Solar fog, primitive Earth, differentiated Earth, developed Earth, modern Earth
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Which layer is the only one that is liquid in the Earth?
outer core
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Why is the inner core solid, despite the temperature being high enough to keep the minerals liquid?
Immense pressure
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What is the most likely cause of the Earth’s magnetic field?
The circulation of molten iron and nickel in the outer core (convection current)
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What are the three types of tectonic plate boundaries?
Convergent, divergent, transform
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What two types of convergent boundary movements are there? (when two tectonic plates move toward each other)
subduction and collision
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What is subduction?
When plates of different densities converge, the higher-density plate is pushed beneath the more buoyant plate, and descends into the mantle (forms a trench, melts into magma)
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What’s typical for collision zones of tectonic plates?
Tall, non-volcanic mountains and a broad zone of frequent earthquakes
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What are the two types of divergent boundaries?
continental rift zones and mid-ocean ridges
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What is a hot spot?
An area in the litospheric plate where molton magma breaks through (creating mountains/volcanoes/islands)
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Main differences between oceanic and continental plates?
Oceanic plates are much denser (because of more iron) and thinner
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What are 3 direct and 4 indirect dangers of volcanoes?
1) damage to agricultural areas and infrastructure, 2) airfall (lava bombs etc.), 3) pyroclastic flow (most deadly), indirect: mud flows, avalanches, tsunamis, starvation (year without a summer)
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What is pyroclastic cloud?
A fast-moving current of hot cas and volcanic matter (flattens buildings with kinetic energy, incinerates living organisms)
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21
Five geochronologic time units
Eon, era, period, epoch, age
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Oldest rock in Austria (name, age, location)?
Dobra Gneiss, 1,83 billion, Waldviertel
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What is the epicenter of an earthquake?
The point on the surface that is directly above the hypocenter (place of first movement)
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Two main types of earthquakes
Tectonic and volcanic (third type: collapse of structures)
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What is a seismograph?
Instrument to record the motion of the ground, measures the magnitude of an earthquake (in numbers)
Fire (gas lines, heaters etc. offset by movement), liquefaction (sediments with water turn to semi-quicksand), tsunamis, landslides
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Where do the biggest earthquakes on earth occur?
Along the pacific plate, in areas of subduction and also on transform faults
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Why does subduction cause earthquakes?
Downward movement of rigid lithosphere plate under another plate
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What kind of mathematical scale is the richter scale?
logarithmic
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What is the definition of the magnitude on the Richter scale?
the maximum height of the wave in the first seismic wave 100 km from the epicenter
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What is orogeny?
Mountain building along a continental margin as the result of convergence
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Sources of Earth’s internal heat?
leftover heat from when it was formed (primordial heat), fricitonal heating from denser core material sinking to the center and heat from the decay of radioactive elements
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What is the current time period? In aeons, eras, periods and epochs
Phanerozoic, Cenozoic, Quaternary, Holocene
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What is convection?
Heat transfer in a fluid, causes movement because the region closest to the heat source gets less dense and rises
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What are the three main forms of heat transfer?
Conduction, convection, radiation
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What is conduction?
Transferring heat via direct molecular collision (higher-speed particles collide with slower-speed particles, that then speed up)
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What factors affect the density of seawater?
Salinity and temperature
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How does salinity affect water?
Makes it denser
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What’s the name of the malleable, flowing layer of the earth?
asthenosphere
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41
What is the main rock type of the continental crust?
Granite
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How does energy travel from the inner earth to the litosphere?
Convection
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What is the oceanic crust mainly made of?
Basalt
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What are Jupiter and Saturn made of?
hydrogen and helium
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What do Uranus and Neptune consist of?
Hydrogen and helium, but also frozen compounds that make a solid surface
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46
What do we call the epoch of the last ice age?
Pleistocene
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4 regional capitals in Austria formed in the epoch of the Pleistoscene (ice age)
Bregenz, Innsbruck, Klagenfurt, Salzburg
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What are the four eons that we can divide the history of the Earth in?
Hadean, Archean, Proterozoic, Phanerozoic
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Which eon are we currently in?
Phanerozoic
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How long is an eon?
At least 0,5 billion years
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What three eras can the phanerozoic eon (our current one) be divided into? These are also the three eras since complex life evolved
Paleozoic, Mesozoic, Cenozoic
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What is the current geological epoch?
Holocene (since 9700 BCE, after the last glacial period)
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What era are we living in?
Cenozoic (started with the extinction event that ended the Mesozoic era)
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What era is often called Age of the reptiles or Age of the Conifers?
Mesozoic era
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What era is also called the Age of Mammals?
Cenozoic (current)
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What geological period are we living in?
Quaternary
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Three ways to classify rocks, depending on how they were formed
Sedimentary, metamorphic, igneous
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How are sedimentary rocks formed?
From the compression of sediments that accumulate on the Earth’s surface (often have a disctinctive layering)
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What are some common sedimentary rocks?
Sandstone, limestone
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How are igneous rocks formed?
from Magma, that cools and forms rocks either under the surface or after a volcano eruption
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What are some typical igneous rocks?
Granite, obsidian, basalt
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How are metamorphic rocks formed?
Another type of rock is subjected to high heat and/or pressure, and is transformed (not melted) into a denser, more compact rock (new minerals form by rearranging or by reaction with fluids that enter)
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What are some examples of metamorphic rocks?
Gneiss, marble, schist
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What are the two types of igneous rocks?
intrusive (formed by cooling slowly under the surface of the earth) and extrusive (cooling quickly during an eruption)
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What type of igneous rock is basalt?
extrusive
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What type of igneous rock is granite?
intrusive
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What kind of soil forms on top of limestone?
Rendzina
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What kind of rock is limestone?
Sedimentary
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What kind of soil forms on top of sandstone?
Podzol
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What are the characteristics of podzol soils?
low level of moisture and nutrients (poor for agriculture)
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What kind of soil forms on top of loess?
chernozem (very good agriculture soil)
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What kind of soil forms on top of silicatic rocks such as gneiss or shale?
brown earth
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What’s the average geothermal gradient in Germany?
3 degrees per 100 m
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What 2 factors affect the sea level?
Internal fluctuations (changes in runoff from the land, melting, warmth expansion), land changes (uplift, sinking etc.)
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What are the layers of the ocean?
Surface layer, thermocline and halocline (pycnocline is a function of these), deep ocean
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What is the thermocline?
A zone of rapid temperature change in water (at least 1 degree per meter)
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What is the halocline?
A zone where there is a rapid change in salinity in water
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What is the pycnocline?
A zone where the water density increases rapidly with the depth (tends to coincide with the halocline and thermocline)
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What kind of heat transfer happens inside the solid parts of the Earth (crust)?
Conduction
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What plate boundary type is the most dangerous concerning earthquakes?
Convergent
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What are areas of exchange between the lithosphere and the asthenosphere?
Mid Oceanic Ridges and subduction zones
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How much to the major tectonic plates move per year?
Between 1,6 cm and 18 cm
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What is the zone of the ocean called where there is a rapid change of dencity?
Pycnocline
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What type of meteorite is most common?
stone (94 %)
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Where are volcanoes typically found?
At diverging (MOR) or converging (pacific ring of fire) plate boundaries, usually underwater, as well as on hotspots
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What are the three main types of magma?
basaltic, andesitic, rhyolitic
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What are the darker areas of the moon?
Basalt (solid lava)
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Differences between basalt and granite
Basalt is extrusive, 50 % quartz (vs 70 % in granite), high density, high crystallisation temperature, dark colour because of specific minerals
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How is andesitic magma formed?
Melting ocean plate due to subduction (basalt, creates very gaseous magma)
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How is rhyolitic magma formed?
By suduction of oceanic lithosphere under a continental plate (usually rich in water and has CO2)
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How is basaltic magma formed?
Comes from the mantle, forms oceanic crust
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What’s the longest mountain chain on the surface of the Earth?
The Mid Ocean Ridge
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What’s the Mercalli scale?
Measures intensity of earthquakes based on observed effects, levels 1-10 (e.g. 2: felt only by few persons at rest, 10: masonry structures destroyed)
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What is the magnitude vs intensity of an earthquake?
Magnitude is size of wave, intensity is felt effects
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When did the Quaternary period start?
2,58 million years ago
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When did the Holocene epoch start?
11,600 years ago (last glacial period)
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When did the Cenozoic era start?
66 million years ago (with the cretaceous-paleogene extinction event)
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What is the light-colored rock that makes up the crust of the moon?
Anorthosite (consists mainly of plagioclase feldspar)
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What structures can silicates have?
single chain, double chain, isolated silicon tetrahedra, sheet, 3D/framework
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Imagining the history of Earth as one year, what month did mammals evolve?
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Flashcard (41)