NJIT Physics 203 Earth in Space Exam 2

geology

the study of the Earth's geosphere

geosphere

the solid part of the earth

mineralogy

the study of minerals

mineral

Any naturally occurring solid, inorganic object with a definite chemical structure

properties of a mineral

color, streak, luster, light transmittance, hardness, tenacity, cleavage, habit, density, specific gravity, taste, smell, magnetic properties, chemical reactivity

color (mineral property)

least reliable way to identify a mineral

streak (mineral property)

the color of a mineral in its powder form is more reliable

light transmittance (mineral property)

transparent: see through

opaque: no light

translucent: kind of see through

hardness (mineral property)

resistance to scratching/rubbing without breaking

mohs scale

measures hardness of a mineral from 1-10

1: talk (baby powder)

10: diamond

you can scratch minerals together to see which is harder

pocket knife: 4.5

fingernail: 2.5

tenacity (mineral property)

resistance to breaking/deforming

to measure it you need to break or at least deform the mineral

no scale to measure it

cleavage (mineral property)

crystal geometry of a mineral when you break it (classified by orientation of the cleavage planes)

habit (mineral property)

the crystal geometry of a material if it forms without confinement

(most of the time, it is not realized as most minerals form with at least some confinement)

density (mineral property)

= mass/volume

every mineral has its own density

specific gravity (mineral property)

the density of an object in comparison to the density of the water

= density of substance/density of water

magnetic properties (mineral property)

can be tested if it attracts metal

silicates

the most common type of mineral

based on SO4, tetrahedral structure

types of silicates in increasing complexity

nesosilicates, sorosilicates, single chain inosilicates, double chain inosilicates, phyllosilicates, tectosilicates

types of silicates from darkest to lightest

nesosilicates, sorosilicates, single chain inosilicates, double chain inosilicates, phyllosilicates, tectosilicates

darker silicates are more dense due to the most amount of metals such as magnesium and iron

lighter silicates are less dense due to the smaller amount of metals

sulfates

mineral group based on sulfur oxygen

carbonates

mineral group based on carbon oxygen

oxides

mineral group based on metals connected with oxygen

- iron (red), aluminum, copper (green)

halides

a mineral group based on the halogens

native elements

based on one atom type only

- pure iron/gold

petrology

the study of rocks

rock

any naturally occurring, inorganic solid that is a mixture/aggregate of minerals with no definite chemical structure

petrography

the study of the classification of rocks

petrogenesis

the study of how rocks form

types of rocks

igneous, sedimentary, metamorphic

igneous rock

molten rock that crystallizes into solid rock

extrusive igneous rock

VOLCANIC: molten rock (lava) that came out of the Earth, cools off and then crystallizes

- aphanitic and glassy (short cooling period)

intrusive igneous rock

PLUTONIC: molten rock (magma) that stays in the center of the Earth and then cools off and then crystallizes

- phaneritic and pegmatitic (long cooling period)

texture of igneous rock

records the cooling history of the rock

- Pegmatic: extremely coarsely grained, rough to touch

- Phaneritic: coarsely grained

- Aphanatic: fine grained

- Glassy: extremely fine grained, soft to touch

quenching

fast cooling, leads to glassy rock

ex. molten rock meets water

Porphyritic

describing an igneous rock composed of both large and small crystals due to an interrupted cooling history

types of silicates

- malfic: hottest / most dense / darkest

- intermediate

- felsic: coolest / least dense / lightest

bowen's reaction series

MALFIC: extrusive: basalt // intrusive: gabbro

INTERMEDIATE: extrusive: andesite// intrusive: diorite

FELSIC: extrusive: rhyolite // intrusive: granite

sedimentary rock

parts of a rock that were broken down from larger rocks caused by wind or rain

lithify

to become rock

classification of weathering agents

detrial/classic: by physical forces

- texture (size of sediment) and shape (distance of erosion) and sorting (energy of erosion: high energy is poorly sorted (river, glacier) low energy is well sorted (stream))

chemical: by chemical reactions

biogenic: by lifeforms

shape of sedimentary rocks

angular: very short erosion

sub angular: short erosion

sub rounded: long erosion

rounded: very long erosion

wentworth scale of sediment textures

gravels: conglomerate

sand: sandstone

silt: siltstone

clay/mud: shale

chemical sedimentary rock

mineral composition: limestone, dolostone, chert

biogenic sedimentary rocks

chalk

coquina

coat from peat (animals and plants that decompose and put under pressure together)

metamorphic rock

formed by hot temperatures, high pressure and chemical reactions

classified by:

- heat (contact metamorphism)

- pressure (regional metamorphism)

- chemical reaction (hydrothermal metamorphism)

parent and daughter rock

pre-existing rock and changed/new rock

foliated/folded rock

formed by applying pressure in one direction

- slate, phyllite, schist, gneiss

non foliated rock

formed by applying pressure in all directions

- anthracite, marble, quartz

rock cycle

always changing, not static

migmatite

parts of a rock are melted but other parts are not

cannot be classified because there is no agreement

earth composition

70% water

30% land (continents expand many miles into the sea: continental shelf)

uppermost part of the continent

sedimentary rock

drill more you reach igneous rock (FELSIC)

drill more you reach rhyolite and granite

bottom of the ocean

sedimentary rock

drill more you reach igneous rock (MALFIC)

drill more you reach basalt and gabbro

layers of the earth

core: center of earth, most dense (iron and nickel)

- inner core SOLID

- outer core MOLTEN

mantle: less dense, iron rich silicates, made of rocks and minerals, broken into the mesosphere

crust: thinnest layer of earth, least dense, iron poor silicate rock

asthenosphere

layer of weak rock

seismic waves

waves produced by earthquakes

two types:

- p waves (primary and pressure): force directly onto an area, propagate through liquid and solid, TRAVEL FASTEST and are detected first

- s waves (secondary, shear, solid): force directed across an area, only propagate through solid

shadow zones

locations on earth only p waves are sensed because the earthquake was across the earth and S waves cannot travel through the molten outer core

earth's age and formation

4.5 billion years

on formation it was entirely molten and the denser materials sunk to the center due to gravity. Larger planets have a greater DIFFERENCITATION because they have a larger gravitational force

3rd planet from the sun

-inner core is detached from the rest of the earth

mars

4th planet from the sun

weaker gravity than earth's so it is less differentiated, it has more iron on the surface which is why it is red

magnetic field

created by the outer molten core layer bc of iron and nickel

BEGINS: magnetic north pole

ENDS: magnetic south pole

these poles are different from the geographic poles

reverses itself every 100,000 years

magnetic reversals in every layer of earth

solar wind

stream of charged particles (protons and electrons) from the sun

van allen belts

charged particles (from solar wind) are trapped in earth's magnetic field and collide with molecules in the atmosphere and give off energy in the form of light:

- aurora borealis: northern lights

- aurora australis: southern lights

plate tectonics

fundamental theory of geology proposed by Alfred Wegener

Alfred Wegener

climatologist who died at 50 on an expedition studying ice in Greenland, wrote the book "The origins of continents and oceans"

proposed the hypothesis of continental drift (that the continents were once connected and drifted apart)

- continental shape: west Africa and east South America

- rock type

- mountain ranges

- ancient climate

- fossils of land animals

post WWII US navy founds the US Office of Naval Research, who discovered:

- continental shelves

- oceanic ridges: mountain ranges at the bottom of the sea

- continuum of rock ages (rock closest to midatlantic ridge is youngest and as you get closer to the continents it gets older)

- continuum of sediment thickness (thickens are you move away from the midatlantic ridge)

theory of plate tectonics

the lithosphere of the earth is broken into 20 pieces called tectonic plates that float in the asthenosphere and are pushed by convection cells

types of energy

conduction: heat transferred due to direct contact

convection: heat transferred due to fluid (liquid or gas) moving from one place to another

radiation: energy transferred due to electromagnetic radiation

where does geothermal energy come from?

radioactive decay from within the earth

divergent plate boundaries

two tectonic plates are being pushed away from each other

- if the two plates separate, molten rock comes up and cools, creating newborn rock

- the youngest tectonic plates are at divergent plate boundaries

- the Atlantic Ocean is getting smaller every year by a few cm

convergent plate boundaries

two tectonic plates are being pushed toward each other and collide

- where oldest tectonic plates are found

1. oceanic + continental = subduction

2. oceanic + oceanic = subduction

3. continental + continental = folded mountains

- if no continent subdues it causes folded mountains such as the Himalayas

continental volcanic arc

a chain of active volcanoes

- Andes mountains

wilson cycle

birth, evolution and death of an ocean basin

-dying ocean: pacific

-narrowing sea: mediterranean

transform fault boundary

two tectonic plates slide past each other, earthquake happens when they are able to free themselves

- oceanic + oceanic: Queen Charlotte Fault

- continental + continental: San Andres Fault

Hawaiian islands

not formed by tectonic plate boundary

namatath: a chain of islands formed by a hot spot

formed by a hotspot where mantle ploom occurs

supercontinent cycle

every 1/2 billion years

- last supercontinent: Pangea

- last super ocean: Panthalassa

quasar

a galaxy billions of years away

orology

the study of mountains

orography

the classification of mountains

orogenesis

the study of the creation of mountains

ductile deformation

the warping of the shape of a rock which causes folds in the rock due to small forces applied over a long time

brittle deformation

when a rock breaks due to a large force being applied over a short time, causes faults (most are within tectonic plates)

anticline, syncline

baby mountain (dome - folded mountain), baby valley (basin - valley)

cordillera

parallel chains or ranges of mountains

dip-slip fault

vertical breaking

strike-slip fault

horizontal breaking (does not form mountains, largest one is a tectonic plate)

fault scarp

steep cliff caused by brittle deformation

3 parallel mountain ranges

when a tectonic plate subducts under another plate the felsic rock melts and is forced up, then under larger pressure intermediate rock melts and is forced up, then under the largest pressure malfic rock melts and is forced up

accretion

gaining of mass through sticky collisions

accretionary wedge

when a continent gains mass from subduction of tectonic plates sinking underneath it

terrane

a part of a accretionary wedge that has a unique geological history different than its neighboring terrane

craton

the center of a continent that is the oldest part of the continent

isostasy

vertical motion of a tectonic plate

what happens to a mountain as wind and rain strip sediment off the mountain

it becomes taller because the continent gets lighter and is pushed up

seismology

the study of any vibration "seismic activity" whatsoever in the geosphere

elastic potential energy

energy stored in something because you compress it

elastic rebound

the mechanism by which an earthquakes happens

fault creep

the slow continuous motion at a transform fault boundary

- active fault creep: NOT likely for an earthquake to happen

- no active fault creep: it is DEFINITE that an earthquake happens

focus

the source or origin of a seismic waves

epicenter

the point on the surface directly above the focus

seismometer

detects seismic waves/energy