Tectonic Plates Objective: To learn how tectonic plates move and what evidence we have for continental drift Starter: Word search – rock cycle review

Tectonic plates The crust is made of about twelve plates. The crust is made of about twelve plates. These are like big rafts floating on the semi- molten mantle. These are like big rafts floating on the semi- molten mantle. Convection currents within the mantle cause the plates to move. Convection currents within the mantle cause the plates to move. Although they only move about 2 cm/year (same speed as fingernail growth) this can have huge effects over long periods of time. Although they only move about 2 cm/year (same speed as fingernail growth) this can have huge effects over long periods of time.

Convection currents

Modeling convection currents Put on goggles Put on goggles Fill the beaker about ¾ full with water Fill the beaker about ¾ full with water Gently warm the beaker on one side with the candle Gently warm the beaker on one side with the candle Using tweezers, place a crystal on the heated side of the beaker Using tweezers, place a crystal on the heated side of the beaker NB: The crystals will stain yourclothes and fingers NB: The crystals will stain your clothes and fingers

Convection current demonstration Observe how the purple trails move around in a loop Observe how the purple trails move around in a loop

Convection current demonstration Observe how the purple trails move around the convection loop Observe how the purple trails move around the convection loop

Pangaea Continental Drift On average, the plates only drift about 2cm/year. However 2cm multiplied by a million years is a long way! On average, the plates only drift about 2cm/year. However 2cm multiplied by a million years is a long way! Scientists think the continents were originally all together in a super-continent called Pangaea. Scientists think the continents were originally all together in a super-continent called Pangaea. Over millions of years they have drifted to their present positions on the floating tectonic plates. Over millions of years they have drifted to their present positions on the floating tectonic plates. Millions of years

Continental Drift People once thought that the oceans and the continents were formed by shrinkage from when the Earth cooled down after being formed. Alfred Wegener proposed something different: These continents look like they “fit” together. They also have similar rock patterns and fossil records. These two pieces of evidence led me to believe that there was once a single land mass.

Evidence for Continental Drift The theory is supported by several pieces of evidence. For example, if we consider Africa and South America there is: The “jigsaw fit” The “jigsaw fit” The similarities in the rock layers from Africa and South America. The similarities in the rock layers from Africa and South America. Similarities in the type and age of fossils. Similarities in the type and age of fossils. Evidence of related species that definitely did not swim the Atlantic Ocean! Evidence of related species that definitely did not swim the Atlantic Ocean! Jigsaw fit Similar rocks and fossils

Main Task Write a memo from Alfred Wegener to a fellow geologist (scientist who studies rocks) Write a memo from Alfred Wegener to a fellow geologist (scientist who studies rocks) The memo should explain: The memo should explain: a) What is meant by continental drift b) Evidence that proves the continental drift theory

Wrap up 3 exam questions – class activity 3 exam questions – class activity In pairs, write 3 questions of your own that can be used as a quiz at the start of the next lesson In pairs, write 3 questions of your own that can be used as a quiz at the start of the next lesson

Q1 - The diagram shows the three main layers of the Earth. The middle layer is called the..... crust. lithosphere. magma. mantle.

Q2 - The diagram shows the three main layers of the Earth. The middle layer..... has convection currents which move very slowly. is made of solid rock which cannot flow. is made up of metamorphic rocks. is made up of sedimentary rocks.

Q3 - The diagram shows the three main layers of the Earth. The inner part of the inner layer (core) is..... liquid and made from aluminum and silicon. liquid and made from iron and nickel. solid and made from aluminum and silicon. solid and made from iron and nickel.

Home work How are natural disasters such as earthquakes/tsunamis linked to the movement of tectonic plates? How are natural disasters such as earthquakes/tsunamis linked to the movement of tectonic plates? You should use the library/internet to research this HW You should use the library/internet to research this HW Aim to jot down at least 5 facts Aim to jot down at least 5 facts