Looking for Patterns in Data GROUP A: EARTHQUAKE ACTIVITY GROUP B: VOLCANO ACTIVITY

Earthquakes and Volcanoes What do you notice about the distribution of earthquakes? What do you notice about the distribution of volcanoes? Do you see any correlations or patterns? Can you think of a possible explanation for the patterns you see? Earthquakes Volcano Ring of Fire Pacific Ocean where many earthquakes and volcanic eruptions occur -

Volcanoes reveal locations where Earth's internal heat escapes to the surface of the planet. Volcanic eruptions are all evidence of Earth's internal heat being released. Earthquakes occur where solid rocks move against other solid rocks. Energy released during earthquakes is generated when rocks break. Locations of earthquakes, therefore, provide information on where Earth's crust breaks in response to pressure. When examined together, most of the basic tenets of plate tectonics are laid bare and seem irrefutable. Scientists developing the key ideas of plate tectonics over the past 40 years had only fragments of these data to work with as they tried to describe, classify, and interpret what they saw

Seafloor age Topography As horizontal pressure is applied to rocks on Earth's surface, ridges, folded mountains and valleys form perpendicular to the direction of the pressure. Conclusion?

Plate Tectonics SES4U 5

Learning Goals By the end of this lesson students will be able to: Describe the types of boundaries (convergent, divergent, transform) between lithospheric plates, Explain the types of internal Earth processes occurring at boundaries Identify major areas of tectonic activity in the world by plotting the location of major recorded earthquakes and active volcanoes on a map

Historical Perspective The Earth's Surface remains relatively unchanged within a human lifetime However in the 1500s a dutch cartographer noticed the apparent fit of of continents on either side of the atlantic Ocean

Continental drift Theory that continents and plates move on the surface of the Earth was proposed by Alfred Wegener in 1915. Continental drift- the earth’s continents had once been joined as a single landmass that broke apart and sent the continents adrift. He called the supercontinent Pangea Wegener

Theory of Continental Drift

Maps by Wegener (1915), showing Continental Drift

Evidence for continental drift Matching coastlines

Evidence for continental drift Matching mountain ranges

Evidence for continental drift Matching rock types and ages of rocks

Evidence for continental drift Matching fossils

Evidence for continental drift Matching glacier deposits 300 million years ago

Theory of Plate tectonics The theory of Plate tectonics was proposed in 1960s based on the theory of continental drift. This is the Unifying theory that explains the formation and deformation of the Earth’s surface. According to this theory, continents are carried along on huge slabs (plates) on the Earth’s outermost layer (Lithosphere).

Earth’s magnetic field New oceanic crust forming continuously at the crest of the mid-ocean ridge cools and becomes increasingly older as it moves away from the ridge crest with seafloor spreading Magnetic stripes on the sea-floor- Magma contains materials that are magnetically effects Minerals act like compass needles and point towards magnetic north. The oher group, however, has reversed polarity lining up like magnets

Tectonic Plates To find distances between the americas, europe and Africa, at the time of pangea you only need to match the magnetic bands within the oceanic crust This helps prove the theory of continental drift and plate tectonics Earth’s outermost layer is divided into 12 major Tectonic Plates (~80 km deep). These plates move relative to each other a few centimeters per year. -earth magnetic field is always changing direction/ reversing iron in the crust reflects this change, shows north and south billions of years ago

Tectonic plates of Earth Glide over the mantel Add this to your Map!

Types of plate boundaries Divergent plate boundaries: where plates move apart Convergent Plate boundaries: where plates come together Transform plate boundaries: where plates slide past each other

Types of Plate Boundaries Normal faults: Plates move away from each other (tension) New lithosphere is formed Causes volcanism not very explosive

Types of Plate Boundaries Reverse/ Thrust Fault: Plates move toward each other (compression) Lighter layer is subducted Lithosphere is consumed Mountain building, earthquakes and explosive volcanism

Transform Boundaries Strike Slip Faults: two plates slide past each other Lithosphere is neither consumed nor destroyed. Responsible for most of the earthquakes, no volcanoes

Types of Faults

What drives plate movement? Ultimately: heat transported from core & mantle to surface Heat transported by convection: Core is ~5,000°C and surface is ~0°C Where mantle rises: rifting Where mantle dives: subduction zones -Convection currents in the magma drive plate tectonics. Heat generated from theradioactive decay of elements deep in the interior of the Earth creates magma (molten rock) in the aesthenosphere. -Mantle convection is the slow creeping motion of Earth's solid silicate mantle caused by convection currents carrying heat from the interior of the Earth to the surface.[3][4] The Earth's surface lithosphere, which rides atop the asthenosphere (the two components of the upper mantle), is divided into a number of plates that are continuously being created and consumed at their opposite plate boundaries.

Homework Reading on Plate Tectonics Answer questions 1-4 on your graphing worksheet