Units 1-5: Geomorphology Flashcards
What is gemorphology?
Study of the form and structure of the earth and the process that shape them
The crust (which is thickest under the continents and thinnest under the ocean) is split into what?
Tectonic plates
What is the Moho Discontinuity?
The boundary between the crust and the mantle
What is the asthenosphere?
the upper mantle of the earth
What is NiFe? What is SiAl? What is SiMa?
Nickel and Iron (core)
Silicon and Aluminum (Continental crust)
Silicon and Magnesium (Oceanic crust)
How is sedimentary rock formed?
Formed from sediments deposited by wind, water or ice. They are compacted together forming strata
How is metamorphic rock formed?
It is formed when igneous or sedimentary rock undergoes a change cause by heat or pressure
How is igneous rock formed?
It is formed when molten rock called magma rises through the crust, cools then crystalizes. The slower it cools the larger the crystals that form
Explain resistance in rocks.
Some rocks are more resistance than others meaning they erode more slowly and have a steeper slope, eg sandstone. (Shale is soft)
Explain permeability. (opposite is impermeable rock)
The ability of a rock to let water pass through. Water can pass through tiny spaces between cracks or sediments in a rock
What is the continental drift theory?
Theory suggested by Alfred Wegener that tectonic plates move and are not fixed. This was later expanded into the Plate Tectonic theory.
Fill in the blanks:
200 million years ago there was a super continent called _____ which later broke apart into ____ and ____. These then broke into the continents we know today.
Pangea
Laurasia
Gondwanaland
6 pieces of evidence of plate tectonics
- Coastlines (fit together)
- Fossils (same species that cant swim was found on multiple continents)
- Plants (plant life is very similar on different continents)
- Rocks (mountain ranges with similar rock formations form on different continents)
- Deposits (coal deposits formed from the same thing are found on different continents)
- Glacial deposits (Brazil and West Africa have the same glacial deposits meaning they were covered in the same ice sheet)
What causes the plates to move?
Convectional currents, they are formed from heat in the mantle
What is the cause of faulting?
Great pressures causes rocks to bend then fracture and shift
What is a tensile force? (Normal fault)
moving away from each other. One side falls down
What is a compression force? (Reverse fault)
Moving towards each other. One side is pushed up
What are lateral/horizontal forces? (Strike slip fault)
(eg San Andreas fault) Move past each other
How is a rift valley formed? OR graben
caused by normal fault or tensile forces
How is a block mountain formed? OR horst
caused by reverse fault or compression forces
Describe a horst.
roof with a floor on either side
Describe a graben.
floor with a roof on either side
Labels in normal / reverse faults
Exposed rock - fault scarp
Rock pushed up/falling down - roof/hanging wall
Other piece of rock - floor / footwall
Why are rift valleys important?
Helps with farming, attracts tourists, the steep slopes help to generate HEP,
Focus definition
The place where earthquakes start (underground)
Epicenter definition
The place directly above the focus (above ground)
Seismic wave definition
Movement of ground traveling through the earths surface in the form of a wave
Seismograph definition
Instrument used to measure seismic waves
Richter scale definition
Scale used to compare strengths of earthquakes
Effect tsunamis has on people
Death, loss of resources and possessions, land is eroded and places can get cut off
Why are earthquakes less devastating in developed countries?
They have early warning systems and technology that can predict them, buildings are more resistant to them, emergency services are better and more equipped, people are more educated about how to deal with these situations
How to reduce impact of earthquakes?
Identify high risk areas and avoid them, better prepare emergency services, build dams at fault lines to absorb shock, strengthen infrastructure, educate people on these situations and crises
How to predict an earthquake?
Tremors can occur before earthquake, animal behavior can help predict it, instruments can record signs and help predict it in the future
Active volcano definition
Volcano that still erupt (have erupted in the last 10000 years)
Dormant volcano definition
Volcano that show no sign of activity, but are likely to erupt again
Extinct volcano definition
Volcano that isn’t expected to erupt again
Features of a volcano
Magma chamber —-> pipe / fissures —-> Volcanic cone —-> crater —-> lava flows / rocks / lava bombs / gases
What is a shield volcano
It has gaseous, runny, hot lava. It gives off few/no explosions (Kilauea)
What is a cinder cone volcano
It has lots of glassy lava, ash and solid material. It is the simplest volcano with smallest cone and the steepest slope. (Monte Nuovo)
What is a composite volcano (stratovolcano )
It ha slots of layers of ash and lava surrounding it and has fairly steep slopes. The eruptions are normally explosive (Mount Vesuvius)
How do volcanoes affect people positively?
- Some volcanoes areas become tourist attractions (income)
- There could be diamonds in the volcanic pipes
- Volcanic ash can act as a fertilizer in tropical regions and rocks can break down to form fertile soil
- Hot springs are good for tourist attractions
- Underground water in these areas is hot and good for generating heat or electricity
How do volcanoes affect people negatively?
- Water supply could be polluted
- Ash and fumes in the air is dangerous for health
- Buildings can collapse from the weight of the ash
- Changes river systems / creates dams
- Burns trees, house etc.
- Ash blocks the sun
- Ash and solidifying lava is dangerous
- Planes cannot fly through ash
How can you predict volcanic explosions?
Seismographs can be used to measure small earthquakes (These can trigger volcanic eruptions), ground temperatures will rise as the magma moves, gas and steam are given off before it erupts, the sides of the volcano swell and bulge which can be measured with a tiltmeter
How can you be prepared for a volcano?
Set up a monitoring system or early warning system, make sure emergency and medical services are ready to evacuate, prepare and emergency plan, organize emergency supplies such as water or food
Examples of the deadliest volcanic eruptions. (Know at least 2)
- Mnt Vesuvius, Italy in 79AD, 3 360 casualties caused by pyroclastic flow
- Laki, Iceland in 1783, 9 000 casualties caused by starvation
- Kelut, Indonesia in 1586, 10 000 casualties
- Uzen, Japan in 1792, 15 000 casualties caused by volcano collapse and tsunami
- Nevada del Ruiz, Colambia in 1985, 25 000 casualties caused by mudflow
- Mont Pelee, Martinique in 1902, 30 000 casualties caused by pyroclastic flow
- Krakatau, Indonesia in 1833, 36 000 casualties caused by tsunami
- Tambora, Indonesia in 1815, 92 000 casualties caused by starvation
