Plate-tectonic theory Flashcards
What is the core?
It is earth’s large centre, it is hot due to radioactive decay
What is the mantle?
A thick layer surrounding the core, it is mainly semi-molten and plastic
What is the crust?
A part of earth’s thin outer shell, it is cool, rigid and brittle
What is continental crust?
A solid rock making up landmasses, it has a relatively low density because it is composed of granite
What is oceanic crust?
A solid rock lining the ocean floor, it has a relatively high density because it is composed of basalt
What is the lithosphere?
It includes the crust and solid uppermost mantle, it is cool, rigid and brittle like the crust
What is the asthenosphere?
It is below the lithosphere, it is a semi-molten mantle and plastic
What are tectonic plates?
The lithosphere is broken into 7 major slabs and several minor ones, plates can be continental / oceanic or both depending on their crust
What do tectonic plates float on?
Tectonic plates float on the asthenosphere and slowly move 1-15 cm/y
What may power plate movement?
Plate movement may be powered by slow convection currents in the mantle driven by heat from the core
What is basal drag
mantle convection may cause basal drag which is friction on the bottom of plates moving plates apart / together / past each other
