Flashcards
Year 9 Earth and Space Sciences Revision
Cards in this deck (50)
- 1What is continental drift?Continental Drift is the theory that all continents were once connected to each other and had drifted apart made by Alfred Wegener.
- 2What evidence was there for continental drift?-The coastlines of continents seemed to fit together
-Fossils of the same species were distributed over continents that were far apart
-Evidence of drastically changed climates
-Identical rock formations and features were found on different continents - 3What is Pangaea?What Alfred Wegener called the giant landmass of all the continents joined together.
- 4What is Gondwana and Laurasia?The pieces that Pangaea broke up into. Gondwana contained the southern continents and Laurasia contained the northern continents.
- 5What are tectonic plates?A large layer of solid rock that covers part of the surface of Earth. Part of the Earth’s lithosphere that is broken into pieces.
- 6What are the forces that cause plate movement?The main forces behind plate movement are:
Slab-pull
Ridge-push
And Convection Currents - 7What are convection currents?The current or flow of air or liquid that results from the transfer of thermal energy through convection. Hotter, less dense materials rise, and colder, denser material sinks. The hot material at the top slowly cools and sinks letting other hot material rise into its place. Occurs in the asthenosphere. The hot magma drags the plates along as it flows sideways.
- 8What is slab-pull?The largest force in plate movement. When two plates come together one is pushed under the other. The subducted plate continues to sink.
- 9What is ridge-push?When two plates move apart, magma from the mantle rises up to fill the gap and forms raised ridge in the ocean floor. As this ridge is hot and heavy, it expands and pushes the rest of the plate away from the ridge; causing it to move.
- 10What are some of the major plates?Pacific Plate, South American Plate, North American Plate, African Plate, Eurasian Plate, Indo-Australian Plate, Antarctic Plate.
- 11What are the 3 types of plate boundaries?Converging, Diverging and Transform.
- 12What are converging boundaries?Occur when two plates are colliding into each other. Known as destructive boundaries – rock is destroyed.
- 13What are the 3 types of converging boundaries?Oceanic-Continental – oceanic plate sinks under the continental. Oceanic plate melts from the hot magma. Continental forms mountains and volcanoes, oceanic forms deep ocean trenches.
Oceanic-Oceanic – older and denser plate subducts. Forms a deep trench and a volcanic island arc.
Continental-Continental – crust crumbles and both are pushed up to form mountains - 14What are diverging boundaries?Occur when two plates are moving apart from each other. Known as constructive boundaries – new crust forms. Form mid-ocean ridges.
- 15What are transform boundaries?Occur when two plates are sliding parallel to each other in opposite directions. Can cause earthquakes when the plates suddenly slip past each other. Usually have fault lines.
- 16What are the 2 different types of crust?Oceanic and Continental Crust.
- 17Oceanic crustThe crust that forms the ocean floor.
- 18Continental crustThe crust that forms the continents.
- 19What is a subduction zone?When oceanic crust collides with continental crust and the oceanic plate sinks below the continental plate.
- 20What is seafloor spreading?A theory that the middle of the ocean is spreading apart, forming new oceanic crust.
- 21What is the asthenosphere?Upper layer of the Earth’s mantle, where convection currents occur. Made up of rocks that have become soft enough to move from the high temperature.
- 22What is the lithosphere?Solid, outer part of the Earth, the crust and top of the mantle. Made up of rocks. The part we live on.
- 23What are the layers of the Earth?Crust – outer layer of the Earth
Mantle – located beneath the crust. Layer of molten rock.
Core – Centre of the Earth. Made up of heavy metals. Divided into outer and inner core. Outer core is liquid and inner core is a solid sphere. - 24What is magnetic striping?Stripes of magnetic minerals that parallel the mid-ocean ridges.
- 25What is a rift valley?A deep valley that forms as a result of tectonic plates moving apart on land.
- 26What is a mid-ocean ridge?A series of underwater mountains that form as a result of tectonic plates moving apart and allowing magma to rise to the surface.
- 27How is the ocean floor mapped?Using SONAR.
- 28What is a fault line?A fracture in rock where the tectonic plates have moved.
- 29What is the theory plate tectonics?The theory that the Earth is divided into a series of plates that are continually moving.
- 30What is an ocean trench?A deep trench in the ocean floor that is much deeper than the rest of the ocean floor.
- 31Calculating Depth using SonarDistance (m) = Speed (m/s) x Time (s)
Speed = 1482 m/s
Time = sonar ÷ 2 - 32What are volcanoes?Volcanoes are places where extremely hot material from below the Earth's surface erupts at the surface
- 33What is density?How closely packed the particles are in a substance. Oceanic crust is denser than continental crust.
- 34What do volcanoes erupt?Gases (steam and hydrogen sulfide), ash, lava, lumps of volcanic rock (scoria)
- 35Where do volcanoes form?At weak spots in the Earth's crust - the edge of tectonic plates and where magma has accumulated below the hot spots.
- 36What are the types of eruptions?Effusive, explosive, pyroclastic flow.
- 37EffusiveOccur when hot and runny basalt magmas reach the surface. Dissolved gases escape easily as the magma erupts, forming lava that flows downhill quite easily.
- 38ExplosiveOccur when cooler, more viscous magma reaches the surface.
- 39—
- 40What is pyroclastic flow?When a cloud of ash, rock and gas at about 500C rushes down the volcano like an avalanche at over 100km/h
- 41Volcanoes formed at diverging platesThe separating plates thin the crust, as new magma flows to the surface and solidifies. This lowers the pressure on the underlying rocks of the asthenosphere as they melt. The magma created from this then finds its way up through the weakness.
Can form new seafloor or volcanic islands. - 42Volcanoes formed at converging platesWeakness in the crust is caused when subduction occurs. This forms a deep ocean trench just offshore. This generates a lot of heat, causing the sinking rock underneath to melt. When the magma formed by the melting rock aches the surface, a volcano is formed. Volcanoes in the ring of fire are caused by converging crust.
- 43What are hotspotsIsolated places where a lot of magma is being created. Can occur under oceanic or continental crust. Tectonic plates move across them.
- 44Volcanoes formed at hotspotsIn oceanic crust forms a chain of islands. Eg. Hawaiian islands. Each island forms at it sits over a hot spot. As the plates move, he island goes with it and so it no longer sits over the hotspot. A new part of the plate is over the hotspot, forming a new volcano.
- 45What are the classification of volcanoes- Active - has had at least one eruption during the last 10,000 years (can be erupting or dormant)
- Erupting - an active volcano that is having an eruption
- Dormant - an active volcano that is not erupting, but supposed to again
- Extinct - has not had an eruption for at least 10,000 years and is not expected to. - 46What are the types of volcanoes- Shield
- Cone
- Fissure Vents
- Caldera - 47Shield VolcanoesAre wide and flat volcanoes, with gently sloping sides. Caused by the very runny lava that flows gently and continuously. Builds up slowly from the thousands of lave flows. Formed at hotspots or diverging plates. Eg. Hawaiian islands - Mauna Loa
- 48Cone VolcanoesBuilt by fragments being ejected from a vent, piling up around the vent, in the shape of a cone with a central crater. Formed at subduction zones. Eg. Pu'u 'Ō'ō
- 49Fissure VentsHave no central crater, instead they have giant open cracks in the ground. The expel large quantities of lava that can spread very far. When the lava cools and solidifies, the surface remains flat. The cracks are usually buried, so they do not look like a volcano. Usually found at diverging plates. Eg. Radial fissure vents of the Hawaiian islands.
- 50CalderaThe largest and most explosive volcanoes, which can eject hundreds of kilometres of magma onto Earth's surface. Usually formed from the collapse of land following a large volcanic eruption. This forms a large depression called a Caldera. Eg. The Yellowstone Caldera in Yellowstone National Park, USA.
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- Flashcards on Year 9 Earth and Space Sciences Revision, created by Caoimhe Pettit on 30/05/2020.
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