Exam 1 Earth Science 2

Differentiated

the earth having different layers including: crust, mantle, and core

What are mainly made of silicate of the earth layers

the crust and mantle are mostly made of silicate

What is the core made up of mainly?

iron

What are parts of the Mantle?

Lithosphere

• cold

• makes up crust and part of the upper mantle

Asthenosphere

• beneath the mantle

• flows, but is solid

  • like putty

very hot

How do we know the structure of the earth?

Using earthquakes and volcanoes to image the mantle and core to create images through waves

What are the two types of Seismic Waves

P-waves travel through solid and liquid waves like waves

S-waves travel through solid only, not really visible but can be felt with ground shaking from an earthquake for example

Hydrosphere

• Oceans: 97.5% (and rising)

• Glaciers ~ 2% (and dropping)

• groundwater ~1%

• lakes, rivers, & streams -0.1%

• clouds: <0.001%

Does the atmosphere exist?

yes

Magnetic Field

caused by convection of liquid iron in outer core, it is a giant magnet that can shift location of its poles, it switching polarity cannot be predicted. it also causes alignment of magnetic minerals

What are atoms made up of?

made up of protons(+), neutrons, and electrons(-)

What are isotopes?

same element atoms with. varying numbers of neutrons

How old is the oldest mineral?

4.4 Ga

Radioactive Decay

can measure how old something is from how if uranium(U) decays into Lead(Pb)

If a rock started with 100 uranium atoms in how many billion years would half of the U atoms would be turned into Pb atoms

it would take 0.7 billion years for half to be turned into Pb atoms

Geologist calculate what to see how old the rock is?

Geologist calculate the decay of specific U (parent isotope) to Pb(daughter isotope) to see how old the rock is

How was the Solar System formed in 3 parts?

1. Solar Nebula: Started as a cloud of gas, molecules, and particles

2. Protoplanetary disk formation: a cloud of gas and dust collapsed due to gravity(gravitational collapse), this collapse caused the cloud to flatten spin faster, forming a spinning disk of material called an accretion disk or protoplanetary disk. most of the material gathered in the center. this hot and dense center of the disk become a protostar, this is the baby sun

3. the center became hot and dense enough it had a nuclear fusion and the protostar was ignited, and the Sun was born.

4. the remaining disk material is where the planets would eventually form

How was the moon formed?

a mars-sized body collided with Earth, causing debris from the Earth’s mantle to turn into the moon.

Evidence for Continental Drift: Alfred Wegener

1. Fit of continents

2. distribution of fossils

3. Distribution of climatic belts

   • glaciated rocks at equator

     • moving from one of the poles to the equator so they were clearly connected

4. continuous geological units and mountain belts

   • common geologic features on different continents

How many tectonic plates are there?

14 tectonic plates

What are the three Plate Boundaries

• Divergent Boundary

• Convergent Boundary

• Transform Boundary

Earthquakes occur at all of these three

What are the two Divergent Boundaries and their example?

Continental  Rifting

• e.g., East africa Rift

Oceanic Rifting 

• e.g., mid-Atlantic Ridge

Divergent Boundaries - Oceanic

• decompression of the mantle leads to partial melting, generating basaltic magmas

• melt rise up to form new oceanic crust

• magnetic stripes

  • alignment of magnetic minerals in crust with Earth’s magnetic field

  • irregular reversals in polarity of the Earth’s magnetic field

• Oceanic crust: mafic

  • basaltic lava at these boundaries(divergent-oceanic)

Divergent Boundaries - Continental

• continental crust is being pulled apart

• If you stretch continent far enough, it’ll eventually transition in oceanic rifting

• Being pulled apart, like taffy it will just expand. Continental crust is very buoyant and doesn't want to subduct so it creates mountains

what are the 3 Convergent Boundaries

Oceanic-Oceanic

Oceanic-continental

continental-continental

Convergent Oceanic-Ocenic

• Subduction Zone

  • more dense oceanic slab subducts under less dense oceanic crust

  • causes island arc volcanism

Convergent boundaries - Oceanic-Continental

• Also a subduction zone

  • oceanic slab (composed of oceanic lithosphere subducts under less dense continental crust

  • driven by slab pull

    • dense material gets pulled underneath due to gravity

  • forms trenches

  • causes island arc volcanism

  • ophiolites: section of oceanic crust and upper mantle that have been pushed up onto land

California was formed by what process and plate?

California was formed through subduction by the Farallon plate

What is an example of the accretionary prisim

Franciscan complex in San Francisco bay area

Convergent boundaries - Continental-Continental

• continental crust is buoyant and does not want to subduct

• leads to very thick crust

• generates large mountain ranges

• Himalayan mountains are just to converging platesW

What are the two Transform Boundaries

transform boundaries - continental

transform boundaries - oceanic

Transform Boundaries - Continental

• near vertical fault

• plates are neither formed or destroyed

• plates simply slide past each other

• ex san andreas fault system

Transform Boundaries - Oceanic

• Decompression of the mantle leads to partial melting, geneating basaltic magmas

• melts rise up to form new oceanic crust

• spreading centers involve sections of transform boundaries and fracture zones

• mid-ocean rides can spread at different rates

• ex: mid-atlantic rift and East Pacific Rift

What are hot spots?

Stationary area deep within the Earth’s mantle where plumes of hot, buoyant material rise to the surface, causing volcanic activity on the overlying tectonic plate as it moves across it

• A hotspot is formed here and the islands formed but the hotspot stays in the same place but the islands will always being moved and new islands being formed but the hotspot stays the same

Where do plumes come from?

• Form at the core and mantle-boundary

What are the different hotspots

• Hawaiian-emperor chain

• easter island(papa nut)

• Iceland

  • also formed due to mid-atlantic ride

• Yellowstone

  • has a volcano

What is magma?

stored at depth beneath volcanoes

What is lava?

magma erupted on surface

Where do Volcanoes occur?

occur at divergent boundaries, convergent boundaries, and hotspots, not transform boundaries

What are the two eruption styles for volcanoes

1. Effusive(vertical): lava pours out of vent or fissure

2. explosive(horizontal): volcanic products are erupted into the air due to gas in the magma

   • very destructive 

   • injects debris high into atmosphere

What are the 4 volcano types?

1. Shield Volcanoes

2. Stratovolcanoes

3. Caldera eruptions

4. Flood basalts

Shield Volcanoes

• low viscosity basaltic lava

  • not explosive, more effusive

• high magma supply rate

• example: Mt. Kilauea

  • Pu’u ‘O’o, a volcanic cone, had an eruption that started in 1983 an ended in 2018

Stratovolcanoes

• formed by a mix of explosive and effusive eruptions of intermediate to felsic lavas

• runny lava from effusive eruptions hardens into solid rock that holds loose ash and debris from explosive eruptions in place

• explosive eruptions usually cause pyroclastic flows

• example: Mount St. Helens

  • after a 198- eruption, it reduced by 15000 ft

Caldera eruptions

• caldera: volcanic depression due to emptying of a magma chamber

• effusive or explosive eruptions can lead to caldera formation

• example: crater lake, Oregon

Flood Basalts

• eruptions of a massive volumes of basaltic magma from long cracks on the ground

• effusive

• have been attributed to the arrival of a new plume

• example: Columbia River Basin

What are hazards that come with Volcanoes

• pyroclastic flow: gravity driven flow of gas, pumice, and ash

• Ash

  • risk of inhalation

  • can block visibility for aircraft

• lava

  • destroys/melts/ burn structures

• lahars: hot or cold mix of water and volcanic debris

  • can flow very fast (10→ 100km/hr)

  • can be generated by melting of snow and ice during eruptions

• Climate change

  • ash and gas can stay in stratosphere for weeks to years

  • short-term cooling

What is a rock

a rock is a naturally occuring solid made up of minerals (or a mass of glass)

What is a mineral

a mineral is a naturally occurring solid with a crystalline structure and definable chemical compositions

Different structures with same chemical composition can result in different minerals. for example?

• graphite and diamonds

• olivine and pyroxene

• calcite and aragonite

What is a Crystalline structure

a crystalline structure is a repeatable structural pattern

• glass is not a crystalline structure

What are the minerals talked about in the Lab

1. Quartz

2. Plagioclase Feldspar

3. Potassium Feldspar

4. Olivine

5. Biotite

6. Amphibole

7. Pyroxene

8. Calcite

Mineral Identification

1. Color: What color is it? Is it transparent or translucent or opaque?

2. Cleavage/Fracture: where does it break?

3. Hardness: How hard is it compared to other minerals?

4. Habit: How does it grow? (equant, elongated, cubic, platy)

5. reactivity: does it have a reaction when in contact with HCI?

Mineral identification: Quartz

1. Color: greyish, transparent, almost white, also pink and purple lightly

2. Cleavage/fracture conchoidal fracture

3. Hardness: 7

4. Crystal Habit: prismatic

5. reactivity: no reaction

Mineral identification: Potassium Feldspar

1. Color: pink/white/gray

2. Cleavage/Fracture: 2

3. Hardness: 6

4. Crystal Habit: prismatic

5. reactivity: no reaction

Mineral identification: Plagioclase Feldspar

1. Color: white/gray/dark gray

2. Cleavage/Fracture: 2

3. Hardness: 6

4. Crystal Habit: blocky/primsatic

5. reactivity: no reaction

Mineral identification: Olivine

1. Color: Olive-Green

2. Cleavage/Fracture: conchoidal fracture

3. Hardness: 6/5-7

4. Crystal Habit: equant

5. reactivity: no reaction

Mineral identification: biotite(mica)

1. Color: black

2. Cleavage/Fracture: 1

3. Hardness: 2.5-3

4. Crystal Habit: platy

5. reactivity: no reaction

Mineral identification: amphibole

1. Color: dark green to black

2. Cleavage/Fracture: 2

3. Hardness: 5-6

4. Crystal Habit: elongated

5. reactivity: no reaction

Mineral identification: Pyroxene

1. Color:dark green to black

2. Cleavage/Fracture: 2 cleavage

3. Hardness: 5-6.5

4. Crystal Habit: blocky

5. reactivity: no reaction

Mineral identification: Calcite

1. Color: white

2. Cleavage/Fracture: 3

3. Hardness: 3

4. Crystal Habit: rhombohedral

5. reactivity: yes it fizzes

What are the 3 types of different rocks

Igneous: the original rock

sedimentary rock

metamorphic

Mafic rocks

• higher density due to the presence of heavier elements like iron and magnesium

• high in minerals such as olivine, pyroxene, and amphibole

• will be darker in color

Felsic

• lower density because of the higher silica content and lighter minerals

• high in minerals such as quartz, potassium feldspar, and sodium-rich plagioclase feldspar

• going to be lighter in color

What is an intermediate rock

more than mafic and less than felsic in silica content

Plutons:

• batch of magma that rose into crust and cooled

Batholiths

• larger plutonic body, much larger than a pluton

Dike

• vertical tabular intrusion of magma into the host rock, then cools

  • Has a pluton and becomes vertical that is a dike

Sills

horizontal tabular intrusion of magma into the host rock then cools.

What are Igneous Intrusions?

1. plutons

2. batholiths

3. dike

4. sills

Sedimentary Rocks: Weathering

Weathering: surface or near surface in-place breakdown of rocks by physical and chemical processes, generates sediment

• Physical weathering

  • joints: Naturally formed fracture on a rock

  • frost/ salt wedging: water freezes into ice // salt forms in the cracks of rocks and expands

  • biological processes: plants and trees break rocks apart

• Chemical weathering

  • dissolution: water or weak carbonic acid can dissolve rocks

  • hydrolysis: interaction with water or carbonic acid can chemically change mineral in rock

  • oxidation: rusting, water or carbonic interacts with iron in rocks

4 types of sedimentary rocks are?

Clastic

Biochemical

Organic

Chemical

Clastic

 Composed of fragments or grains derived from the breakdown of other rocks which were later cemented together

Clastic Process:Clastic Identification

important to know order

• weathering

• erosion

• transportation

• deposition

• lithification/diagenesis: all of the physical, chemical and biological processes that transform sediment into sedimentary rock and that alter the rock after the rock has formed

Clastic Identification

• composed of fragments or grains dervived from the breakdown of other rocks, which were later cemented together

• Identification:

  • Class size: size of fragments or grains makeup up rock

  • Clast composition: what fragments and grains are made up of

    • can give insight on source and transport distance

      • weaker materials break easier and do not travel as far

      • stronger materials don’t break apart as easya nd usually travel further

  • Clast shape: rounded or angular fragments or grains?

    • also give insight on source and transport distance

      • rounder fragments travel futehr

  • Sorting: are the type of fragments the same (homogenous) or different (heterogenous)

  • type of cement: what mineral is holding fragments or grains together?

Clastic Types

• Course sized (>2mm):

  • Breccia (angular clasts)

    • I should know breccia is course sized

  • conglomerates (rounded clasts)

• sand sized (1/16mm - 2mm)

  • arkose (quartz and feldspar)

  • quartz (quartz)

• Fine (1/256 mm - 1/16 mm): siltstone(silt)*

• very fine (<1/256 mm): shale or mudstone(clay

• grain size reflects energy and environment

Biochemical

• formed from material produced by living organisms

• Biochemical limestone: made up calcium carbonate called calcite

  • coral, shells, skeletons

• biochemical chert: made up of silica from shells (tests) of plankton

• a mix of both limestone and chert!

Organic

1. formed from carbon-rich relicts of organisms

   • Coal: organic material (plants) buried under immense pressure and heated

   • Oil shales: organic matter (organisms that died in water column) that sank to ocean/lake floor, was buried, and then heated to right conditions

Chemical

made up of minerals that precipitate directly from an aqueous solution

• precipitate: solid forms from a liquid solution
  
  Chemical Types

  • Evaporites: Salt deposits formed by precipitation from saline water(salt water), water evaporates, leaving behind solid

    • Halite

      • Regular table salt

    • gypsum

  • Travertine: chemically precipitated calcium carbonate

    • Like cave spikes from the bottom and top of the caves are travertine

What are the Visible textures or arrangements of sediments within a rock

• bedding

• ripple

• marks

• cross-bedding

  • angled bedding

• mud cracks

Andrew Wegener proposes what

Continental Drift

Irvine and Runcorn demonstrate what

they demonstrated that the continents have drifted

Tharp and Heezen map shows what

the map shows the North Atlantic rift valley along the length of the ridge

Hess proposes what about oceanic crust

he proposes that oceanic crust is formed at mid-ocean ridges and then returned to the mantle along trenches

Vine and Matthes propose what

they propose that sea-floor spreading may explain magnetic strips along the seafloor

Pitman and Heirtzler did what

their magnetic date confirm symmetric mid-ocean ridge spreading