GEO-4: Quiz #3

Some of the laws enacted to help save lives:

•Alquist-Priolo Earthquake fault zoning act (1972)

• cannot build 50 feet of an ACTIVE fault

• habitable structure (where people live- houses, apartments, etc.)

• active fault= 11,000 or 12,000 some movement

•Field act (1933)

• talks about schools (elementary, middle, high school, college/uni) 

• regulates the construction of school (“earthquake-resistant”)

•National Dam Safety Act (1996)

• to ensure that dams could hold great earthquakes 

•Hospital Safety Act (1983)

• same as the act of 1933 instead of school, it’s hospitals 

•Uniform Building Code

• ensure that all building to ensure safety 

Earth’s Interior 

• Most of our knowledge of Earth’s interior comes from the study of P and S earthquake waves

  • Travel times of P and S waves through Earth vary
    depending on the properties of the materials

  • S waves travel only through solids

Earth’s Layered Structured

• can be described in two ways 

1.Based on Composition – Core, Mantle, Crust
2. Based on physical properties – Inner core, Outer
core, Mesosphere, Asthenosphere, Lithosphere.

(inner core- hot and has a lot of pressure)

Matter and Minerals 

• definition of a mineral 

  • natural

  • inorganic

  • solid

  • have a definite crystal structure

  • have a definitive chemical composition

• rock- any naturally occurring solid mass of mineral or mineral-like matter

• some rocks are made up of mineral or other stuff

Atoms: Building Blocks of Mineral

• atoms

  • smallest particles of matter

  • contains central nucleus with protons and neutrons

    • protons: dense particles with + charge

    • neutrons: dense with neutral charge

  • electrons surround nucleus

    • negligible mass with - charge

atoms (continue) 

• anything with 6 protons is carbon

• protons (+)- number of protons determines what element it is

• neutrons (neutral) 

  • atomic weight (p and n)

• electrons (-)

• proton mass= 1 Amu

• neutrons mass= 1 Amu

• electrons mass= 1/2000 Amu

Chemical Bonding

1) ionic bonds- opposites attract (+)(-)

• most common and easily to break

• Na⁺ + Ch^- = NaCh Halite

2) covalent bonds- share electrons

• strongest bonds

3) metallic bonds- allow electrons to flow

4) van der waals bond- weak

• hydrogen bonds

• important but weak

Optical Properties of Mineral 

• luster- appearance in reflected light 

• color- can vary and is not reliable 

• streak- color of mineral in powered form 

• ability to transmit light- light can travel through a mineral causing it to be translucent or transport 

Some Common Crystal habits 

• crystal shape, or habit 

  • common shapes of crystal growth

a) fibrous

b) bladed

c) banded

d) cubic crystals

Mineral Strength:

how easily minerals break or deform is determined by the bonds

• hardness- ability to resist scratching or abrasion

• cleavage- tendency to break along planes of weak bonds

• fracture- random pattern of breakage

• tenacity- resistance to cutting, bending, breaking, and deformation

• specific gravity- mineral density

Mohs Hardness Scale (hardness)

cleavage

a) 1 muscovite

b) 2 90° feldspar

c) 2 not 90° hornblende

d) 3 at 90° halite

e) 3 not at 90° calcite

f) 4 fluorite

other properties 

• taste 

• smell

• elasticity 

• malleability 

• double refraction 

• magnetism 

• feel 

• reaction with hydrochloric acid 

8 elements

• composed of mineral rocks

• earth’s continental crust

  • oxygen

  • silicon

  • aluminum

  • iron

  • calcium

  • sodium

  • potassium

  • magnesium

uses of clay

• pottery

• dishes- fine China

• toilets

• paper- gives it it shine

(dishes, toilets, paper- percaline (made out of clay))

• pills

• ketchup

• “shakes”

• Oreos

(ketchup, shakes, Oreos- food (modifies the texture doesn’t mess up with our bodies))

• electronics

• tile- roofing tile, wall floor

Silicates vs Nonsilicates 

• 92% of earth’s crust is made of silicates 

• 8% of earth’s crust is made of nonsilicates 

• silicates- silicon and oxygen 

• nonsilicates- no silicon 

  • oxides: hematite

  • sulfides: pyrites

  • sulfates: gypsum

  • halides: halite

  • carbonates: calcite

  • native elements: cooper

Renewable: 

• can be replenished in relatively short time span (human times) 

  • crops, wind, water, etc

Nonrenewable:

• earth has fixed quantities (non-human time)

  • oil, aluminum, natural gas, coal, etc

Mineral Resource and Ore Deposits 

•Mineral resources are occurrences of useful minerals that
could eventually be extracted
•Ore deposits are concentrations of metallic minerals that
can be mined at a profit
•Economic factors may change and influence a resource

Rock Cycle

• Given time and the proper conditions, any type of rock can become any other type.

Igneous Rock: “Formed by Fire”

• Form as magma cools and crystallizes

  • Rocks formed inside Earth are called plutonic or intrusive rocks

  • Rocks formed on the surface

    • Formed from lava (a material similar to magma; but without gas) (molten rock at Earth’s surface)

    • Called volcanic or extrusive rocks

From Magma to Crystalline Rock 

• Composed of ions of silicate minerals

  • Ions are arranged into orderly patterns during cooling
    (that’s minerals)

  • Crystal size is determined by the rate of cooling
    ▪Slow rate forms large crystals
    ▪Fast rate forms microscopic crystals
    ▪Very fast rate forms glass

Igneous Rocks

• identified by composition and texture

Igneous Compositions 

• Mainly composed of silicate minerals

  • Granitic (Felsic) Compositions

    • Richer in light silicates, lighter color due to Aluminum
      (Al) and Potassium (K).

  • Basaltic (Mafic) Compositions

    • Richer in dark silicates, dark color comes from Iron (Fe), Magnesium (Mg) and Calcium (Ca).

Texture 

• size, shape, and arrangement of minerals that make up rocks 

aphanitic 

• fine-grained 

  • fast rate of cooling 

Phaneritic

• coarse-grained—slow rate of cooling

Porphyritic (two crystal sizes)

• two rates of cooling

Glassy

very fast rate of cooling

Vesicular

contains holes left by gas bubbles

Pyroclastic

• fragmented; produced by consolidation of volcanic fragments (a volcano exploded!)

Common Igneous Rock

• Granitic rock

  • Felsic: composed of light-colored silicates—quartz and orthoclase

  • Common: granite, rhyolite, obsidian

• Andesitic (Intermediate) Rocks

  • Mixture of felsic and mafic compositions

  • Common: andesite, diorite

• Basaltic Rocks

  • Mafic: composed of dark minerals (dark green / black)

  • Common: basalt, gabbro

Bowen’s Reaction 

• tells us the order that mineral will crystallize from molten rock

1) olivine 

2) pyroxene 

3) amphibole 

4) biotite mica 

5) potassium feldspar 

6) muscovite mica

7) quartz 

Sedimentary Rock

• form from sediment (weathered/broken down material

• about 75% of all rock outcrops on the continents (75% out of earth surface is sedimentary rock)

• used to reconstruct much of Earth’s history

  • clues to past environment

  • provide information about sediment transport

  • rock often contain fossils

Detrital 

• formed by other rocks 

• solid particles from weathering 

• classified by particle size and shape 

  • common: conglomerate, breccia, sandstone, siltstone, shale 

Weathering (physical) [mechanical]

• big rocks are broken into small rocks

• taking it and breaking it up

• ice wedging- water gets into cracks and freezes

• heat and cooling

  • sandblasting

  • rock falls

  • moving water

Weathering (chemical)

• changes the rock composition or dissolves the rock

• water

• reaction with acids- dissolves rock and changes composition

• oxidation

weathering

• works on the outside of rocks and works faster on areas with more surface area

Detrital Sedimentary Rocks

mud

• clay <1/256

• silt <1/256-1/16

sand

• sand 1/16-2

gravel

• granule 2-4

• pebble 4-64

• cobble 64-256

• boulder >256

all in millimeters

chemical, biochemical, organic (each)

• precipitation water 

• precipitation help from life 

• precipitation stuff like coal 

chemical, biochemical, organic 

• derived from ions carried in solution to lakes and seas

• classified by composition

• common: limestone, gypsum, chert, coal

Lithification of Sediment

• lithification: processes by which sediments are transformed into sedimentary rocks

• compaction:

  • due to weight of overlying sediment 

• cementation 

  • by calcite, silica, and iron oxide 

(lith- process being turn into stone/rock)

Lithification

Compaction 

Cementation 

Crystallization (precipitation)

• turning into rock 

• squeezing together 

• glues pieces together 

  • calcite

  • silica

  • rust

• evaporation of water leaving salt crystals precipitation of cave deposits

Feature of Sedimentary Rocks

• strata, or beds (most characteristic)

  • accumulated layers of sediments over time

  • record past environments

• fossils

  • traces or remains of prehistoric life

  • are the most important inclusions

  • help determine past environments

  • used as time indicators

  • used for matching rocks from different places