earth science Flashcards
What is a rock?
A natural substance made when geological processes occur. It is composed of solid crystals or different minerals.
cementation, what is it and what does it do?
The gluing together
of sediment by new
mineral crystals —
Cementation can cause sediment
grains to stick together, forming
sedimentary rock.
compaction - what is it and what does it do?
The squeezing of sediment by
the weight of overlying layers —
Compaction can cause sediment
grains to stick together, forming
sedimentary rock.
continental crust
Crust that lies beneath a
continent —
Continental crust is about
25–70 km thick and is less dense
than oceanic crust.
continental drift
The movement of continents
around the surface of Earth —
Continental drift theory was
proposed by Alfred Wegener in
1912 but was widely accepted
only in the 1960s.
what causes continental drift?
divergent boundaries
convergent boundary
A place where two tectonic
plates move towards
each other —
At convergent boundaries,
mountain ranges, ocean trenches
and volcanoes can form.
the process of convergent boundaries: oceanic-oceanic
oceanic-oceanic: the plate subducts beneath the other, making a trench, and sinks into the mantle to melt into magma. This magma then rises to the weakened part of the plate to form underwater volcanoes
the process of convergent boundaries: continental - oceanic
convergent - oceanic: the oceanic crust which is denser, subducts beneath the continental crust, creating a trench where the oceanic sinks into the mantle to form magma. This magma also makes volcanoes with eruptions.
What are the properties of rock?
Cleavage, hardness, lustre, streak, colour
What are crystals?
Most crystals are minerals made up of a crystalline structure.
divergent boundary
A place where two tectonic
plates move away from
each other—
At divergent boundaries, rift
valleys and mid-ocean ridges
can form.
the process of divergent boundaries:
oceanic-oceanic
Two oceanic plates separate and make a mid-ocean ridge. The plate is also weakened, allowing magma to seep through
the process of divergent boundaries:
continental- continental
Two plates made up of continental crust split and create a rift-valley. The plates are both weakened allowing magma to rise through and form a volcano.
What happens to a rift-valley overtime?
Rift valleys are formed from divergent boundaries and overtime, water rises through to become a mid-ocean ridge. This turns into a basin and magma rises through to make an underwater volcano. While all of this is taking place, it expands the oceanic crust
What is the relationship of crust and plate tectonics.
The theory of plate tectonics states that Earth’s surface is broken up into rigid slabs of rock. These are called tectonic plates.
The plates are made up of the crust and the solid upper layer of the mantle. Taken together, these are known as the lithosphere.
The lithosphere sits on a layer of the mantle that is partially melted. This semi-liquid layer allows the plates to move horizontally, carrying the continents with them.
crust
The outermost layer of the earth - part of the lithosphere
transform boundaries
A place where two tectonic
plates slide past each other
At transform boundaries,
earthquakes often occur as
pressure along faults is suddenly
released.
earthquake
The sudden shaking of
Earth’s surface —
An earthquake is a natural hazard
that occurs when two slabs
of rock suddenly slip against
each other.
erosion
The wearing away and
removal of rock —
Eroded sediment is transported
by wind, water or ice.
chemical weathering
When rocks are changed in their substances or they are broken down by chemicals
Why do different rocks weather at different rates?
their hardness
Physical weathering
weathering that occurs physically and breaks down rocks into small fragments
name some examples of :
chemical weathering
CO2 + Water = carbonic acid
Iron + Oxygen = iron oxide (rust)
acid rain
name some examples of: physical weathering
raining then freezing into cracks (frost/ice wedging)
tree roots growing
rain
sudden change in temperature
fossil
The remains or traces of an
ancient organism preserved
in rock — Fossils provide information about
how life evolved and how Earth’s surface has changed.
geologist
scientist who studies the Earth
hotspots
An unusually hot part of the
mantle where volcanoes
can form — At hotspots, magma can rise
through the crust to form
volcanoes, even away from
plate boundaries.
igneous rock
Any rock - formed by the cooling of magma and lava and can be porphyritic, aphanitic and have vesicular texture. There are two types: intrusive/extrusive
innercore
the innermost layer of the Earth — the innercore is a solid mixture of iron and nickel at extreme temperatures and pressure
lava
liquid molten rock exposed to the surface of the Earth, outside of the volcano
magma
liquid molten rock beneath the Earth’s surface in a magma chamber
mantle
the thickest layer of Earth, between the core and crust. It is made of solid and is partially melted.
Lithosphere
the crust and upper-part of the mantle
melting
a change of state from solid to liquid
metamorphic rock
any that has been changed by extreme pressure and heat — this heat changes their crystals structure and minerals
mid-ocean ridge
an underwater mountain system where new oceanic crust forms
mineral
a natural substance usually found as crystals within rocks
mitigation
an action that decreases the harmfulness of an event
natural disaster
An event in the natural world that causes death or destruction
natural hazards
An event in the natural world that endangers living things : volcanoes, tsunamis, earthquakes, landslides-
ocean trench
A deep valley in the ocean at a convergent boundary when a plate subducts
oceanic crust
The crust that lies underneath the ocean and is 5 - 10km thick and denser than continental
outercore
the layer of earth that lies between the mantle and innercore - liquid mixture that generates Earth’s magnetic field
parent rock
the original rock before a metamorphic is formed
plate boundary
the border between two tectonic plates
pressure
the amount of force applied to a certain area of the Earth
relative dating
a method to determine whether a rock is older or younger than another — lower = older
rift valley
a long depression formed when divergent boundaries occur
rock cycle
the set of changes that turn one rock into another
seafloor spreading
the formation of new oceanic crust at a mid-ocean ridge.
sediment
small rock fragments such as mud, sand or gravel.
sedimentary rock
any rock that is formed when weathering, erosion, deposition, compaction and cementation occur — can also be made from fossil remains
solidification
the change of state from liquid to solid
subduction
the sinking of one tectonic plate beneath the other
supercontinent
a single landmass made up of smaller continents joined together - PANGAEA
tectonic plate
a section of the crust and upper mantle - the lithosphere which is broken up into pieces and move differently because of the mantle
transform boundary
where two plate slide past each other along faults and pressure is built up because they are rigid. They trigger earthquakes
tsunami
A large ocean wave caused by an earthquake or coastal landslide
volcanic eruption
The release of magma from the magma chamber, erupting through a volcano
weathering
the breakdown of rocks into small grains, sediment and soil
How can earthquake geologists use sedimentary rocks to date back when earthquakes occur?
Earthquake geologists can look at the sedimentary layers of the rock and the layers that got affected by the earthquake are older and the earthquake is younger than them
Using the Mohs hardness scale which is a scale from 1-10, Granite is 6.5 on the scale. Quartz is able to scratch Granite and leave a mark, what does this suggest?
Quartz is harder than Granite and is harder than 6.5 as well
what are the natural hazards caused by volcanoes
lahar, lava, volcanic ash, volcanic gas, pyroclastic flows
what is the K-T boundary?
The K-T boundary is a layer of sedimentary rock which has shocked quartz and a high level of iridium.
