Exam I

Question 1

Difference between hypothesis, theory, and law

Answer 1

Hypothesis: development of an explanation that fits the data

Theory: a hypothesis that has survived repeated tests and is supported by evidence

Law: description of natural phenomenon or principle that holds true

Question 2

Overview of scientific method

Answer 2

observation, hypothesis, experiment, conclusion, maybe re-design hypothesis and repeat

Question 3

What is meant by “deep time”

Answer 3

the concept of geologic time that spans billions of years into the past

Question 4

What is catastrophism, and how does that differ from uniformitarianism and actualism

Answer 4

catastrophism: changes to earth’s surface only happen during violent, sudden events
uniformitarianism: geologic processes are uniform through time
actualism: processes are the same but the rates may differ over time

Question 5

What are earth’s four systems, and how do they interact with each other?

Answer 5

Hydrosphere
Biosphere
Atmosphere
Lithosphere

Question 6

What role does the exosphere play?

Answer 6

deals with solar and cosmic radiation, as well as comets, asteroids, and meteoroids

Question 7

What is convection and how is it involved in earth’s systems?

Answer 7

Convection is the simultaneous movement of heat and mass

Radioactive decay from earth’s core drives mantle convection, creating movement, formation, and destruction of plates

Also convection in atmosphere of warm/cold air

also convection in hydrosphere, thermohaline circulation

Question 8

Definition of mineral/how do they form?

Answer 8

Defintion: naturally occurring, inorganic, crystalline structure, definable chem composition

form in one of the following ways:

1) cooling of magma
2) recrystallization
3) precipitation from a liquid

Question 9

Know major mineral groups, examples of each, and their importance

Answer 9

Silicates: silicon and oxygen, common in most rocks, ex: quartz, feldspar, mica, zircon, olivine, clay minerals

Carbonates: soft, form in presence of water, ex: calcite, dolomite, aragonite

evaporites: subjected to intense evaporation, indicates arid climates, ex: halite, gypsum, anhydrite

native elements, sulfides, oxides: metals in particular, plus magnetite (oxide)

Question 10

Which mineral group is the most common?

Answer 10

Silicates

Question 11

Which mineral group(s) form in association with water?

Answer 11

Carbonates

Question 12

List key properties used to identify minerals

Answer 12

Color, streak, density, effervescence, magnetism, taste, fluorescence, hardness, cleavage

Question 13

How and where do igneous rocks form?

Answer 13

Form from cooling of magma that comes hot deep crust and upper mantle

Question 14

Compare and contrast granite (con. crust) and basalt (ocean crust) based on intrusive/extrusive origin, cooling rates, mineral size, and composition.

Answer 14

Granite: high silica, high viscosity magma, intrusive origin, slow cooling, large crystals

Basalt: low silica, low viscosity magma, extrusive origin (but eruptions are non explosive), fast cooling, small crystals

Question 15

Which rock types represent violent, volcanic eruptions?

Answer 15

Rhyolite, andesite

Question 16

How and where to sedimentary rocks form?

Answer 16

Forms through weathering (physical/chemical), then erosion, then transportation, then deposition and compaction…all on earth’s surface

Question 17

What factors are important to sedimentary formation?

Answer 17

Weathering, erosion, lithification

Question 18

What is the difference between clastic and chemical sedimentary rocks?

Answer 18

Clastic: loose sediment that is lithified via burial, compaction, and cementation

Chemical: chemical processes like dissolution, and precipitation break down/build up ions

Question 19

How and where do metamorphic rocks form?

Answer 19

recrystallization of pre-existing rocks without melting in deep crust/upper mantle

Question 20

Compare and contrast foliated slate (low grade) and gneiss (high grade) vs non foliated quartzite and marble

Answer 20

slate: small crystals, subtle foliation
gneiss: high temp and pressure, large crystals, foliation

quartzite and marble: no foliation, small, grainy crystals

Question 21

What are the types of metamorphism?

Answer 21

regional: high pressure and temp over large regions (mountain building, plate collisions)
contact: heat/fluid from lava/magma, low grade

Question 22

What is the rock cycle?

Answer 22

Transformation of one rock type into another through 1) melting 2) heat and pressure and 3) erosion and cementation

Question 23

What early theories serve as the basis for plate tectonic theory?

Answer 23

Continental drift + seafloor spreading

Question 24

What evidence supports continental drift?

Answer 24

fit of the continents
fossils
rocks
mountain ranges
climate belts

Question 25

What is Pangea?

Answer 25

the supercontinent that preceded our modern day continents

Question 26

Why was Wegener’s hypothesis not initially accepted?

Answer 26

He had no mechanism for HOW the continents drifted, only that they did

Question 27

What evidence supports sea floor spreading?

Answer 27

mid ocean ridges
age of seafloor
thickness of sediment
paleomagnetism
magnetic reversals

Question 28

What role does convection play in plate tectonics?

Answer 28

Radioactive decay from earth’s core drives mantle convection, creating movement, formation, and destruction of plates

Question 29

What are ridge-push/slab pull?

Answer 29

Plates pushed away at ocean ridges (hot, less dense)

Plates pulled down in subduction (cold, dense)

Question 30

What are the three plate boundary types and what features are found with them?

Answer 30

Divergent (mid-ocean ridge, rift, normal faults, passive margins);

convergent, 3 types: ocean-ocean, ocean-continent, continent-continent (subduction zones, volcanic arcs, trenches, Wadati-Benioff Zone, reverse faults, folds, active margins),

transform (strike-slip faults, off-set mid-ocean ridges);

Question 31

Which boundary creates crust? Destroys it?

Answer 31

creates: divergent
destroys: convergent

Question 32

What is the average rate at which plates move?

Answer 32

1-15/2-20 cm per year

Question 33

What is a mantle plume/hotspot?

Answer 33

mantle plume: stationary heat source in mantle

hot spot: fixed heat source that generates a trail of volcanoes as plates move over it

Question 34

What are asthenosphere and lithosphere? What roles do they play in tectonic theory?

Answer 34

Tectonic plates formed w/in lithosphere, interacting and moving over plastic asthenosphere

Question 35

What are all those fun principles used for relative age dating?

Answer 35

Superposition, Lateral Continuity, Original Horizontality, Inclusions, Cross-cutting Relations, and Faunal Succession

Question 36

What is an unconformity? What are the three types of unconformities and how do you identify them?

Answer 36

definition: erosional gaps in the geologic record, formed by uplift and erosion

angular unconformity, disconformity, nonconformity

Question 37

How are fossils used to date rocks?

Answer 37

fossils have a geologic range, spanning from their first appearance in a specific strata to their last appearance

Question 38

What is the range zone vs concurrent range zone of fossils?

Answer 38

range zone: rock body that represents the total life span of a specific fossil

concurrent rang zone: overlapping ranges of 2 or species

Question 39

What makes a good index fossil?

Answer 39

abundant, widely dispersed, easy to identify

Question 40

What are some problems in using fossils for correlation

Answer 40

sudden disappearance may mean extinction or they moved out

first appearance may mean they evolved there or moved in

reworked fossils could have been eroded and transported from elsewhere

Question 41

What are the different methods used to calculate the age of the earth?

Answer 41

Biblical, Evolution (6,000 years old), Deposition Rates (million-billion), Ocean Salinity (100 million), Cooling Rate (20-40 million), Radioactive decay (becquerel and curie)

Question 42

What is the age of the earth according to geologic theory?

Answer 42

4.56 billion years old

Question 43

How we can use radioactive decay to determine a numerical age

Answer 43

through parent isotopes, daughter isotopes, and half lives

Question 44

What is an isotope?

Answer 44

varieties of the same element with equal atomic numbers but different mass numbers (varying neutrons)

Question 45

What are parent atoms, daughter atoms, half lives?

Answer 45

parent: what you start with
daughter: product of decay of parent
half life: the time it takes for half of the parent atoms to decay into daughter atoms

Question 46

Why must minerals behave as such a closed system?

Answer 46

so that it cannot exchange isotopes with the environment any longer to provide an accurate age

Question 47

How does carbon-14 dating work and what does it date?

Answer 47

Carbon-14 created by cosmic radiation bombarding N-14 atoms, consumed by plants/animals, then trapped and decays back into N-14

dates organic material containing carbon in sediments

Question 48

Know how to calculate an age given the proportion of parent to daughter atoms and the half-life of an isotope

Answer 48

hell yeah brother,

100-50-25-12.5

Question 49

How was the geologic time scale formed and what is it based on?

Answer 49

Formed by several scientists, primarily Arthur Homes in 1913 (uranium dating), based on changes on fossils which mark boundaries

Question 50

Know the hierarchy of geologic time units: Eons, Eras, Periods, and Epochs. Which represent longer/shorter periods of time?

Answer 50

you should know this bitch