The Changing Earth Flashcards
What are the four layers of the earth, in order?
Crust, mantle, outer core, inner core
Describe the crust
Outer layer, solid, thinnest layer, 10-80km thick, 2 types- oceanic and continental, contains rocks and minerals
Describe the mantle
thickest layer (2900 km), made of very hot solid rock that can flow, gooey (plastic like), drives the movement of Earth’s continents which sit on plates on the mantle.
Describe the outer core
liquid, (2300 km thick), made of metals- iron and nickel, where the magnetic field comes from (detected by compasses)
Describe the inner core
1220 km, 6000 degrees c, made mainly of iron and nickel, pressure (gravity) from the layers above squeezes it into a solid sphere
Identify the location of the asthenosphere
Asthenosphere is the upper mantle, just below the crust
Identify the four spheres of the Earth
Lithosphere, atmosphere, hydrosphere, biosphere
Describe the Lithosphere
(crust), solid outer layer of the earth, divided into tectonic plates; continental and oceanic
Describe the Atmosphere
envelope of gases surrounding the earth
Describe the Hydrosphere
all water on the Earth’s surface such as lakes and seas but sometimes including water above the surface like clouds.
Describe the Biosphere
Regions of the surface and atmosphere of the earth occupied by living organisms
Outline the theory of Continental Drift by Alfred Wegener
Proposed in 1915, the theory that the continents were once joined as a SUPERCONTINENT called Pangea but had moved apart. This split into two smaller continents called Gondwana and Laurasia
Identify the supercontinents
Pangea, Gondwana and Laurasia
Outline the theory of plate tectonics
The theory that Earth’s land masses are in constant motion. It states that Earth’s outer layer (lithosphere) is divided into more than 15 massive pieces called Tectonic plates. These plates move around the asthenosphere (upper mantle) interacting at boundaries, shifting the continents which sit on the plates and producing new landforms.
Identify that the earth consists of huge cracked tectonic plates that are larger than the continents.
yes
Outline the evidence for the theory of Plate Tectonics
Continental drift is a large piece of evidence because without the plates, the continents wouldn’t be able to move. Earthquakes along plate boundaries called fault lines, similar fossils and rocks on seperate continents, and matching shapes of continents that look to fit together as a jigsaw puzzle and once a large continent.
Explain how the Earth’s plates move as a result of convection currents in the mantle and as a result of gravitational forces
heat from the core makes magma in the mantle rise toward the crust. As the hot current nears the crust, it begins to cool and sink back towards the core. As the magma sinks, it drags the plates across the surface of the Earth.
Identify the three major types of plate boundaries
Divergent (spreading away from each other), Convergent (collision into or towards each other), Transform (sliding past each other)
Describe the process of a Converging plate boundary
2 types- (1) if oceanic meets continental or (2) if continental meets continental
(1) Oceanic crust is denser than continental and therefore goes beneath continental when they meet (process known as subduction). This causes friction which produces heat and melts some of the rock making the continental crust. Volcanoes can form as a result of this. (2) when continents meet head on, the crust tend to buckle and pushed upwards or sideways. This forms mountains and sometimes earthquakes.
Describe the process of Diverging plate boundary
spreading zones occur in oceanic crust where two plates are moving away from each other. Magma wells up in the mid-ocean ridge and forms new crust. Plates apart and new crust is created by magma pushing up from the mantle and solidifying.
Describe the process of Transforming plate boundary
Crust is neither produced nor destroyed as the plates slide past each other. They get caught and when they suddenly break apart energy is released, Earthquakes result from this movement.
What is an earthquake?
Vibration of the earth produced by the rapid release of energy.
Identify the 3 main types of waves during an earthquake
P waves (primary), S waves (secondary) and L waves (Love)
