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Rocks
chemistry
3 types of rock | igneous, metamorphic, sedimentary |
sedimentary rock formation? | deposited sediments layer and the pressure makes sedimentary rocks |
metamorphic rock formation? | under high pressure and temperature (changes form). higher pressure = larger grains |
igneous rock formation? | rocks melt, cool and recrystrallize |
intrusive igneous? | cools as it travels, hardens below ground. cools slowly. large crystals |
extrusive igneous? | solidifies around the volcano, cools on the surface. cools fast. small crystals |
rock cycle starting from weathering | weathering of rocks on surface, erosion and transport, deposition of sediment, burial and compaction, SEDIMENTARY ROCK, deformation and metamorphism, METAMORPHIC ROCK, melting, crystallisation of magma, IGNEOUS ROCK |
3 types of weathering | physical, chemical, biological |
physical weathering | water seeps into cracks, freezes and expands, breaking the rock apart over a long time. FREEZE THAW |
chemical weathering | slightly acidic rainwater reacts with rocks to form new minerals. ACID EROSION |
biological weathering | plants' roots are put down cracks in the rock to find moisture. as the plant grows, the roots gradually prize the rock apart. |
erosion | the removal of the products of weathering from where they were formed |
how are bits of rocks transported? | wind, water, glacier |
3 main layers of Earth from centre | core, mantle, crust |
inner core is in what state of matter? | solid |
outer core is in what state of matter? | liquid |
crust is made up of? | continental crust and oceanic crust |
3 properties of continental crust | thick (10-70km), buoyant (less dense than oceanic crust), mostly old |
3 properties of oceanic crust | thin (7km), dense (sinks under cont crust), young |
how many major plates are there | 12 |
3 types of plate boundaries | divergent, convergent, transform |
divergent | plates move apart, new material is erupted to fill in the gap, ridges will spread. |
convergent | C-C forms mountains, O-C is called subduction. oceanic lithosphere subducts under continental lithosphere. O-O forms a subduction zone |
transform | plates slide past each other, form fault lines |
define lithosphere | crust + upper mantle. it is rigid |
how are plates moved around | mantle hot convection cells |
particle size clues | if particles are close in size, well sorted (wind, water slowing down steadily). if particles are different sizes, poorly sorted (abrupt slowing down of river) |
particle shape clues | a glacier cushions the rock so less collisions (more jagged rock).a fast-flowing river flings rocks and stones against each other (more smooth and rounded). |
graded bedding clues | river sediment builds up on the continental shelf. if it gets dislodged it tumbles forward into deep ocean water and settles on the ocean floor. |
cross bedding clues | layers of sediment beds lie at different angles, reflecting the direction of flow of the wind or water that deposited them. wind deposited sand dunes are often like this. |
ripple marks clues | suggests sediment was shaped by a current of wind or water after it has been deposited |
mud cracks clues | suggests that the watery environment in which this sediment was deposited dried up at some point. |
aureole definition | the metamorphosed zone around the intrusion |
contact metamorphism | rocks in contact with molten magma can undergo contact metamorphism. the change can extend from a few cm to a few km into the rock, depending on how big and hot the body of magma is. |
regional metamorphism | rocks get buried under sediment, or trapped by large movements in earth's crust (as in mountain building). extends over 1000s of sq km. |
dike | intrudes across rock layers |
laccolith | mushroom-shaped |
batholith | irregular and over 100 sq km of its surface is exposed. |
sill | intrudes between rock layers |
what makes magma viscous? | minerals like silica. |
12 main plates | pacific, fiji, scotia, nazca, eurasia, north american, south american, caribbean, antarctic, arabian, indian, australian |
hi | hi |