EOY TECTONICS Paper 1 Flashcards
WHAT FORMS EARTHS SURFACE
CRUST
what is crust
a rock layer forming the upper part of the lithosphere
what is lithosphere and describe its texture and what it includes
the upper layer of earth. It is cool and brittle. Includes the very top of the mantle and the crust
What is the lithosphere split into
into tectonic plates
the tectonic plates that the lithosphere is split into move at what rate and on what layer
move very slowly, 2-5cm per year, on a layer called the asthenosphere
what is the asthenosphere
part of earth’s mantle, is hot and semi-molten and lies beneath the tectonic plates
two types of core
outer core, inner core
two types of mantle
asthenosphere, lower mantle
two types of lithosphere
continental crust, oceanic crust
briefly describe and name the two types of crust
continental curst; forms on land , mostly made of granite which is a low density igneous rock. thicker and less dense
oceanic crust; under the oceans and is much thinner, denser and made of igneous rock called basalt. thinner and more dense
what are plate boundaries
where plates meet
direction that plates move in is determined by what
the type of boundary
the movement of plate creates three types of boundary; name them
DIVERGENT, CONVERGENT AND CONSERVATIVE
most earthquakes and volcanoes are found on what
plate boundaries
why do tectonic plates move
due to convection currents in the mantle
how do we know that inside the earth is hot
because of
molten lava spewing from active volcanoes
hot springs and geysers
what is heat from inside the earth called
geothermal
what is geothermal
‘earth heat’/ heat inside the earth
what is geothermal heat caused by
by the radioactive decay of elements like uranium and thorium in the core and mantle. This raises the core’s temperature to over 5000 degrees C.
what is radioactive decay
atoms of unstable elements that release particles from their nuclei and give off heat
why inner core stays solid
because its under huge pressure and is so deep
why is outer core liquid
because it is under lower pressure
as heat rises from the outer core, it creates 1) __________ _______ in the liquid outer core and mantle. These vast mantle 2) ______ ______ are strong enough to move the 3)______ ______ on the Earth’s surface.
1) convection currents
2) convection currents
3) tectonic plates
The crust is divided into _____ called ______
1) slabs 2) tectonic plates
the parts of convection cells where heat moves towards the surface are called what
plumes
what are plumes
the parts of convection cells where heat moves towards the surface. The mantle in a plume is less dense. Plumes bring magma to the surface. If magma breaks through crust, it erupts as lava in a volcano.
what is magma
molten rock
some plumes rise like long sheets of heat. What do these form
divergent plate boundaries at the surface
other plumes are like columns of heat. what do these form
hot spots
where do convection currents only occur within
the upper mantle (asthenosphere) where it is semi-molten
how convection currents work step by step
1) energy from radioactive decay in the core heats up the fluid asthenosphere
2) the hot liquid is less dense than its surroundings, so it rises upwards
3) when it reaches the top, it cools
4) it becomes more dense, and therefore sinks back down to the bottom
5) It is heated up again, and the cycle continues
6) The plates, which lie on top, are pushed and pulled by the convection currents in the asthenosphere
what is a convection current
the movement of a fluid by a difference in temperature or density
