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science term 4 earth science
Terms in this set (46)
naturally occurring inorganic solids that have a regular atomic arrangement and a fixed chemical composition.
hardness, density, colour, lustre, crystal form, cleavage, streak and acid test.
3 major rocks
igneous, sedimentary and metamorphic
molten rock found above the Earth
molten rock below the Earth's surface
igneous rock types
intrusive or extrusive
intrusive igneous rock
formed inside the Earth's crust. This occurs when magma cools down down forming intrusive igneous rocks. They have larger crystals because the magma cools down slower than it would outside the Earth's crust letting the crystals have more time to develop.
extrusive igneous rock
Formed outside the Earth's crust on the Earth's surface. This occurs when lava (melted rock) is cooled down. The crystal size of these rocks are small or some don't have any because the lava cools more rapidly out side the Earth's crust not letting enough time for the crystals to develop, hence forming small or no crystals.
3 types: clastic, chemical and biological
formation: A rock made sediments which have undergone compaction and/or cementation.
processes involved: Weathering, erosion, deposition, compaction, cementation and lithification
clastic sedimentary rock
These are formed from sediments of pre-existing rocks and minerals. These sediments undergo the process of lithification and are then assigned a final classification depending on the size of the sediments and the minerals present in the sediment.
chemical sedimentary rock
These rocks form when water travelling through rock dissolves some of the minerals in the rock. These dissolved minerals are carried away and are redeposited when the water evaporates.
biological sedimentary rock
These rocks form when the remains of organisms undergo lithification.
metamorphic rock types
regional and contact
regional metamorphic rock formation
existing rock is changed when it is exposed to heat and pressure. Occurs deep in the Earth's crust.
contact metamorphic rock formation
heat from magma changes existing rock it comes into contact with
Rocks undergo changes and can change from one type to another - can be inorganic or organic is composed of minerals
layers of Earth and atmosphere we have direct contact with
hydrosphere, crust and the troposphere
All the water on Earth
-The outermost layer of the Earth -composed of sedimentary, igneous and metamorphic rock.
thinnest layer of the earth
-consists of about a dozen tectonic plates also known as lithospheric plates
The troposphere is the lowest layer of the atmosphere. This layer is where most of the weather
and clouds we observe are located.
layers of earth
upper solid part of the Earth and includes the crust and the rigid upper mantle
stationed around the Earth and the analysis of seismograms has provided the scientific community with evidence to make inferences about the Earth's interior
primary compressional waves, which travel very fast through both solid and liquid mediums.
transverse or shear waves, which travel slower than P-waves and only through solid mediums
-The dense boundary between the crust and mantle
-Nobody has ever seen this boundary; but the speed of waves traveling downward
through Earth speed up in this region because of change in rock types from less dense to more dense.
-waves travel faster through dense
consists of hot, dense,
semisolid rock and lies between the the core and the the crust
upper mantle (asthenosphere)
-Earthquake waves travel slower in liquids than in solids and there is a region of the mantle about
100-200 km below the surface where earthquake waves slow down.
-therefore it is composed of a flowing, plastic,
Below the flowing semi-solid portion of the mantle the waves speed up, suggesting the lower
(deeper) region of the mantle is more solid, stiff and rigid.
-The inner layer of the Earth
- temperature, pressure and density is very high in this region.
- outer core of the Earth is composed of molten iron because S-waves do not
travel through it
- inner core is composed of solid iron and nickel. ]
How convection cells in the asthenosphere can move lithospheric plates
-Deep within the Earth there is tremendous heat and pressure
-As the rock heats up, density decreases and the rock begins to travel through the mantle
- As the semisolid rock comes close to the rigid lithosphere, it transfers heat to the lithosphere,
- the decreased temperature results in increased density
- rock sinks back into the depths of mantle
variations. Plates move toward each other and crust is destroyed
-Plates move away from each other and new crust is formed
-Convection currents forming below in the asthenosphere drive the plates further and further apart.
Plates slide past each other
Oceanic - oceanic convergent boundaries
-Old oceanic crust is denser than new oceanic crust because it is colder
-the more dense (older) plate travels underneath the less dense younger plate via the process of subduction
-denser rock is forced deep down into the mantle, destroying the oceanic crust
-trench is formed
-As the dense rock is forced deeper within the mantle, friction, heat and pressure can melt the rock resulting in the formation of magma chambers and dykes
-Overtime, an island arc can form as the lava continually cools and solidifies
e.g.Mariana Islands in the Pacific Ocean
Oceanic - continental convergent boundaries
-Oceanic crust is more dense than continental crust
- oceanic crust subducts beneath the continental crust. - oceanic crust is forced down into the mantle forming a trench along the shore.
-As the oceanic crust is forced downward, it is being destroyed
-Deeper within the mantle increased friction, heat and pressure cause existing rock to melt forming magma chambers and intrusions
-Liquid rock is less dense than solid rock and rises forming inland volcanic arcs and mountains
e.g. formation of the Andes Mountains and volcanoes in South America
Continental - continental convergent boundaries
- the densities of the plates are very similar and subduction does not occur
- Instead, the plates collide powerfully, which buckles and pushes the crust upward
Oceanic - oceanic divergence
-forms ocean ridges: As the plates move away from each other, liquid hot magma rises up, cools and solidifies forming new rock and pushing older rock further outward on each side.
Continental - continental divergence
-forms inland rifts: continental plates slowly spread apart
-As the plates move a part magma rises up and solidifies forming new continental crust.
e.g.The Great Rift Valley in Africa
- sudden movements within the Earth's lithosphere
- detected around the Earth by seismometers
as P, S and L-waves.
-When solid rock of the lithosphere breaks or
slides past each other the stored energy is
transformed into kinetic energy
- Motion of the lithosphere results and the ground shakes slightly or sometimes greatly
-occur most at plate boundaries
locked regions of transform boundaries
-locked regions: seismic activity is less frequent and energy is stored for longer periods of time.
-When energy is finally released, very powerful earthquakes result, which cause tremendous amounts of damage
creep regions of transform boundaries
slow constant motion of the plates past each other
The amount of mass per unit volume
Dense plates subduct below less dense plates
mountains that build themselves out of their own expelled debris.Volcanoes are frequently found near plate boundaries and less frequently at hotspots within plates.Most volcanoes above the Earth are found at subduction zones of converging boundaries as found in Chile, South America or the Mariana Islands in the Pacific. Many volcanoes exist beneath the ocean at diverging oceanic
boundaries like at the Mid -Atlantic ridge.
- revise volcanoes form act book
As plates move past each other, they
often displace huge volumes of ocean water
and this can result in a series of monstrous
waves. As tsunamis reach shallow water they slow down and their height or amplitude increases many times
over.The fast moving water can destroy
anything in its path including homes, building and
evidence to support theory of plate tectonics
- shorelines of various continents fit together
-Similar fossils have been found on continents separated by ocean thousands of km apart
-rock formations can be matched up layer by layer suggesting they were formed at the same time in the same area
-Similar glacial movement patterns also match on continents separated by thousands of kilometres
-magnetic striping: after new rock is formed, it has magnetic characteristics
-all rocks have different characteristics
-the worlds not getting bigger therefore the rocks keep going in a cycle, suggesting that the Earth was once formed as Pangea
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