Earth Sci I - Exam 1

Milky Way

the galaxy our solar system is in

100 billion

How many galaxies are in our universe?

13.7 billion years ago

When did the Big Bang occur?

expanded faster than speed of light

hot energy located at a single point did what to form space

matter
nebulae
dust and gas

As space cooled, energy was converted to ___________ which coalesced into _____________ (clouds of _______ and _____).

because light coming to us from other stars is red shifted (lower pitched if it were sound)

How do we know the earth is still expanding?

the color spectrum

Each element in a star absorbs a special part of what?

When the absorption lines are farther into the red than they should be

how can we tell the galaxy is moving away?

the dots we drew on expanding balloons

Galaxies farther away move faster away than the ones closer, like what example we saw in class?

first
heavier

the ________ stars fused the light elements that formed in the Big Bang, making ________ elements.

dust
large
heavier
sun

Stars that inherit the _______ from exploded, _______ stars inherit their __________ elements. This is how our ______ (and solar system) got these types of elements

the moon-forming impact

The Earth cooled and differentiated into layers, only to be disrupted by what?

outer
magnetic field
biosphere, atmosphere, hydrosphere

The ______core is still a churning, molten, metallic layer resulting in a protective _______________ __________ for our planet which protects our _______________, _________________, and _________________.

crust and mantle

the outer part of our planet is divided into two parts:

seismic waves
faster

the mantle is denser than the crust, and we know this because scientists have observed ___________ ________ traveling ___________ through this layer.

composition and density
mechanical properties

The Earth is divided into layers based on ____________ and _____________ (crust, mantle, and core) and based on _____________________ ____________________/breaking vs. bending vs. flowing (lithosphere, asthenosphere, lower mantle, inner core, and outer core).

continental and oceanic

two primary types of crust:

continental crust

less dense, light in color, and contains lots of quartz (froth)

oceanic crust

dense, dark, cold, and contains quartz + heavier elements like iron and magnesium.

continental drift

hypothesis that tried to explain why the continents (a) look like they fit together, (b) have glacial deposits that line up when the continents are joined, (c) have tropical rock deposits that do the same, (d) share fossils of animals that couldn't cross an ocean, and (e) share symmetrical mountain belts.

how the continents were able to move

Continental drift did not explain what?

Harry Hess

began mapping the ocean floor early in his career (in the 1940's), but he couldn't piece together what his data meant

Marie Tharp

In 1953, which geologist fit the data together and figured out that a large mountain range ran through the middle of the Atlantic Ocean and that right in the middle of the mountains was a deep valley? She thought the valley was a place where the mountains were breaking apart, magma was rising, and cooling into new ocean crust.

sea-floor spreading

hypothesis which states that magma erupts at mid-ocean ridges making new ocean crust and ocean crust is destroyed at trenches by sinking into the mantle.

plate tectonics

The work of Tharp and Hess started the transition for the scientific community to believe the Theory of ?

Earth's magnetic field has flipped north to south or south to north every 20,000 years.

layered lava flows show that

iron grains
magnetic north
magma

We know this because _______ _________ in the iron-rich rocks that make up the ocean floor align with (or point towards) _____________ _________ when those rocks cool from ____________.

polar wander

Tectonic plates that moved across the Earth's surface appear to have magnetically 'pointed' toward wandering north poles (called ___________ ____________). Really, it's just that the plates have moved and rotated and north stayed in one spot.

symmetrical

Magnetic stripes on the sea floor are ________________ around mid ocean ridge spreading center. Thicker stripes indicate times that spreading was quicker

much older
active margins
passive margins

Continents are _______ ___________ than ocean crust because they are less dense and therefore not likely to sink into the mantle. Ocean crust sinks below continental crust at __________ ____________. At ______________ ____________, it simply connects and grades into the continental crust.

supercontinents
Pangea
oceans

Many ___________________ existed and broke apart before ____________. When these continents broke apart, they resulted in lots of _________. When they came together, one large ocean formed as a consequence.

convergent, divergent, transform

three types of plate boundaries:

crust-ocean-continent
ocean-ocean
continent-continent

three types of convergent boundaries

colder, denser
subducts

at ocean-continent and ocean-ocean boundaries, the _____________, ________________ oceanic plate subducts below the other plate.

buoyant (less dense)

continental plates are more _______________ than oceanic plates.

volcanism

subduction zones often result in _______________.

Divergent boundaries

present at mid-ocean ridges where new crust is made.

transform boundaries

usually short and neither create nor destroy crust

absolute or relative

plate motions can be described in two ways:

hot spot volcanism

results in lines of volcanoes located far from plate boundaries

sedimentary, metamorphic, and igneous

the rock cycle processes _______________________, _____________________, and _________________ rocks.

mineral

defined as a naturally occurring, geologically formed, inorganic solid with crystalline structure defined by a definite chemical composition.

Naturally occurring and geologically formed

can't be man made

synthetic materials

Manmade minerals

Solid

It's not a liquid or a gas.

Has a crystalline structure defined by a chemical composition

The atoms are arranged in a specific order and are made of specific, reoccurring elements that can be written as a chemical formula

Inorganic

Typically, you don't get hydrogen-carbon bonds.

solidification, precipitation, solid state diffusion, biomineralization, or precipitate from a gas

Minerals can grow through

melting, dissolving, or chemical reactions.

Minerals can be destroyed through

Euhedral crystals

pointy because they grew into open spaces

Anhedral crystals

have mashed up sides (like pancakes poured too close together on a pan) because they grew in tight spaces.

color and streak

mineral properties for identification

streak

more trustworthy because it crushes the mineral on a ceramic plate into a powder.

luster

describes how the surface scatters light

scratching the mineral against surfaces like your finernail, a penny, or glass that have defined hardnesses.

Hardness is tested by

gravity

Any two objects with mass attract each other.

The distance between the objects and their relative masses

what determines how strong the pull of gravity is?

Ionic bonds

When one ion provides an electron to another, both may have filled shells. This produces a cation and anion (opposite charges) that attract each other.

Metallic bonds

Free flowing electrons move through a field of positively charged metal ions. Electrons are shared and this is part of what gives metals their flexibility and conductivity.

Elements

pure substances that cannot be separated into other materials.

molecule

two or more atoms bonded together. These can be the same or different types of atoms (elements).

compound

pure substance that can be divided into two or more elements (molecules on repeat).

chemical formula

recipe that describes (1) the elements and (2) their proportions to each other.

Crystals

single, continuous pieces of crystalline solid
Typically bounded by flat surfaces (crystal faces)

Gemstones

piece of a mineral crystal that may be cut and polished for jewelry.
Crystals interact with light to create attractive beauty.

Max van Laue

Proposed X-ray study of minerals in 1912

X-ray diffraction (XRD)

still used to decipher minerals.
X-ray beam passed through crystal creates distinctive pattern
Diffraction pattern related to arrangement of atoms in crystals

crystal lattice

Atomic arrangement is called

Polymorph

same composition; different structure
Example: Diamond and graphite are made entirely of carbon (C).
Diamond—atoms arranged in tetrahedra; hardest mineral
Graphite—atoms arranged in sheets; softest mineral

Seed crystal

tiny early crystal acts as a seed for further growth.
Atoms migrate to the seed and attach to the outer face.
Growth moves faces outward from the center.
Unique shape reflects the crystal's internal atomic order.

Color varieties

often reflect trace impurities.

Specific gravity

is "heft"—how heavy it feels.
Represents the density of a mineral
Mineral weight over the weight of an equal water volume

Crystal form

describes how a crystal grows through time.
A single crystal with well-formed faces, or
An aggregate of many well-formed crystals
Arrangement of faces reflects internal atomic structure
Records variation in directional growth rates
Blocky or equant—equal growth rate in three dimensions
Bladed—shaped like a knife blade
Needle-like—rapid growth in one dimension, slow in others

Fracture

describes how a minerals breaks in ways that reflect atomic bonding. Fracturing implies equal bond strength in all directions.

Cleavage

describes a tendency to break along planes of weaker atomic bonds.
Cleavage produces flat, shiny surfaces
Described by the number of planes and their angles
Cleavage (how a mineral breaks) can sometimes be mistaken for crystal form (how a mineral grows)
Cleavage is throughgoing; it often forms parallel steps.
Crystal faces only occur on external surfaces.

Effervescence, Magnetism, taste

Special physical properties

anion (negative ion)

Minerals are classified into groups by their dominant ______________.

Silicates

most common minerals.
Constitute almost the entire crust and mantle of Earth

Industrial minerals

raw materials for manufacturing

Ore minerals

sources of valuable metals

Gem minerals

valued for ability to be polished and set into jewelry

diamonds

originate under extremely high pressure.
Rifting causes deep-mantle rock to move upward. found in kimberlite pipes.

Echo-sounding (sonar)

allowed rapid sea-floor mapping.
Sea-floor maps created by ships crossing the oceans.

Bathymetric maps

are now produced using satellite data.

paleomagnetism

The study of fossil magnetism

Layered basalts

record magnetic changes over time

inclination and declination

indicate change in position

Isotopic dating

gives the timing of polarity reversals.

lithosphere

Tectonic plates are fragments of

Active margins

near plate boundaries.

Passive margins

far from plate boundaries.
Earthquakes common along active margins.

Passive-margin continental crust

thins seaward.
Traps eroded sediment.
Develops into the
continental shelf.

Howard Foster

a young deaf graduate student from Boston, was the asked to map the locations of Earthquakes occurring on the seafloor. Underwater landslides from these Earthquakes had been destroying phone cables. Tharp and Foster discovered a pattern.

Pillow basalt

magma quenched at the sea-floor

Dikes

preserved magma conduits.

Gabbro

rock formed by cooling of deeper magma.

Oceanic transforms

offset the mid-ocean ridge axis

Continental transforms

cut across continental crust

Ridge-push

elevated MOR pushes lithosphere away.

Slab-pull

denser subducting plate is pulled downward.