Plate Technotes Flashcards
what are the four layers on earth?
crust, mantle, outer core and inner core.
what are two types of crust?
oceanic and continental crust
what is the other name for the crust?
lithosphere
what are the two minerals that are present in the crust?
silica and aluminum
what is the type of rock that is found in the oceanic
crust?
basalt
is the oceanic or continental crust thicker?
continental crust will be thicker than the oceanic crust
how does the thickness of the crust vary?
due to the oceanic and continental area of earth
what is another name for the upper part of the mantle?
astrosphere
what is the uppermost part of the mantle and crust called?
lithosphere
what is the mantle a chief source to?
magma that finds its way up to the earths surface during volcanic eruptions
what are the two types of minerals found in the mantle?
silicon and magnesium
what is the center of the earth?
the core
what are the two types of core?
the outer core and inner core
what state is the inner core in?
solid
what state is the outer core in?
liquid
what is the heavy material that the core is made up by?
nickel and ironw
what is another name for the core?
nife layer
what did people believe about 250 years ago?
that the earth was only a few thousands of years old
who was the first person to realise that this was not true?
James Hutton
what was James Hutton’s assumption about earth?
he believed that earth was much older than 6,000 year old
what was some of the things that James Hutton has noticed?
fossils of marine animals appeared sometimes a long way from the sea or in mountains.
rocks being eroded but there were still many rocks.
rocks were made from eroded sediments.
What are some things that other scientists used to calcutue the age of earth?
rate of cooling
calculation of time take for the tidal friction to slow down earth to reach the 24 hour day
calculation of time take for the sun to condense to its current size and brightness
calculation of time take for oceans to reach its current salt levels based on the rate of erosion .
what did William Thompson (Lord Klevin) believe in?
Earth was cooled from a red hot globe and also that earth is about 20- 40 million old and not 20 - 400 million years old which he said in his previously theory
what did Kelvin based his estimate on?
the temperature of the surface rock
why was Lord Kelvin’s estimate not accurate?
- the liquids mantle underneath the earths crust had convention currents which was supplying additional heat that escaped the interior which warmed the surface.
- radioactive decay also supplied heat.
what did evidence from rocks used to be called?
qualitive
How could people tell the relative age of rocks?
where they were in relations with other (deeper rocks would be more older) and the fossils found in the rock.
what is radioactive dating?
a technology developed by scientists to quantify the age of most rocks
how can scientists measure the age of rocks?
since most rocks contain radioactive elements and these elements decay at a fixed rate they can measure how much the rock has left to figure out the age.w
what did scientists notice about the shape of large land masses?
that africa and south america fit together.
what was scientists best guess on why large land masses fit together?
ocean floor were slowly rising and falling that made land bridges between continents
what did Roberto Mantovani suggest?
volcanic activity and thermal expansion led to the continents drifting apart with the oceans filling in the gaps which he called the Expanding Earth Theory
what was the theory that Alfred Wegner had propsed?
Continental Drift
What was Pangea?
evidence of matching rocks, plant and animal fossils on different continents were once joined in one big continent
what are the two continents that Pangea broke up into
Laurasia (north) and Gondwanaland (south)
what did Wegner suggested on why continents moved?
centrifugal force of the earth’s rotation
what was paleomagnetism?
producing data showing that India has previously been in the southern hemisphere
what was discorved in 1960?
seaflorr spreading
What the realization made in 1960?
that earth crust is made up of large plates floating on top viscous molten rock
what was Alfred Wegners theory changed to?
Plate Tectonis Theory
what was the Plate Tectonis Theory?
it indicated that contients are not drifting aimlessly but are driven by convection currents in the mantle.
which crust is beneath land?
continental crust
which crust is beneath oceans?
oceniac crust
what is the crust made up from?
large plate
which crust is more dense and thinner?
oceaniac crust
how to plate move?
the intense heat in the earth’s core causes the molten rocks in the mantle layer to move in convection currents
what do warm materials do?
rises and then sinks down again and then it is warmed and the process repeates itself
what do convenction currents do to the plates?
drag along the plates
what are the three basis types of movement that plate have when the edges meet one another?
divergent, convergent and transform
what is divergent plate boundary?
when plates move apart from each other
what is transform plate boundary?
pates slide past each other
what is convergent plate boundary?
when plates push against each other
what do convergent boundaries form?
mountain ranges and volcanoes
what is being formed in divergent boudaires?
a new crust
what is being formed in transform boundaries?
earthquake acitivies
what is subduction?
the sideways or downwards movement of the edges of the plates in the crust into the mantle beneath another plate
what is the motion of a transform plate boundary?
horizontal
what do transform plate boundaries form?
fracture
what are the three types of faults?
normal, reverse and transcurrent
