Structure Of The Earth And Currents/earthquakes Flashcards
What is the order of the structure of the Earth?
Crust
Mantle
Outer core
Inner core
Crust
Deepest in mountainous areas
Less than one percent of the Earths volume
Mantle
Mostly solid bulk of Earths interior
Mostly iron
84 percent of Earths volume
Outer core
Fluid layer
2400 KM thick
Inner core
Solid ball
Radius of 1220km
Evidence for the continents being joined together
Jigsaw fit Convection currents Study of fossils Geological patterns Palaeomagnetism
Jigsaw fit
Continents fit together to make huge piece of land called Pangea. Alfred Wegener, a german geologist put this theory forward. Continental drift is the idea the continents are slowly shifting position.
Convection currents
In the mantle, convection currents were found to be slow yet extremely powerful movements of volcanic rock in the mantle. The magma is heated to 5500 degrees Celsius and rises to the crust where they cool and descend only to be heated. This was powerful enough to move the Earths plates.
Convection currents
Process:
1) At the core the temperature is 5500 degrees celsius.
2) Rock nearest the core is heated in the mantle and becomes less dense.
3) Molten rock rises upwards.
4) Temperatures in the upper mantle are cooler and molten rock cools.
5) As it cools, it becomes more dense and sinks downwards.
6) This process happens again and has the power to move continents.
Study of fossils
None of these fossils could have been an animal that could go across huge masses of water and land. Must have lived in Pangea.
Geological Patterns
Similar pattern of rock layers on different continents. Coal has been found in Antartica-requires warm climates to form.
Palaeomagnetism
Mid Atlantic Ridge was made by underwater volcanoes and lava cooling. When lava cools the magnetic iron points to the North Pole. When this reversed to the South Pole, the iron particles in the magma aligned with Earths new population.
Plates
North American Pacific Cocos Caribbean Nazaca South American Antartic African Arabian Eurasian Pacific Philipine Indo-Australia
Convection Plate Boundaries
The plates are pulled apart by the convection currents in the soft rock below them. Liquid rock or magma rises between the plates. It hardens to basalt. Which forms new ocean floor.so the ocean floor is getting wider-by about 2cm a year.
Destructive Plate Boundaries
The Nazca plate is heavier (oceanic crust is heavier. So it gets pushed under at an ocean trench. The rock jolts and grinds its way down causing earthquakes, at the same time. It heats up. Some rock melts and forces its way up through the Andes to form a volcano.
