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Geo 101 > Study guide quiz 1 > Flashcards

Study guide quiz 1 Flashcards

1
Q

Define scientific method

A

a sequence of steps for systematically analyzing scientific problems in a way that leads to verifiable results

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2
Q

Define scientific model

A

a precise representation of how a natural process operates or how a natural system behaves (HIGHEST level of confidence)

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3
Q

What is the principal of uniformitarianism and how is it applied by geologists?

A

“The present is key to the past”: Processes that act on the Earth today acted on the Earth in the geologic past

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4
Q

Understand the nebular hypothesis and how it applies to the formation of our solar system

A

Nebula: an area of space dominated by “dust”
• A nebula starts to collapse under its own gravity, stars form in the center
• The collapse of the nebula causes the nebula to spin faster
• As the nebula spins faster, it flattens into a disk
• The dust starts to clump up into larger pieces “planetesimals”

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5
Q

How did the Earth’s moon form? Why is the Earth’s orbital plane tilted?

A

Sometime during stages of accretion, a Mars-sized body impacted earth resulting in:
• Debris ejected into space forming our moon
• Speed up of Earth’s rotation
• Tilting of Earth’s orbital plane to 23 degrees

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6
Q

How does density change in Earth’s depth? What are the zones? How do the zones make up the tectonic plates? Which zones are strong/weak?

A

Crust: Continental and Oceanic (oceanic is more dense)
Forms the outermost rigid layer of the lithosphere distinguished by composition
Lithosphere: forms the strong outer shell and includes the crust and part of upper mantle
Asthenosphere: forms a moldable solidi and is the lower part of the upper mantle
Deep mantle: solid but hotter, contains most volume of Earth
Outer core: liquid
Inner core: solid

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7
Q

How old is the Earth?

A

About 4.5 billion years old

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8
Q

How did Earth’s continents, atmosphere and oceans form?

A

Continents: formed from the lighter molten materials rising to the surface due to differentiation and solidified as it cools
Oceans and Atmosphere: (2 hypothesis)
• Resulted from impact of volatile-rich matter impacting Earth from space early after it was formed such as comets
• Resulted from volatile tied up in planetesimals which formed the Earth. Volatiles released later by volcanism

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9
Q

Did Mars undergo the same processes that occurred on Earth?

A

Mostly Volcanism

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10
Q

The Earth has an external and internal heat engine. Why are they important? Where did the heat energy originate that powers the internal and external heat engines?

A
  • external heat engine: solar energy from the sun
  • internal heat engine: powered by heat energy trapped during planetesimal bombardment and heat generated by radioactive element decay deep within the Earth
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11
Q

What is the theory of plate tectonics? What is the driving force behind plate tectonics?

A

Theory: Outer portion of the Earth is lithosphere that is not a continuous shell but is broken in units called plates (about 12 large ones)
• These plates move (a few cm a year); plates ride on the asthenosphere which is also in motion
• Most geologic activity (earthquakes and volcanoes) concentrated near plate boundaries
Forces
• Ridge-push: bulging of the continent due to mantle upwelling gives rise to ridge push which initiates rifting (divergent)
• Slab-pull: by cold crust as it sinks into the mantle at a convergent boundary as the subducting slab descends it induces mantle circulation pulling the plate towards the trench (convergent)
Recycling goes down a few hundred km
All are part of convection process in the mantle

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12
Q

What is the continental drift hypothesis? What evidence did he use as support? Why was it not elevated to a theory? What is Pangea and when did it form?

A
  • Proposes that the continents are not in a fixed position but are instead continuously moving
  • Wegener used the following as evidence: continents seem to fit together, climate belts, fossils of animals that couldn’t have traveled across the ocean
  • Not elevated to a theory because Wegener did not have a mechanism to describe why this was occurring
  • Pangea was the super continent that the continents were previously arranged in before they split apart
  • Pangea was formed about 270 million years ago
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13
Q

What evidence was found that supports sea floor spreading? What is magnetic stripping? How and where does it form?

A
  • The seafloor becomes increasingly younger as the mid-ocean ridge is approached; the sea floor in general is younger than the continental crust
  • Magnetic stripping is the presence of parallel bands on the ocean seafloor of reversing magnetism; occurs due to the periodic reversal of Earth’s magnetic polarity in the magma
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14
Q

What is the “ring of fire” and what relevance does it have to plate tectonics?

A
  • The Ring of Fire is an arc in the Pacific Ocean along plate boundaries where a large amount of earthquakes and volcanic activity occur
  • This formed because of the convergent boundaries where oceanic crust subducts under the continental crust forming volcanoes
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15
Q

What type of plate boundary do earthquakes occur at? What type of plate boundary do volcanoes occur at?

A

Volcanoes occur at hotspots and convergent boundaries

Earthquakes occur at all plate boundaries

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16
Q

What are the 3 main types of plate boundaries and the subtypes of each? What are the plate motions relative to each other? What are the stresses located at each? What are the features associated with each?

A

• Divergent (mid-atlantic ridge, Iceland, sea of cortez)
Plate motions: moving away from each other by rifting/generating new crust
Stress: tension
Features: mid-ocean ridge, rift
• Convergent
Subtypes: continental-continental (no volcanoes, Appalachians, Himalayas) oceanic-oceanic (Japan, Phillipenes, Aleutian), continental-oceanic (Cascades, Andes)
Plate motions: moving towards each other
Stress: compression
Features: mountains, volcanoes, islands
• Transform
Examples: San Andreas
Plate motions: plates slide pass one another
Stress: Shear
Features: faults

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17
Q

What causes the plates to move?

A
  • Ridge-push: bulging of the continent due to mantle upwelling gives rise to ridge push (gravity driven mechanism) and initiates rifting
  • Slab-pull: by cold crust as it sinks into the mantle at a convergent boundary as the subjecting slab descends it induces mantle circulation pulling the plate towards the trench
  • Convection currents in the magma are the underlying reason
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18
Q

Why is there such a big difference between the age of the oceanic crust (about 200 my) and the continental crust (about 4 by)

A

• Oceanic crust is continuously being generated at divergent boundaries and then recycled back into the Earth at convergent boundaries where it subducts beneath less dense continental crust

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19
Q

What determines which plate will subduct? What is decompression melting and where does this occur? What type of crust will form there?

A
  • The more dense plate will subduct
  • Decompression melting is the upward movement of mantle to an area of lower pressure which enables it to melt
  • Occurs at divergent boundaries and generates oceanic crust
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20
Q

What is flux melting and where does it occur? What type of crust is destroyed? Is any new crust created? How deep are the plates recycled to?

A
  • Flux melting occurs when oceanic crust subduct under continental crust; the melting is sped up by the water from the ocean and magma rises through the crust to form volcanoes
  • Some new crust is created through accretion and magma flow from volcanoes
  • Plates are recycles up to a few 100 km deep
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21
Q

Where would you find “black smokers” and what plate boundary are they associated with?

A

They are located at divergent boundaries very deep in the ocean. Special shellfish and tube worms live there.

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22
Q

What are hot spots? Where would you find them? Do they create or destroy oceanic or continental crust? What feature/landform do you find above them?

A
  • They are a stationary, surface expression of volcanic activity
  • Result of a thermal plate, a localized source of rising heat energy from the mantle-core boundary
  • Examples are Yellowstone and Hawaii
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23
Q

How to tell the plate movement of hot spots?

A

Young to Old (from Big Island to Kawaii)

24
Q

What is the fate of California?

A
  • LA will slide up to meet SF and will continue to slide up and be an island
  • Will not fall into the ocean or will break off after a major earthquake
25
Q

What is a mineral?

A
  • naturally occurring
  • inorganic- no organic carbon (not a plant or animal)
  • crystalline solid- atoms are arranged in a particular structure (ex a cube)
  • specific chemical compound- contains particular elements in a set ratio
26
Q

What is an isotope? How can they be used in geology

A
  • the number of neutrons changes
  • ex: all carbon atoms have 6 protons (atomic number) + 6 neutrons =12
  • carbon 13 (7 neutrons) and carbon 14 (8 neutrons) are isotopes of carbon
27
Q

What is chemical bonding? Describe differences between ionic and covalent bonding?

A

Minerals form when atoms transfer or share electrons to fill their shells

Ionic bonding
• transfer of electrons
• form when shells are nearly empty or nearly full
• weak bond

covalent bonding
• sharing of electrons
• form when shells are about half full
• strong bond

28
Q

How do minerals form? What determines the location they will be formed at? What conditions are they formed under?

A
  • minerals form from chemical reactions between elements; crystallization- the growth of a solid from a gas or liquid whose constituents come together in the proper chemical proportions and crystalline arrangement
  • conditions under which they form: lower the temperature of a liquid below freezing point, liquids evaporate from a solution forming a supersaturated solution and results in precipitate; when atoms and ions in a solid become mobile and arrange themselves at high temp (>250 celcius)
29
Q

What are polymorphs?

A
  • same composition but different crystal structure

* ex: diamond and graphite

30
Q

What are the three main rock types and what processes (melting; weathering; metamorphism) cause them to form?

A
  1. Igneous- solidification of molten rock or melt (found by volcanoes)
  2. Sedimentary- cementing together fragments of preexisting rocks or by precipitation of mineral crystals out of water solutions at or near Earth’s surface
  3. Metamorphic- rocks change character in the solid state as a response to a change in pressure and temperature conditions (does not require melting)
31
Q

What is the most abundant rock type in the Earth’s crust? What is the most abundant rock type we find on the land surface?

A
  • Igneous is most abundant in Earth’s crust

* Sedimentary is most common on land surface

32
Q

Understand the rock cycle in a plate tectonic setting, in the context of identifying where any particular rock type is likely to be found/deposited. Also, understand the rock cycle in context of how one rock type can be changed to another.

A
  • Igneous rocks: convergent, divergent, hotspots (wherever there is melting)
  • Sedimentary: convergent (mountain building)
  • Metamorphic: convergent boundaries
33
Q

How are igneous rock formed? What are the two types of igneous rock? How does the location where they cool affect the speed of cooling and there crystal size?

A
  • Formed from the solidifications of molten rock
  • Two types
  • Intrusive: cool slowly underground and have large crystals
  • Extrusive: cool rapidly on the surface and have small crystals
34
Q

Understand and be able to use (or recognize in slides) the following terms: plutonic, volcanic, intrusive, extrusive, aphanitic, phaneritic, porphyritic, pegmatitic, glassy, vesicular, pyroclastic. What does each texture indicate about the rate of cooling?

A
  • Aphanitic: very small crystals (fine) extrusive
  • Porphyritic: two stages of cooling; one slow deep in the surface and one fast above the surface
  • Coarse: phaneritic intrusive
  • Pegmatitic: extremely coarse
35
Q

Where are magmas generated? What makes magma? How do rocks melt (3 ways)?
Give an example of the plate tectonic setting that corresponds to each way. What type of magma is produced in Hawaii (low viscosity, high temp, mafic)? Yellowstone? (intermediate/felsic) Cascades? (felsic/intermediate) Andes? (felsic/intermediate)

A
  • Magmas are generated at: divergent, convergent (oceanic/continental), hot spots, and continental calderas
  • The composition of the magma is a reflection of where the melting took place and what type of lithosphere is involved
  • Rocks melt by:
  • Raising the temperature “heat-transfer melting”
  • Lower pressure “decompression melting”
  • Add volatiles: H2O, CO2, etc “reflux melting” which lowers melting temperature
36
Q

Igneous rocks are classified based on there silica composition. What are the four composition groups? What is there relative melting temperature order for the compositional groups? How do Fe –Mg and Si –Na-K vary in the groups? What minerals would you expect to see or not see in rocks created from Mafic and Felsic compositions magma?

A
  • Ultramafic: lowest silica, dark colored (green) highest melting temp (melts last) highest iron
  • Mafic: low silica, dark colored (green/brown/black)
  • Intermediate: intermediate silica, intermediate color (grey, grey/green)
  • Felsic: high silica, light color (white, light grey, pink) lowest melting temp (melts first) lowest iron
37
Q

How does viscosity vary among the compositional groups? How is this related to the magma temperature and magma composition?

A

• mafic: low silica, high temperature- low viscosity
-Intermediate: intermediate temp = high viscosity
• Felsic: high silica, low temperature- very high viscosity

38
Q

From magma to igneous rock: What process is involved? What is fractional crystallization? Why does this change the composition of the remaining magma?

A
  • The magma cools, solidifies, and then forms silicate minerals
  • Fractional crystallization: high temperature minerals crystallize first; these are the mafic minerals
39
Q

Where do ophiolites form at? Are gabbro and peridiotite found there?
Be able to identify the different forms of intrusions (sill, dike, batholith, vein (figure 4.10, 4.11) for slides and multiple choice questions. Where do they form? How does magma make its way to the surface?

A
  • Sill: parallel to bedding, most are horizontal
  • Dike: cuts across sedimentary rock units vertically
  • Batholith: large igneous rock body at surface of the earth greater than 100 km2
40
Q

Muana Loa

A

Shield volcano

low viscosity, high temperature, mafic, low silica, effusive eruption, hot spot

41
Q

Mt. Rainer

A

Strato volcano

high viscosity, low temperature, felsic/intermediate, high silica, pyroclastic, convergent

42
Q

Columbia River

A

Flood basalts

low viscosity, high temperature, low silica, pyroclastic

43
Q

Crater Lake

A

high viscosity, low temp, felsic, high silica, explosive (don’t need to know plate tectonic setting)

44
Q

What are the two types of lava textures

A

Aa texture: sharp material/blocky

Pahoehoe texture: ropey/smooth

45
Q

Pillow Basalts

A

form when lava flows into a body of water and the outside shell crystallizes

46
Q

Why do volcanoes erupt?

A

The pressure/gasses are dissolved in the magma and are trying to escape as they reach the surface.

47
Q

What is an effusive eruption?

A

Gentle eruptions
Lava dominates
Magma generally low in silica- high temperature
Low viscosity
Occurs commonly at divergent boundaries and hot spots

Ex: Flood basalts

48
Q

Define pyroclastic

A

Violent eruption
Lava high in silica- lower temperature
High viscosity
Occurs commonly at convergent boundaries and hot spots
Composite volcanoes (cinder cones, calderas)
Ex: Mt. St. Helens

49
Q

What is a central vent vs fissure?

A

A central vent is when the volcano explodes from the top and fissures are like a crack along the ground that erupts

50
Q

What are flood basalts?

A

primarily from fissure eruptions
Mafic lava
Generally flat layers

Ex: Colombia flood basalts

51
Q

What are shield volcanoes?

A

Primarily vent eruption
May also have fissure eruptions
Primarily mafic laca
Gently sloping, broad

Forms because the lava is not very viscous so the lava was able to flow to large distances

52
Q

What are cinder cones?

A 
Vent eruptions 
Mafic lava and pyroclastic rocks 
Steep slopes 
Not very big 
Usually found near other major volcanoes
53
Q

What are spatter cones?

A

Vent eruptions
Primarily mafic lava
Steep slope
Small size

54
Q

What are strato volcanoes? (composite volcano)

A

Vent eruption
Steep slopes
Composed of alternating pyroclastic layers and felsic to intermediate lava flows
Concave up profile

Rainer, St. Helens, etc.

55
Q

What are calderas?

A

dsadasd

Geo 101 (6 decks)

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