Minerals and Structure of the Earth Flashcards
Name and describe the four stages of the formation and development of the Earth.
- From Solar fog -> primitive earth
• accumulation of particles through gravitation
Formation of a main celestial body that accumulates smaller particles through gravitation because of
- heat increase because of converted kinetic energy after collision
- compression and rising gravity
- from primitive earth to differentiated Earth (formation of core and mantle)
• heavy elements move to the centre through gravity
-> causer further heating
• creation of a magma ocean
- > metals sink
- > silicates rise
- from differentiated Earth to developed earth
= mantle-crust-fractionation ( Zerlegung eines Stoffgemisches)
• the primitive mantle melted partially and created basalt magma. - from developed earth to modern earth
= Inter-crustal-differentiation
• partial melting of lower crust
• granitic melts rise into upper crust
Label the following diagram.
bild kann ich nicht einfüge
Name and describe the three basic types of rocks.
- igneous rock (magmatisch)
• forms when magma from the Earth’s interior slowly cools
- > intrusive (störend, aufdringlich) igneous rocks
- this can form a crystalline structure
• when magma cools rapidly
- > volcanic rock (extrusive igneous rock) forms
- Due to the rapid cooling, little or no crystals are formed (like basalt).
- metamorphic rock
• when igneous or sedimentary rocks change due to pressure or temperature - sedimentary rock
• is formed by:
- Solidification of sediments (verfestigung)
- can arise from organic residues (limestone)
- can arise from cementation of other rocks
Which factor determines the type of soil that forms in a certain region?
depend on
• the original rocks that were in the area from which they form
- limestone –> rendzina (flachgründiger boden)
- sandstone –> podzona
- loess –> chernozem (Schwarzerde)
- gneiss/shale (gneis und schiefer) –> brown earth
Name the five structures silicates can have.
- isolated tetrahedra
- chain of tetrahedra
- double chain of tetrahedra
- sheet of tetrahedra
- complex three-dimensional network
Name five differences between basalt and granite.
• both consist of silicon-oxide and magnesium-oxide.
- basalt contains more magnesium-oxide
- granite contains more silicon-oxide.
- granite is of lighter colour
- basalt is rather dark
- basalt is high density
- granite has low density
- granite is formed on the surface of the Earth
- while basalt forms in the interior.
- basalt is mainly found in ocean floor
- granite is mainly found on land masses
Which process creates the magnetic field of the Earth? How can the magnetic field be used to reconstruct the formation of the ocean floor?
• is caused by convection currents in the outer core
- Because the magnetic field reverses over time, the sea floor can be dated
Certain atoms (e.g. atoms of magnetite) are aligned towards the magnetic north pole during rock formation and remain in that position after the rock has cooled.
This creates a symmetrical pattern on either side of a MOR. With lots of data and comparisons, this pattern can be used to date seafloor material.
Which two factors influence the sea-level?
- eustatic oscillations
• internal changes (in the ocean) - variation of surrounding land masses
- subsidence (Senkung), uplift, artificial removal of ground water, etc.
Which factors influence the density of sea water and which three zones are distinguished (herausragend, bedeutend) in the ocean?
Salinity and temperature
- surface layer
- thermocline, halocline, pycnocline
- deep zone
Which are the two main sources of heat on Earth?
- Exogenous source: the sun.
- > pushes surface processes
- glaciers
- desserts - Endogenous source:
- volcanism
- mountain building
-> from Interior of the earth:
- primordial heat
= a leftover from the formation of the earth and its core. - gravitational contraction causes the Earth to decrease in volume and become denser
- > increasing the temperature in the process.
- radioactive decay of isotopes in mantle and crust releases thermal energy.
How does heat flow in the geosphere?
convection = heat transport through movements
-> energy transport from earth’s inner core to the lithosphere
conduction = (heat transport without movement)
-> energy transport trough the lithosphere to the earth surface
• in the plastic parts of the geosphere
- through Convection (outer core, mantle, asthenosphere) the heat from the core gets transported to the surface.
Convection inside the mantle is one of three driving forces causing tectonic movement and it causes the magnetic field of Earth.
• In the solid parts (lithosphere, crust)
- conduction takes place.
Explain the terms endogenous and exogenous.
endogenous dynamcs = relief- elevating process (Entlastungs-erhöhend) -> caused by internal energy • Tectonics • magnetism • metamorphism • composition and movements of Earth.
exogenous dynamics
= relief- decreasing process (entlastungsmindernd)
-> source is the sun.
- weathering
- water cycle
- climate zones
- oceans
- sediments
Name and describe the three types of plate boundaries.
• Divergent:
- plates move apart from each other
- > new lithosphere is formed
• Transform:
plates slide past each other. (earthquake)
• Convergent:
plates move towards each other
-> the lithosphere is subducted into the mantle (subduction, if one of the plates is dense enough)
or
-> the plates collide and their edges are compressed, folded and uplifted
Name the 7 most important tectonic plates and locate them on the map.
bild nicht einfügen
What is a mid-ocean-ridge?
An underwater mountain system formed by plate tectonics.
• consists of mountains chains
• is the result of seafloor-spreading and is found at divergent (auseinandergehend) plate boundaries
- > lithosphere gets thinner and magma can errupt
- > mountains are formed
As they are located on plate boundaries, these zones show a lot of geological activity in the form of volcanism and seismicity. (island)
Name the three different types of magma.
- ANDESITIC MAGMA
- consists of molten plate material
- the subducted plate consists of basalt and water, which results in very gaseous magma. - BASALTIC MAGMA
- comes from the mantle
- can break through the crust due to high temperatures. - RHYOLITES
- formed in the continental crust
- usually rich in water and containing CO2.
Where are volcanoes typically found?
- where tectonic plates are diverging
- Sometimes volcanoes also form in the middle of the earth’s plates, on hotspots.
Hotspots are hot areas in the Earth’s interior from which magma erupts. This is how Hawaii was born.
Name the direct and indirect hazards (gefahren) posed by volcanic eruptions.
- direct
• ash fall
• pyroclastic flow (explosion)
• lava flow (effusion)
2. indirect • lahars (violent type of mud flow) • tsunamis • earthquakes • landslides
