Unit 1 - AOS2 - Lithosphere Flashcards
Earths Crust
- Made from slabs of igneous rocks and soil
- 40km under continents and 10km under oceans
Order of the earths layers
- Lithosphere (crust + upper mantle)
- Mantle (the rest of it)
- Core
- Outer core: molten and composed mainly of nickel and iron
- Inner core: composes mainly of iron and is solid due to pressure/weight.
Continental drift
The movement of the plate tectonics on earth, at different rates and directions.
- Move slowly (1-12cm per year)
Convection currents
Is when molten material in the mantle moves, nudging the plate tectonics and causing them to move.
Transform-fault boundaries
- Slide horizontally past each other
- Cause earthquakes
Divergent Boundaries
- Plates move apart creating new lithosphere
- Forms mid ocean ridges and rift valleys
- Characterized by volcanic activity and earthquakes
Convergent boundaries
When plates collide (one is pulled into the mantle and recycle)
Igneous rocks
Form from the cooling of magma –> that did not reach the surface.
e.g: basalt, obsidian
Sedimentary Rocks
Form from deposits or eroded particles of rock, soil and remains of dead organisms
- Overtime increased pressure on the layers compresses them into rocks
e.g. limestone, conglomerate
Metamorphic Rocks
Are igneous or sedimentary rocks that have been altered by heat, pressure and change within earth’s crust.
e.g. marble, gneiss
Weathering (rocks)
- Breaks down and sculpts the rocks
Erosion
Erosion transports fragments of rocks
Deposition
Rocks and minerals that were weathered and eroded, are deposited into another place.
Define soil
Mixture of particles that have been formed over long periods of time by the weathering rocks and remains of eaf organisms.
Define Humus
Decomposing organic material
- highly fertile
How do worms help with soil ?
- help turn the soil bringing humus from top soil and mix with the other layers of soil
What does the proportion of particles determine ?
It determines the texture of the soil
And therefore the properties :
- aeration
- density
- drainage
- capacity to hold water and nutrients
Define Loam
It is the best soil for growing crops in due to it having equal ratios of sand, silt and clay
Porosity
Is the size of the space between each particle
- allowing water and air to penetrate through the soil
Sandy soil characteristics and porosity
- allows water to pass through quickly
- high porosity
Clay soil characteristics and porosity
- retains water for long periods making it water logged
Layers of soil
- 0 organic matter = humus
- A horizon = topsoil
- B horizon = subsoil
- C horizon = substratum
Marble
- metamorphic
- included crystals and is when limestone is compressed into the earth and subjected to heat and pressure
Conglomerate
- sedimentary
- includes pebbles, stones and smaller particles and is compressed together from waves or water
Obsidian
- igneous
- smooth glassy surface
- created from lava or magma that cools so quickly no crystals can be formed
Basalt
- igneous
- is cooled lava that contains gases from volcano
- creates gas bubbles
Limestone
- sedimentary
- fossils are visible in the rock
- fossils formed from seashells and skeletons from dead marine animals are compressed into the sea floor.
With other sediments
Gneiss
- metamorphic
- Ribbon like layers
- forms from other rocks being pressurised with heat deep within the earths crust
