GEO 1303 Lecture Exam 2

Weathering

Erosion

Physical weathering

Reduces solid rock to small fragments without altering the chemical composition of rocks and minerals (Ex- gravel, sand, salt, clay sized particles)

Chemical weathering

substances derived from solution by inorganic or biochemical processes (Ex- clay minerals and ions, compounds and solution)

Regolith formation on Moon

Regolith formation on Mars

Regolith formation on Earth

Soil degradation

Earthquakes Causes

• Movement along faults

• Volcanic eruptions

• Landsides

• Explosions

Seismic waves

They cause the most of the damage and shaking people feel
during an earthquake

• Body waves travel through Earth. P wave fastest a first wave, S-wave shears material and second wave

• Surface waves trave; along or just below the surface

Measuring earthquakes

• Intensity ( qualitative)- measures the kind of damage

• Magnitude (quantitative)- measures the amount of engergy that is released

Destruction from earthquakes

• Ground shaking

• Liquefaction (water-saturated clays becomes fluid during ground shaking)- ground is no longer stable and buildings fall

• Fire-natural gas and water lines break

• Tsunami- seafloor earthquakes generate deadly waves

• Ground failure-landslides and rockslides

• Human death

Earth’s interior

Volcanism in the solar system

• Jupiter moon Io is the most volcanically active body in the solar system

• Mars Volcano Olympus Mons is the tallest in the solar system

• Venus has volcanoes and flood basalt

• Mercury has widespread flood basalts

• the dark parts of the moon are flood basalts

Features of Volcanoes

Parts of Volcanoes

• Vent- where magma and other volcanic products erupt onto the surface

• Crater- hole at the hop of the volcano

• Caldera- circular depression formed from the collapse of rock above an empty magma chamber (example-Crater Lake)

• Fissures- linear cracks along the side of the volcano that magma can also erupt from

Volcanic gases

• Mostly water vapor

• Also contains CO2, SO2, HS, N2

• Very small amounts of C), Hydrogen, and chlorine

Flood basalts

involve HUGE volumes of magma and represent the largest basalt eruptions on Earth. (example-Columbia Plateau)

Volcanic hazards

Basaltic

• Lava Flow

• Volcanic ash

• Lava/fire fountain

• Lahar

• Pyroclastic flow

Locations of volcanoes

Most are found at plate boundaries (60% are at the ring of fire)

• Divergent plates are mostly mafic sheild volcanoes with pillow basalts

• Convergent plates and subduction caused the ring of fire. They form intermediate or felsic volcanoes

• Intraplate (hot spots) form mafic shields (Hawaii)

Depositional environments

A geographic setting where sediment
is accumulating. Determines the nature of the sediment that accumulates

Depositional environments resulting rock types

Detrital sediments Formation

• Conglomerate-forms in water

• Breccia- forms with little water

Detrital sediments classification

• Conglomerate- well rounded pebble sized clast. Mix of sand slit or clay

• Breccia- angular pebble sized clasts with sand silt or clay

• Sandstone-sand sized grains, layers

• Shale- very fine grained clay particles that breaks in chips

Detrital sediments types

Gravel, Boulder, Cobble, Pebble, sand, mud, slilt, and clay

Chemical sedimentary rocks classification

• Evaporites- rock salt and rock gypsum, Chemcial sediments formed by precipitation of a mineral during the evaporation of water. Forms in dired up lakebed

• Carbonate- limstone and dolostone, primarily containing the carbonate ion such, forms when magnesiu replaces some calcium in limstone. Forms in calm saltwater

• Coal- composed of altered land plant remains

• Chert- flint and jasper, forms in deep marine, microcrystalline quartz

Sedimentary facies

Sediment or sedimentary rocks that are recognizably
different from adjacent sediment or sedimentary rocks
and are deposited in a different depositional
environment. Sea levels either increase or decrease to create these

Bedding types

• Cross bedding- perserves layers deposited at an angle. Sand dunes and shallow marines.

• Graded bedding- largest heavist particles settel first and then smaller particles on top

• Parallel bedding-This type of bedding typically forms in environments with relatively low energy, allowing sediments to settle uniformly and create distinct layers that run parallel to each other.

Sedimentary structures

• Currnet ripple marks- asymmetric ripple marks

• Wave formed ripple marks- symmetrical shappe ripple marks

• Mud cracks-when mud dries out and leaves cracks

• Fossils- remains and traces of ancient life

Petroleum Gas

Made from microoganism,Oil gets trapped in sandstone

Sedimentary rock resources

 Sand and gravel
 Clay
 Coal
 Limestone
 Phosphates
 Gold, uranium, and other
metals
 Salt
 Gypsum (used in drywall)
 Banded iron formations
 Petroleum (oil and
natural gas)

Metamorphism

transformation (change) of rocks without melting, usually beneath Earth's surface. Caused by heat, pressure, or fluids

Contact-high temp low pressure

Dynamic- when rocks are crushed. high pressure low temp

Regional-msot common, found at convergent plates. High temp and pressure.

Meteorite impact- ultrahigh temp, ultrahigh pressure

Metamorphic grade

Index minerals

the degree of metamorphic change a rock
has undergone, usually listed as low(small change), intermediate (medium change), or high (large amount of change)

Classification of metamorphic rocks

Foliated textures are produced
by the preferred orientation of
platy minerals, such as
muscovite, because of pressure

Nonfoliated textures do not
have preferred orientation of
minerals (minerals are
randomly oriented)

Metamorphic facies

a group of rocks containing a distinctive mineral assemblage formed under similar conditions of temperature and pressure

Metamorphic mineral and rock resources

Slate Marble Gneiss. Graphite, Talc, Garnet, Metallic ores

Shield Volcano

• Looks like Captain America’s shield sitting on the ground

• Gentle slopes

• Basalt

• Non explosive and poses little danger to humans

• Begins with a lava/fire foundation. Scoria forms a cinder/scoria cones in a few months

• low viscosity (more fluid)

Cinder/ Scoria Conde Volcano

• Steep-sloped rarely exceeding 300m high

• Mafic compositions

• Found with shield volcanoes

• Scoria and other pyroclastic materials

Composite Volcano

• Composed of layers of lava flow, pyroclasitc debris and volcanic mud flows

• Explosive and most dangerous to humans

• Volcanoes rimming the pacific ocean are mostly these types

• most have intermediate compositions

• Tephra is pyroclasitc material that ejected during eruption

• Eruption columm is tephra and gas that rises upwards into the atmoshphere

• Pyroclastic flow forms when eruption column collapses as a dense, swirling cloud of hot gases, volcanic rock and ash

• Lahar is rain and snowmelt mixing with lose ash and rock

Lava Domes

• Viscous and usually felsic or intermediate lavas are forced up through the conduits of some volcanoes

• these erupt explosively

Elastic Rebound theory

• Rocks deform

• Rocks rupture when pressure builds in rocks on either side of a fault to a level l which exceeds the rocks strength

• Rocks rebound and returns to original shape when pressure is released

Name that Feature

S-wave, can only travel through solids

Name that feature

1- Focus/hypocenter

2- Epicenter

Name that Feature

S-wave shadow zone- blocks where s waves can go because it is liquid

Name that feature

The ground becoming no longer stable because of liquefaction

Name that feature

P-wave, travels through solids and liquids, fastest wave

Name that feature

Effects of a tsunami

Name that feature

P-wave shadow zone- the core diffracted the p-wave some little make it to the surface in this area

What happened in Pompeii in the year 79?

Vesuvius covered the city in pyroclastic flow

Which is NOT a type of physical weathering

Hydrolysis

Which is the term for the spot on the surface directly above where the earthquake occurs?

Epicenter

Which of the following is involved in regolith formation on mars?

• Meteorite impact

• water

• wind

Which of the below volcano types would you expect to form fro the highest viscosity magma?

Composite

Which of the following is the most common and destructive earthquake hazard?

Ground shaking

Which mineral on Bowne’s reaction series is most resistant to weathering?

Quartz

Volcanoes found at subduction zones are mostly _____; volcanoes found at hot spots are _____.

Composite, shield