Earth and atmosphere flash cards

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What are the four layers that make up the earth?
Atmosphere, Crust, Mantle and Core.
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Describe the atmosphere
A layer of gases (100 Km thick)
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Describe the crust
Relatively thin, layer of rock, contains all the minerals and rocks. 5-70 Km thick
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Describe the mantle
The mantle is a thick layer of rock (2900 Km thick) semi molten moves very slowly 1000 degreesC
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Describe the core
Made up of an outer core and an inner core. Made of molten iron but there is a solid nickel inner core. Half the thickness of earth. (3400 Km radius)
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What is the lithosphere?
The outer part of the earth includes the crust and upper mantle
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What are Tectonic plates?
The lithosphere is divided into these and each plates move at a speed of a few cm a year.
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What causes the movement of tectonic plates?
Convection currents in the mantle caused by the heat produced from radioactive decay in the core.
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What are earthquackes?
Shaking of the earth that occurs at plate boundaries as the plates move past, over, under or apart from each other friction causes sudden jerks.
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Volcanoes?
When plate boundaries move and magma from the mantle escapes.
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Warning signs before an earthquake include:
increased seismic activity (shocks that can be detected by scientific instruments). Water levels in wells fall, some animals act strangely.
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Volcanic eruptions can be predicted by:
Knowledge of the areas they occur. Definite warning signs e.g. increasing temp, rising ground level, more sulfur dioxide emmited.
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Why can't scientists predict major earthquakes or volcanic eruptions exactly?
It is difficult to predict when there will be enough pressure for plates to slide or for magma to burst through the crust. Can't issue false warnings. Instruments can't measure through crust.
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Describe the shrinking apples(custard) theory
Theory suggests that while the hot young Earth cooled the crust shrank and winkled forming mountains.
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Describe the theory of continental drift.
The continents were moving around and were once joined together in a big land mass and slowly drifted apart and are still drifting.
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Evidence for Wegner's theory includes:
The continents fit together, west coast of Africa and east coast of South America have identical rock layers. The coasts have same types of plant and anmal fossils. Some are found only in these parts of the world and could not swim or fly.
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Why weren't Wegner's ideas accepted?
He had no explanation for how the continents moved. He was a meteorologist not a geologist. His ideas were given no credit among geologists.
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Why were the accepted in the 1960s?
The Atlantic ocean floor was studied and the Mid-Atlantic Ridge found. Rock in ocean younger than in continents. Convection currents discovered, tectonic plates.
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What is the trend in thickness of the Atmosphere?
The further away from the earth the atmosphere gets thinner there are fewer gas particles.
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Composition of Air?
78% Nitrogen, 21% Oxygen, 0.9% Argon, 0.04% Carbon dioxide, traces of other gases.
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Uses of these gases
Nitrogen is unreactive used in food packaging microbes can't respire. Oxygen used for breathing, Argon in light bulbs.
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What is used to separate the gases in the air?
Fractional distillation- air is cooled and to liquid and as it warms up substances boil at different temps collected separately.
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Describe the early atmosphere.
Predicted that it is carbon dioxide, water vapour, ammonia and methane.
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Where did current gases come from?
Early atmosphere formed of volcanic activity. When the Earth cooled down water vapour condensed formed oceans. Oxygen came from photosynthesis CO2 reduced from photosynthesis. O2 reacted with ammonia and methane. N2 from volcanoes, comets, bacteria.
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Describe the Miller Urey experiment
This shows how amino acids wer formed from methane, ammonia and hydrogen and water when struck by lightning. Forms a primordial soup.
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Why have CO2 levels changed?
Fell from high levels in early atmosphere to low levels remained for 200 million years. Levels are now increasing (human activities) global warming.
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What removed CO2 from early atmosphere?
About half dissolved into the oceans reacted with substances in sea water formed CaCO3 sank to the bottom. Also formed HCaCO3 made shells. Some used for p/syn, sediment made fossil fuels.
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Other cards in this set

Card 2

Front

Describe the atmosphere

Back

A layer of gases (100 Km thick)

Card 3

Front

Describe the crust

Back

Preview of the front of card 3

Card 4

Front

Describe the mantle

Back

Preview of the front of card 4

Card 5

Front

Describe the core

Back

Preview of the front of card 5
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