Plate Tectonic Theory

Plate Tectonic Theory

What are the mechanical layers of the earth?

Learning Objective

• describe the historical development of evidence that supports plate tectonic theory

Why Do We Have Volcanoes, Earthquakes, Mountains and Valleys?

Ever wondered where these formations on earth come from? Many of these actually come from under the earth. But how do we know since we can't actually see deep into the earth?

What is Inside of Earth?

• The Lithosphere is made of the upper mantle and crust

• The mantle is made of three different areas. It's the top one, Asthenosphere that the crust moves on top of.

What Causes the Plates to Move on the Asthenosphere?

• Heat from within the mantle rises, cools as it reaches the top, and falls back down.

• This concept, Convection, slowly moves the plates on top to move.

Multiple Choice

Which mechanical layer does convection occur in that pulls the tectonic plates?

• Crust

• Core

• Asthenosphere

• Mesophere

Alfred Wegner

Developed from the 1950s to the 1970s, the theory of plate tectonics is the modern update to continental drift, an idea first proposed by scientist Alfred Wegener in 1912 which stated that Earth’s continents had “drifted” across the planet over time.

Multiple Choice

Who proposed the theory of plate tectonics?

• Albert Einstein

• Alfred Wegener

• Isaac Newton

• The Mandalorian

Fill in the Blank

This states that _____________ _______ Earth’s continents had “drifted” across the planet over time.

Pangaea

Pangaea is what Alfred Wegener termed the name of all the continents together at the beginning of time. Pangaea means "all the earth" in greek.

If we cannot see Plate Tectonics happening, how do we know it's real?

There are a few evidence, or proofs that support Plate Tectonic Theory.

1. The continents fit together almost like puzzle pieces forming Pangaea (one super-continent)

Evidences for Plate Tectonics

• Fossils on different continents are similar to fossils on continents that were once connected. 

• Most continental and oceanic floor features are the result of geological activity and earthquakes along plate boundaries. 

Evidences cont.

• Most distributions of rocks within Earth's crust, including minerals, fossil fuels, and energy resources, are a direct result of the history of plate motions and collisions and the corresponding changes in the configurations of the continents and ocean basins.

Multiple Select

Which of the following are evidences for Continental Drift?

• The continents fit together almost like puzzle pieces forming Pangaea (one super-continent).

• Fossils on different continents are similar to fossils on continents that were once connected

• Astronomers have broken down this cycle into four primary Moon phases: New Moon, First Quarter, Full Moon, and Last Quarter. Gibbous, Waning Gibbous, and Waning Crescent.

• Most continental and oceanic floor features are the result of geological activity and earthquakes along plate boundaries.