Science: Key Concepts
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- What happens at deep-ocean trenches?
- In a process taking 10s of millions of years, part of the ocean floor sinks back into the deep-ocean trenches
- What causes convection currents?
- Heating and cooling of the fluid, changes in the fluid's density, and the force of gravity combine to set convection currents in motion
- What was Alfred Wegener's hypothesis about continents?
- Wegener's hypothesis was that all the continents had once been joined together in a single landmass and have since drifted apart
- What are the 3 types of plate boundaries?
- There afe 3 kinds of plate boundaries: divergent boundaries, convergent boundaries, and transform boundaris. A different type of plate movement occurs along each.
- What is the process of sea-floor spreading?
- In sea-floor spreading the sea floor spreads apart along both sides of a mid-ocean ridge as new crust is added. As a result, the ocean floors move like conveyor belts, carring the continents along with them.
- How have geologists learned about Earth's inner structure?
- Geologists have used 2 main types of evidence to learn about Earth's interior: direct evidence from rock samples and indirect evidence from seismic waves
- What is the theory of plate tectonics?
- The theory of plate tectonics explains the formation, movement, and subduction of Earth's plates
- What evidence supported Wegener's hypothesis?
- Wegener gathered evidence from different scientific fields to support his ideas about continental drift. He studied land features, fossils, and evidence of climate change
- How is heat transferred?
- There are 3 types of heat transfer; radiation, conduction, and convection
- Why was Wegener's hypothesis rejected by most scientists of his day?
- Wegener could not provide a satisfactory explanation for the force that pushes or pulls the continents
- What is the evidence for sea-floor spreading?
- Several types of evidence supported Hess's theory of sea-floor spreading eruptians of molten material, magnetic stripes in the rock of the ocean floor, and the ages of the rocks
- What causes convection currents in Earth's mantle?
- Heat from the core and the mantle itself causes convection currents in the mantle
- What are the characteristics of Earth's crust, mantle, and core?
- The 3 main layers of Earth are the crust, the mantle, and the core. These layers vary greatly in size, composition, temperature, and pressure