Download Exemplar: Describe the theory of Plate Tectonics Claim: The theory

Exemplar: Describe the theory of Plate Tectonics
Claim:
The theory of plate tectonics states that outer layer (Lithosphere) of the Earth is composed of tectonic
plates that move a few centimeters every year.
Evidence:
Alfred Wegener noticed that the continents looked like puzzle pieces meant to fit together when looking
at some maps. As he continued to investigate, he found similar fossils and rocks on continents separated
by oceans. He proposed that the continents were drifting. Later Harry Hess discovered the mechanism
that caused the movement.
Reasoning:
Henry Hess discovered mid-ocean ridges, where divergent boundaries occur and spread the sea floor.
Then scientist realized that heat was rising up from the core of the Earth causing convection currents to
occur in the asthenosphere (mantle). This current moved the different tectonic plates. At plate
boundaries different geologic events occur. Convergent boundaries, where plates come together,
mountains and volcanoes form. Transform boundaries, where plates slide past each other, earthquakes
are most likely. Divergent boundaries, where plates move apart, mid-ocean ridges and valleys can form.