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An aggregate of minerals.  Minerals are the building blocks that make up rocks.

Naturally occurring, inorganic solid that possesses a definite chemical structures which gives it a unique set of physical properties.

The basic building blocks of minerals.  Elements are composed of atoms.

Atom: smallest particle of matter that still retains the characteristics.

   →Compounds are formed when atoms bond   together with other atoms.

    →Some minerals consist of a single element like sulfer while others are compounds consisting of combinations of elements like quartz (Si O₂)

Crystal Form

Luster

Color

Streak

Hardness

Cleavage

Fracture

Specific Gravity

The external expression of a mineral's internal orderly arrangement of atoms.

Example: Some minerals like salt and pyrite tned to form crystals which look like cubest while others like quartz form six-sided (hexagonal) crystals.

The appearance or quality of light reflected from the surface of a mineral.

Example: Minerals which have the appearance of metals, regrdless of color are said to have metallic luster.

Most obvious but also the most unreliable diagnostic property.

Example: Quartz can be clear, pink, purple, mulky white, or even brown to black.

10    Diamond

9      Corundum

8      Topaz

7      Quartz

6      Potassium Feldspar, Orthoclase

5.5   Glass, pocket knife 

5      Apatite

4      Fluorite

3.5   Copper Penny

3      Calcite

2.5   Fingernail

2      Gypsum

1      Talc

The tendency of a mineral to cleave, or break, along planes of weak bonding.  If the break is very flat and mooth, the mineral "cleaves" or separates alog planes of atomic weakness.  Cleavage may be in one to six different directions.

A comparison of the weight of a mineral to an equivalent volume of water.

Example: Galena (lead one) has a specific gravity of 7.5, Gold - 20, and Quartz - 2.65.

The most common mineral group. 

Pure silicate contains only Silicon (Si) and Oxygen (O) ie Quartz.

Others contain one or more additional elements.

Basic Building block for all silicates.

Four Oxgen atoms surrounding one silicon.

1. Igneous Rocks

2. Sedimentary Rocks

3. Metamorphic Rocks

Rocks which form as magma cools and crystallizes, aka rocks formed by the crystallization of molten magma.

At or above ground, volcanic.

Lava: molten rock that has lost

most of its gaseous component.

The formation and growth of crystalline solid from a liquid or gas. 

In this case, magma to solid rocks or minerals.

1. Crystal Formation is not random

2. Not all the molten material in magma solidifies at the same time.

3. The rate of cooling strongly influences crystal size.

Slow cooling = large crystals

Fast cooling = small crystals

Texture

Fine grained

Extrusive - cooled quickly (min. - hrs. - days)

Nearly all of the grainst making up this rock are too small to be seen by the unaided eye.

Examples: Basalt and Rhyolite

Intrusive - cooled slowly (yrs - thousands of yrs)

The mineral grains are a mass of intergrown crystals that are roughly equal in size and are large enough to be seen with the unaided eye.

Examples: Granite, diorite, and andesite.

These rocks were cooled very rapidly, possibly in a process known as quenching.  As the term glassy implies, these rocks have a vitreous appearance.

This texture is porous (lots of holes) and is the result of glass bubbles being trapped

in the cooling lava.

Examples: Scoria, pumice, and vesicular basalt

1. The chemical composition of the magma from which it crystallizes. May be very different for eruptions from the same volcano.

2. N.L. Bowen and Bowen's Reation series - which si the crystallization sequence for minerals and rocks based on the temperature and pressure at which they solidify within the cooling process.

Crystallize at the highest temperatures.

Do not have any feldspars present.

Iron and magnesium are at the highest concentrations in ultramafic rocks.

Olivine is one of the common minerals

 in these igneous rocks, giving many

 ultramafic rocks a green color. 

Examples: Peridotite, kimberlite, and limburgite.

Mafic

(Basaltic)

Contain calcium feldspars such as anorthite and labradorite.  Both of these feldspars are dark colored ad the labradorite has a bluish-green iridescent appearance.

Olivine can also be found in these rocks as well as other minerals rich in iron and magnesium.

Examples: Basalt and Gabbro

Intermediate

(Andesitic)

Albite, the light colored sodium feldspar is the dominant feldspar.

Most common mineral is hornblend, while some biotite may be present as well.

These rocks are often black and white or black and grey in color.

Examples: Andesite, diorite, and monzonite.

Felsic

(Granitic)

The potassium feldspar, orthoclase, is the dominant feldspar in this igneous rock type.

Most common color for felsir rocks is pink or red.

Quartz, muscovite, biotite, and mior amounts of hornblende are common accessory minerals.

Amounts of iron and magnesium are very low.

Examples: Granite, rhyolite, and syenite.

Composed of volcanic glass.

Examples: Obsidian, pumice, and scoria.

1. Weathering - the disintegration and decomposition of rock at or near the surface.

    → Chemical, physical/mechanical, biological, etc.

2. Transport - movement of sediment downslope or downgradient.

    → Gravity, water, wind, ice.

3. Decomposition

4. Lithification

    → Compaction

    → Cementation

Example - Coal formation

Peat - Lignite - Ituminous - Anthracite

Cementing materials carried in solution by water.

Most common: Calcite, silica, iron oxide.

Calcite - fizzes

1. Layered and layers are called strata or beds.

    → Thin (mm) to thick (many meters)

    → Bedding planes: separate strata, flat surfaces

        along which rocks tend to break or separate.

2. Size of Particles

    → Molecular (chemical) to large clasts (meters)

        in detrital.

3. Fossils - traces or remains of prehistoric life

Detrital or Clastic Sedimentary Rocks

Originated as solid particles from

weathered rocks (like igneous). 

Examples: Sandstone, shales, conglomorates.

Chemical Sedimentary Rocks

1. 75% of rocks at the surface are sedimentary in origin even though they make up only 5% of Earth's volume.

2. Reconstruction of Earth History

    →Past Environment

    →Methods, distance, and magnitude of sediment

       transport.

    →Mineral Composition of sediment

3. Economic

    →Coal, oil, Natural gas

    → Iron, aluminum, manganese, fertilizer, sand

       and gravel, building materials, sources of

       fresh water.

Metamorphism - change form.

Rocks formed by the alteration of pre-exsisting rock deep within Earth (but still in a solid state) by heat, pressure, and/or chemically active fluids.

Heat

Pressure

Chemically Active Fluids

Most important - provides energy to drive chemical reactions that recrystallize minerals.

Increases with depth.

General Metamorphic Changes

1. Density Increases

2. Larger Crystals form

3. Preferred orientation of crystals - foliation

    → Example: Granite to Gneisis

4. Non foliated - no preferred orientation, just

    increase in crystal size.

    → Example: Limestone to Marble

Metamorphism can happen to ____1____.

It occurs when a rock is _____2_____. 

Most often occurs during ____3____.

1. Any rock.

2. subjected to conditions unlike those in

which it originally formed.  As a result, it

becomes unstable and gradually changes

until it reaches a new state of equilibrium. 

3. Mountain Building

Primary Factors Influencing

 Volcanic Eruption Severity

1. Magma Viscosity

2. Amount of dissolved gases

3. Temperature

4. Mineral Composition

5. Dissolved gases

Hotter means less viscious.

Cooler means more viscious.

Obviously.

Mineral/Chemical Composition & Eruption Severity

More silica rich = more viscous

Basaltic - hotter, less silica = less viscous

Graniti - ooler, more silica = more viscous

Related to water vapor and carbon dioxide.

Less viscous lava allows gases to bubble out.

More viscous lava may allow pressure to build.

Lava Flows

Gases

Tephra/Pyroclastics

Pahoehoe vs. aa

Pahoehoe: lava flow with a smooth-to-ropey surface

aa: lava flow that has a jagged, blocky surface

1 to 5% of total weight

Water vapor (benign), fluorine,

 nitrogen, sulfer, chlorine, hydrogen,

argon, and carbon dioxide (deadly)

Volcanic Ash

 Cinders

Lapilli

Welded tuff

Blocks and Bombs (>2.5")

Volcanic

Ash:

Cinders:

Lapilli:

Ash: Volcanic fragments the size of dust particles

Cinders: a fragment of volcanic ejecta from 0.5 to 2.5 cm in diameter

Lapilli: similar to ash and cinders, but larger - 2.5 to 6 cm in diameter

Date that Mount St. Helen erupted:

Mount St. Helen's VEI:

May 18, 1980

4

Values range from 0-8.

Depends on:

Volume of material ejected

Height of material ejected

Duration of eruption

Potential explositivity increases with time.

____ Historic VEI 5 Eruptions.

Most violent eruptions - _______.

19

Caldera Eruptions

Volcanic Hazards

Mount Shasta is like Mount St. Helen but ________.

Ash falls

Ash flows

Mud flows

Volcanic Landslides

Volcanic Tsunamis

Lava Flows

Volcanic Gases

BIGGER hills at bottom after landslide.

An itrusive igneous rock body with a surface exposure greater than 100 square km

Idaho Batholith > 41,000 sq. km

Stocks - are similar but smaller intrusive bodies (<10 square km)

Similar to sills because they form when magma is intruded between sedimentary layers in a near-surface environment.

More viscous.  Less fluid magma collects as a lens-shaped mass that arches the overlying strata upward.  Occasionally an be detected.

Sheet-like Igneous Rock bodies

produced when magma is injected into

 fractures that cut across rok layers.

Usually harder and more resistant than surrounding rocks and may result in fence-like appearance.

Heat - increase with depth

    → At 100 km it is about 1200 to 1400°C

Pressure - also increases with depth

    → Increased pressure raises melting points

    → Decompression melting

Water - causes rock to melt at lower temperatures.

Elastic rebound =

the sudden release of stored strain in rocks that result in movement along a fault.

Foreshocks

Aftershocks

Small Earthquake or tremor which may occur before a major Earthquake.

Small Earthquake or tremor which occur after a major Earthquake which result from minor adjustments in the affected rock strata.

Focus: zone within the earth where rock displacement produces an Earthquake

Epicenter: the location on Earth's surface directly above the focus

Seismology, Seismographs,

and Seismograms, oh my!

Seismology: the study of Earthquakes

Seismographs: instruments which record earthquake waves

Seismograms: a trace or record of earthquake waves measured with a seismographs

Surface waves - travel along the earth's outer layer

Body waves - travel through the earth's interior

Primary: push/pull waves.  Compress and expand the rock material which they travel through.  Temporarily change volume of rocks.

Secondary: shake particles of rock in a direction perpendicular to the direction of movement. Temporarily change the shape of rocks.

Distance from seismograph

    → Difference between the arrival times of the

        first P-wave and first S-wave.

Location

    → Plot of circles with radius equivalent to the

        travel time distance for three sets....

Richter Scale

Modified Mercalli Scale

Body Wave Magnitude

Surface Wave Magnitude

Maximum Acceleration

Duration

Body Wave Magnitude

Accelerometers - measurements compared to g.

g= 980 cm/sec²

1. Amplitude

2. Duration

3. Nature of the material upon which a structure

    rests

4. Design of the structures

Other considerations: Distance from epicenter, foreshocks, and aftershocks, and if it is a coastal location (tsunami)