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38 Cards in this Set
- Front
- Back
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Where is the Moho Boundary found |
In between the Crust and the mantle |
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How thick is the oceanic crust |
5-10 km thick |
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What is the Asthenosphere |
The inner layer of the mantle, between 100-300km, it is viscous and flows due to convection currents |
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How thick is the mantle |
2900 km thick |
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What state is the mantle |
Semi-Molten |
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What fossil is found across South America, Africa, India, Australia and Antarctica |
The Glossiperitis fossil (plant) |
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Characteristics of the Mantle |
Thickness: 2,900km Density: At Moho - 3.3kg/m^3 At Core - 5.6kg/m^3 Mineral Composition: Rich in magnesium and iron |
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Characteristics of crust |
Thickness: Continental crust: mean 35km, min 30 and max 70 Oceanic crust: 5-10km Density: continental crust - 2.6 Oceanic crust: 30 Mineral Composition: Continental: mainly granitic, silicon and magnesium Oceanic: mainly basaltic, silicon and magnesium |
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What is the difference between the lithosphere and the asthenosphere |
Lithosphere is cool, rigid and brittle Asthenosphere is hot, weak and plastic |
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How do convection currents move plates |
Vast amounts of heat from mantle melt the asthenosphere in to a plastic like texture which flows slowly moving tectonic plates |
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Geological evidence for continental drift |
Fits of continents like South America and Africa Rock Sequences and Mountain chains ( Canada and Scotland) |
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What is paleomagnetism |
Traces of change in the Earths magnetic field in the alignment of magnetic minerals in sedimentary and igneous rocks |
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What is sea floor spreading and evidence for it |
Sea floor spreading is the lateral movement of new oceanic crust away from a mid ocean ridge, or a constructive plate, evidence for this is paleomagnetism |
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How was the map of tectonic plates discovered through seismic data |
In 1960s; nuclear tests were done underground, releasing vast amounts of energy picked up by seismometers |
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What is the earths core composed of |
Iron and Nickel |
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What is the lithosphere |
A rigid layer between the crust and the asthenosphere |
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How often does the earths polarity change |
Every 400,000-500,000 years |
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What tectonic hazards happen at a convergent plate margin |
Convergent is (continental and continental) here there are very frequent high magnitude earthquakes |
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Describe Explosive volcanoes and where they occur |
A violent eruption occurring to the build up of pressure in a volcano, due to viscous magma, they occur at Convergent plate boundaries |
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describe Effusive Volcanos and where they iccur |
Gentle and free flowing, basic eruption of lava, they occur at a Divergent plate boundary |
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Viscosity |
An indication of how well a substance flows High viscosity = thick and sticky Low viscosity = Thin and Runny |
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Lava Plateau |
When basic Lava flows from many fissures, large areas can be covered by free flowing lava known as flood badalts, when formed they have a slope of 1 degree |
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Lava Plateau |
When basic Lava flows from many fissures, large areas can be covered by free flowing lava known as flood badalts, when formed they have a slope of 1 degree |
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Shield Volcano |
Feature of Effusive volcanoes Low with gently sloping sides and are formed from layers of lava |
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Lava Plateau |
Feature of Effusive volcanoes When basic Lava flows from many fissures, large areas can be covered by free flowing lava known as flood badalts, when formed they have a slope of 1 degree |
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Archipelago |
Features of Exlosive Volcanoes A group of islands closely scattered in a body of water, this means the islands were formed by volcanoes from the ocean floor |
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Archipelago |
Features of Exlosive Volcanoes A group of islands closely scattered in a body of water, this means the islands were formed by volcanoes from the ocean floor |
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Strato-Volcanoes |
Feature of explosive volcanoes Steep sided cones formed from layers of ash and acidic lava flows |
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Sill |
Features of Explosive Volcanoes A flat piece of rock formed when magma hardens in a crack in a volcano |
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Sill |
Features of Explosive Volcanoes A flat piece of rock formed when magma hardens in a crack in a volcano |
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Dyke |
Features of explosive Volcanoes Pathways of rising magma inside vertical fissures |
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Caldera |
Feature of explosive volcanoes A volcanic crater formed when the explosive eruption destroys the cone, and the magma chamber below is emptied |
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Define Hazard |
A geophysical event like a volcano become a tectonic hazard when poses a risk to people |
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Define Hazard |
A geophysical event like a volcano become a tectonic hazard when poses a risk to people |
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Define Risk |
The probability of a hazard event occurring and creating loss of life |
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Define Hazard |
A geophysical event like a volcano become a tectonic hazard when poses a risk to people |
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Define Risk |
The probability of a hazard event occurring and creating loss of life |
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Define Vulnerability |
A high risk combined with an inability of individuals and communities to cope |
