean exploration in ancient times began with trade. People went on the ocean to mainly trade or voyage for new land. Modern oceanography began with the HMS Challenger, the first vessel to set out on a purely scientific expedition.
Why were clocks so important in ocean exploration?
Clocks were important as they were the key to determining longitude. Since longitude was based on the Greenwich Meridian, the Greenwich time of your local noon can tell your longitude.
Clocks were a way to track what Greenwich time was and therefore to track the longitude
What did sailors use to determine location in regards to longitude? Latitude?
To determine latitude, sailors measured the positions of stars, from declination to the Pole Star.
To determine longitude, sailors used Greenwich time and it’s discrepancy from their local noon
List a few pieces of equipment used by current oceanographers.
ROVs
Clocks
Satellites
- TOPEX/Poseidon: Covers 95% of ice-free ocean every 10 days
- Jason-1: Monitors ocean/atmosphere climate interactions
- AQUA: Collects water-cycle information
What are the 4 main internal parts of the earth? Are they solid or liquid? Bendable or not? Rank in
order of density.
4 main parts of the Earth are the crust, mantle, outer core, and inner core
Crust and mantle are rocky/solid, outer core is liquid, inner core is solid
Crust and inner core are not bendable; mantle and outer core are
Increasing Density: Crust, Mantle, Outer Core, Inner Core
What is the difference between oceanic and continental crust?
Oceanic crust is much thinner and is denser than continental crust; primarily composed of basalt
Continental crust is not as dense as oceanic crust and is mainly composed of granite
What have seismic waves told us about Earth? What is the difference between P waves and S
waves?
P Waves
- Primary waves
- Faster than S waves
- Compressional
- Can travel through solids, liquids, and gases
S Waves
- Secondary waves
- Slower than P waves
- Shear
- Can only travel through solids (no restoring force in other media)
Seismic waves tell us about Earth’s composition and the presence of the liquid outer core. S-waves can’t pass through the outer core and thus cast a shadow zone. P-waves cast differential shadow zones as they move/bend differently in a liquid, compared to the solid interior parts.
Is Earth like the rest of the Universe? Why? Why does Earth have a liquid ocean?
Earth is not like the rest of the universe as it is the only known planet with liquid water on the surface.
Earth has a liquid ocean because of the rapid accretion of cold/icy planetesimals in formation, outgassing of interior bringing H2O to the surface, and moderate distance from the sun allowing for water to remain liquid
What is the theory of continental drift and what evidence did Wegener use to support the theory?
Theory of continental drift states that continents move laterally across Earth, were joined as a supercontinent in the past, supercontinent had a superocean, and the supercontinent split apart 200 mya and pieces move today
Wegener used the evidence of the fit of the continents with each other, incomplete geologies of South Africa and Australia, and distribution of living organisms/fossils/paleoclimatic indicators
Why wasn’t the theory of continental drift originally accepted?
- Lack of suitable mechanism to move continents
- No way for continents to plow through the ocean floor
- Wegener was meteorologist, not a geophysicist
What is the seafloor spreading hypothesis?
- Convection cells of mantle cause mantle upswells under mid-ocean ridges
- Lithosphere with new crust is formed at mid-ocean ridges, then spreads laterally across seafloor
- Oceanic crust of lithosphere is dragged down at trenches and recycled into mantle
What lines of evidence backed up seafloor spreading?
- 1970s deep sea drilling showed that age of seafloor increases regularly with distance from ridge axis
- Sediment thickens with distance from ridge axis
- Polarity of magnetic materials in seafloor rocks alternates and then ends at a trench
What is the theory of plate tectonics?
- Earth’s surface consists of a small number of plates that correspond to the lithosphere
- Lithospheric plates move over Earth’s surface by riding on the asthenosphere, powered by movement in the mantle
- Plates interact with each other along 3 kinds of boundaries
- Plate interactions produce most of Earth’s tectonic activity
What evidence did scientists use to form the theory of plate tectonics?
- Global earthquake patterns occurring in a distinct manner
- Volcano hotspots
- Shape/fit of continents
- Fossil record across continents
Understand and be able to describe: a) what happens at each type of plate boundary b) if crust is
created or destroyed c) the geological features that occur at these locations d) where the boundary
occurs
Constructional Plate Boundaries:
- Plates move apart from one another
- Crust is created from magma upswells at mid-ocean ridges
- Mid-ocean ridges and rift valleys occur here
- Examples include mid-Atlantic ridge and East Africa Rift Valley
Destructional Plate Boundaries:
- Plates move towards each other
- Crust is destroyed as one plate subducts under the other
- Geological features that can occur are deep sea trenches and mountain ranges
- Examples include Himalayas, Andes, and where the Nazca plate subducts under the South American plate
Transform Plate Boundaries;
- Plates shear past one another
- Crust is neither made nor destroyed
- Transform faults occur as Earth is a sphere
- Example is San Andreas fault between Pacific and North American plates
What is a supercontinent?
A supercontinent is what occurs when all of Earth’s continents congregate into one large landmass
What is a hot spot?
Hot spots are point sources of magma that have remained fixed in one spot of the mantle for long time periods; mode of mantle upwelling
What are Large Igneous Provinces?
Large Igneous Provinces (LIPS) are large accumulations of igneous rocks, resulting from the large heads of mantle plumes
What are the global effects of LIPS?
- Raise sea level when erupting on sea floor
- Raise seawater temperature
- Raise atmospheric temperature
- Potentially could cause mass biotic extinctions
Why is there a bend in the Hawaiian-Emperor Seamount chain?
The bend is caused by change in direction of the Pacific plate, as this disturbed the linear motion of the hot spot that created the chain in the first place
What is the principle of uniformity?
Today’s geologic features were formed in the past by the same geologic processes
observed today.
How is the seafloor mapped? Is one method better or worse than the others?
- Echo Sounding
- Multi-Beam Systems
- Satellite Altimetry
Multi-beam systems seem to produce the most detailed images
Oceanic Ridge Formation
Formed where two plates are moving apart from each other (divergent boundary
Oceanic ridges are the places where new crust emerges
Hydrothermal Vent Formation
Magma near the seafloor heats up water under the seafloor. This causes it to be able to dissolve more metals. Once this water comes up and hits the colder surrounding water, the dissolved metals precipitate out, forming the vent around it over time.
Abyssal Plain Formation
Forms through accumulation of layers of sediment on the basaltic oceanic crust over time
Abyssal plains are flat, featureless expanses of sediment- covered ocean floor found on the periphery of all oceans.
Abyssal Hill Formation
Abyssal hills form when newly formed crust moves away from the center of a ridge, stretches, and cracks. Some blocks of the crust form valleys and others remain as hills.
Abyssal hills are small, sediment-covered extinct volcanoes or intrusions of once-molten rock, usually less than 200m high
Seamount Formation
Seamounts are volcanoes formed at or near mid-ocean ridges or at hot spots, and occur when magma forms an inactive volcano underwater
Guyot Formation
Guyots are flat-topped seamounts that once penetrated the water’s surface, and wave-action eroded their tops to become flat
Trench Formation
Trenches are deep depressions in the seafloor
- They occur when a convergent oceanic plate is subducted beneath another oceanic plate
Island Arc Formation
Island arcs are a result of an oceanic plate being subducted under another oceanic plate and are composed of andesite Ex. Japan/Aleutian
Island Chain Formation
Island chains form due to hotspots and are composed of basalt Ex. Hawaiian
Continental Shelf Formation
Shelves are wider at passive margins as they are mainly formed by seafloor spreading. Shelves are narrower at active margins as occurring subduction narrows them.
Continental Slope Formation
Continental slope depth is also determined by presence of active or passive margins, like shelf formation
In what location would you find an active continental margin? What about a passive continental
margin? What are the differences between these two margins?
- Active margins occur more frequently around the Pacific and near the edge of convergent/transform boundaries
- Passive margins occur more frequently around the Atlantic and near the edge of divergent boundaries
- Active margins have more earthquake activity and narrower continental shelves than passive margins
There are 3 main types of rocks. How is each type formed?
Igneous Rocks: Formed from magma above or below Earth’s surface
- Intrusive rocks formed underground, for a longer time, from magma, and have larger crystals
- Extrusive rocks formed above ground, quickly, have smaller crystals, and from lava
Sedimentary Rocks: Formed by sediment compaction, sediment cementation, or direct formation of crystals during evaporation of water
Metamorphic Rocks: Formed from previous rocks changed by heat, pressure, and/or hot solutions
