Physical Geology Unit 1

Front 1

What is the scientific method?

Back 1

1. observe
2. hypothesize
3. test
4. theory
5. model

Front 2

What is a nebular hypothesis?

Back 2

A slowly rotating sphere contracts. Spins faster and then flattens. Matter at the middle becomes proto-sun. Proto-sun becomes dense and hot (nuclear fusion). Gas condenses and collides with dust to form planetismals. Those collide to form planets.

Front 3

How old is the Earth?

Back 3

4.6 Ga (we can tell from the meteorites and the moon)

Front 4

How was the moon formed?

Back 4

A Mars-sized body hit earth approximately 4.5 Ga ago, tilted the Earth's spin axis. Material that was hit flew off and formed the moon.

Front 5

What is the layered structure of the Earth?

Back 5

1. Crust (0-40km)
2. Mantle (40-2890km)
3. Liquid iron outer core (2890-5150 km)
4. Solid iron inner core (5150-6370km)

Front 6

What are the types of seismic waves?

Back 6

1. compressional: P-waves; pas through solids, liquids and gasses
2. shear: S-waves; pass through solids ONLY

Front 7

Which crust is denser:
Continental
Oceanic

Back 7

Continental crust is less dense and thicker than oceanic crust.

Front 8

Keypoints about the mantle

Back 8

*takes up most of the planet
*high-density silicate minerals
*3.4 g/cm3
*upper is relatively strong and rigid
*lower is weak and deformable, solid but plastic

Front 9

Keypoints about the outer core

Back 9

*mostly made of iron, but also nitrogen, sulfur, and oxygen
*liquid because of temperature
*11 g/cm3

Front 10

Keypoints about the inner core

Back 10

*mostly made of iron, but also nitrogen
*solid because of pressure
*13 g/cm3

Front 11

What are the zones of strength?

Back 11

*Lithosphere: crust + top of mantle (100 km); relatively cold, strong, and rigid
*asthenosphere: weaker part of the upper mantle; hot, weak, ductile (think hot wax or silly putty solid that flows)

Front 12

What is the temperature gradient?

Back 12

Temperature gradient is largely responsible for plate tectonics.

Front 13

What happens when plates age?

Back 13

They move away from the ridge, cool down, and become denser. They eventually become denser than the underlying mantle, and sink. This causes plate movements.

Front 14

What are the leading science paradigms?

Back 14

*physics: relatively; quantum mechanics
*biology: evolution by natural selection; DNA
*chemistry: atomic structure; thermodynamics
*GEOLOGY: PLATE TECTONICS

Front 15

PANGEA!!!

Back 15

the super-continent that separated because of plate tectonics

Front 16

What are seafloor magnetic anomalies?

Back 16

*basalt is extruded at ocean ridges
*basalt records the magnetic field at the time of cooling
*crust moves away from the ridges and becomes older
*has symmetrical polarity pattern

Front 17

What is strange about the magnetic timescale?

Back 17

sometimes a compass points north, sometimes south

Front 18

What are some magnetic anomalies?

Back 18

*youngest rocks are near a ridge
*oldest rocks are near a continent

Front 19

Divergent boundaries (definition and example)

Back 19

*when two continents separate
*East African Rift, Rhine Valley
*occurs at zones of upwelling mantle; produces new oceanic crust; basaltic volcanism; causes small shallow earthquakes; high heat flow

Front 20

Continent-continent convergent boundaries (definition and example)

Back 20

*when two continents come together
*no where to go but UP!
*crustal thickening; folded mountains; earthquakes

Front 21

Ocean-continent convergent boundaries (definition and example)

Back 21

*ocean and continent plates coming together
*SUBDUCTION
*volcanic mountain chain; folded mountains; deep earthquakes

Front 22

What are subduction zone earthquakes?

Back 22

Subduction zone earthquakes are less frequent at increasing depth, but with greater intensity.

Front 23

Ocean-ocean convergent boundaries (definition and example)

Back 23

*two ocean plates come together
*the denser plate is subducted
*oceanic trench; volcanic island arc; deep earthquakes

Front 24

CONVERGENT BOUNDARIES

Back 24

*explosive andesitic volcanism
*intrusion of granite at depth
*large earthquakes, shallow to deep
*metamorphism, folds, thrust faults

Front 25

TRANSFORM BOUNDARIES

Back 25

*no igneous activity
*no metamorphism
*large, shallow earthquakes
*strike-slip faults

Front 26

What's so cool about plate tectonics?

Back 26

All the exciting stuff happens on the edge of the plates! (earthquakes, mountains, volcanoes, etc)

Front 27

What is the principle of uniformitarianism?

Back 27

"The present is the key to the past"

Front 28

Define ionic, covalent, and Van der Waals chemical bonding.

Back 28

*ionic: attraction of oppositely charged ions; intermediate strenght; example=halite
*covalent: electron sharing; very strong!' example=diamond
*Van der Waals (intermolecular bonding): weak electrical bonding; example=water

Front 29

Why do geologists care about bonding?

Back 29

Chemical bonding effects:
*crystal structure
*cleavage
*hardness

Front 30

What are minerals?

Back 30

*naturally occurring
*crystalline substance
*inorganic
*specific chemical composition
*MINERALS CANNOT BE DIVIDED MECHANICALLY INTO SMALLER COMPONENTS

Front 31

What class of mineral is most abundant in the Earth's crust?

Back 31

Oxides and hydroxides.

Front 32

Which minerals are rock-forming?

Back 32

Silicates

Front 33

How does the Si:O ratio increase?

Back 33

*from the mantle to the crust
*olivine--pyroxene--amphibole--micas--feldspars

Front 34

What are some infamous cation substitutions?

Back 34

Fe2+ and Mg2+
K+ and Na+
Al3+ and Si4+
Ca2+ and Na+

Front 35

What (and explain) are the physical properties of minerals?

Back 35

*hardness: determined by the strength of a mineral's chemical bonds
*cleavage: how a rock will slit away

Front 36

Important information about minerals

Back 36

*important as natural resources, for Earth's structure and acts as 'archives' of the geologic past
*compositions reflect the abundance of elements (Si and O most common in the crust)
*compositions vary within defined limits (for example, by cation substitution)
*properties reflect composition and bonding

Front 37

minerals found in mantle rocks

Back 37

*olivine
*pyroxene

Front 38

minerals found in crustal rocks

Back 38

*amphibole
*mica
*feldspar
*quartz

Front 39

What are rocks?

Back 39

Rocks are the building blocks of our planet. They are naturally occurring aggregates of minerals; some rocks are aggregates of non-minerals solid matter (coal or obsidian)

Front 40

How do we ID rocks?

Back 40

*mineralogy (what minerals make up the rocks)
*texture: shapes and sizes of the mineral grains and how they are put together

Front 41

What are the rock types?

Back 41

*igneous: melting of rocks in hot, deep crust and upper mantle
*sedimentary: weathering and erosion of rocks exposed at surface
*metamorphic: rocks under high temperatures in deep crust and upper mantle

Front 42

Igneous rocks

Back 42

*Extrusive: form when magma erupts at the surface, rapidly cooling to fine ash or lava and developing tiny crystals.
*intrusive: crystallize when molten rock intrudes into unmelted rock masses in Earth's crust
*intrusive are coarser.
*low Si=darker; high Si=lighter

Front 43

Sedimentary rocks

Back 43

*form from weathering and deposition
*created by weathering, transported by erosion, deposited as sediment on land or in water, form parallel layers, lithify under water, precipitated, deposited in the ground.

Front 44

Metamorphic rocks

Back 44

*form from heat and pressure

Front 45

ROCKS

Back 45

*rocks are aggregates of minerals
*individual minerals in a rock retain their own properties
*properties of the rock are controlled by
1. minerals in the rock
2. the formation process of the rock
*igneous, sedimentary, and metamorphic rocks
*the continual transformation of Earth materials from one rock type to another is known as the rock cycle