Chapter 5 Plate Tectonics

How do scientists explore the interior of Earth? Big Question

Scientists explore the interior of Earth through… Direct evidence from rock samples Indirect evidence from seismic waves The way seismic waves travel through Earth reveals the structure of the planet.

What is the composition of Earth? Big Question

The composition of Earth consists of… Crust Mantle Lithosphere Asthenosphere Core Outer Inner.

The Crust Definition Size Composition Temperature - surface The layer of solid rock that includes both dry land and the ocean floor. Size 5 – 70 kilometers thick Composition Basalt and Granite Temperature - surface Pressure - surface

The Mantle Definition Size Composition Temperature – 5,400 ºF The layer below the crust, layer of very hot, solid rock. Size 3,000 kilometers thick. Composition Hot, solid rock Temperature – 5,400 ºF

The Mantle – The Lithosphere Definition The uppermost part of the mantle and the crust together form the lithosphere. Size 100 kilometers thick Composition Stone, crust and mantle Temperature – 5,400 ºF

The Mantle – The Asthenosphere Definition Soft layer of the mantle on which the lithosphere floats Size Varies according to the pressure of the layers above Composition Soft, less rigid rock Temperature – 5,400 ºF

The Core Definition Size Composition Temperature The outer core is a layer of molten metal that surrounds the inner core. The inner core is a dense ball of solid metal. Size 3,486 kilometers thick. Composition Nickel and iron Temperature about 13,000°F

How does heat transfer effect plate tectonics? Big Question

Heat transfer effects plate tectonics through… Radiation The transfer of energy through space warms earth. Conduction The transfer of energy between two materials that touch is responsible for some of the heat transfer within Earth. Convection The transfer of heat by the movement of currents within a fluid. Convection currents flow through the mantle because of the great heat and pressure. This is responsible for the movement of Earth’s plates and the magnetic field.

Why do Earth’s plates move? Big Question

Earth’s plates move due to… Continental Drift All the continents were once joined together in a single landmass and have since drifted apart. Pangaea The supercontinent formed when all the continents were connected. Eventually the continents drifted apart.

Evidence Land Features Fossils Climate Mountain ranges on continents lined up. Fossils Like fossils are found on the coasts of countries that were once connected. Climate Fossils indicating a warmer or colder climate are found where they are now unlikely to exist.

How does the ocean floor adapt to the movement of plates? Big Question

The ocean floor changes due to… Sea-floor spreading The sea-floor spreads apart along both sides of a mid-ocean ridge as new crust is added. Sea-floor spreading is supported by: Eruptions of molten material Magnetic stripes in the rock of the ocean floor The ages of rocks

Subduction at Trenches The process by which ocean floor sinks beneath a deep-ocean trench and back into the mantle.

How do plates move? Big Question

Plates move according to… The Theory of Plate Tectonics Explains the formation, movement, and subduction of Earth’s plates.

Plate Boundaries Divergent Boundaries Convergent Boundaries The place where two plates move apart. Convergent Boundaries The place where two plates come together. Transform Boundaries A place where two plates slip past each other, moving in opposite directions.

Chapter 6 Earthquakes

What forces cause the movement of Earth’s plates? Big Question

The force that causes the movement of Earth’s plates is… Stress A force that acts on rock to change its shape or volume. Types of Stress Tension pulls on the crust, stretching rock so that it becomes thinner in the middle. Compression squeezes rock until it folds or breaks. Shearing pushes a mass of rock in two opposite directions.

The build up of stress creates a fault. Most faults occur along plate boundaries, where the forces of plate motion push or pull the crust so much that the crust breaks. Types: Normal faults The fault is at an angle so one block of rock lies above the fault while the other block lies below the fault. Reverse faults The same structure as a normal fault but each side moves toward one another instead of away. Strike – Slip faults The rocks on either side of the fault slip past each other sideways or up and down.

How does energy travel through Earth during an Earthquake? Big Question

Energy travels through Earth during an Earthquake in waves. Seismic waves carry energy from an earthquake away from the focus, through Earth’s interior, and across the surface. P waves are seismic waves that compress and expand the ground like an accordion. S waves are seismic waves that vibrate from side to side as well as up and down. Surface waves move more slowly than P waves and S waves, but they can produce severe ground movements.

How do geologists measure Earthquakes? Big Question

Geologists measure Earthquakes using… The Mercalli Scale Rates earthquakes according to the level of damage at a given place. The Richter Scale A rating of an earthquake’s magnitude based on the size of the earthquake’s seismic waves. The Moment Magnitude Scale A rating system that estimates the total energy released by an earthquake.

Monitoring Earthquakes The Seismograph Seismic waves cause the seismograph’s drum to vibrate. But the suspended weight with the pen attached moves very little. Therefore, the pen stays in place and records the drum’s vibrations. The pattern of lines produced is called a seismogram.

Instruments that Monitor Faults Tiltmeters Measures vertical movements. Creep Meters Measures horizontal movements. Laser-Ranging Device Measures horizontal movement. GPS Satellites Measures changes in elevation and tilt of the land as well as horizontal movements along a fault.

Causes of Earthquake Damage Shaking Liquefaction Aftershocks Tsunamis

Steps to Earthquake Safety Drop… Cover Hold Designing Safer Buildings Stronger More flexible Protecting Structures A base – isolated building is designed to reduce the amount of energy that reaches the building during and earthquake.

Chapter 7 Volcanoes

How are volcanoes related to plate tectonics? Big Question

Volcanoes are related to plate tectonics because… Volcanic belts form along the boundaries of Earth’s plates.

Boundaries At diverging boundaries volcanoes form along the mid-ocean ridges. Many volcanoes form at converging boundaries where oceanic plates return to the mantle. Hot spots are areas where material from deep within the mantle rises and then melts, forming magma.

Properties of Magma Physical and Chemical Each substance has a particular set of physical and chemical properties. These properties can be used to identify a substance or to predict how it will behave. Physical properties are characteristics of a substance that can be observed or measured without changing the composition of the substance EX – density, hardness, melting point, boiling point, magnetism Chemical properties are properties that produce a change in the composition of matter. EX – burn, combine, react

Properties of Magma Viscosity Temperature The physical property of liquids which describes the resistance of a liquid to flowing. The Viscosity of magma depends upon its silica content and temperature. Temperature Pahoehoe is fast-moving hot lava that has low viscosity. Aa is cooler and slower-moving lava.

How do volcanoes erupt? Big Question

Volcanoes erupt in… Different types of eruptions. Different stages of activity.

Magma reaches Earth’s surface When a volcano erupts, the force of the expanding gases pushes magma from the magma chamber through the pipe until it flows or explodes out of the vent.

Magma reaches Earth’s surface Magma Chamber Magma collects ina pocket Pipe Long tube in the ground that connects the magma chamber to Earth’s surface. Vent Molten rock and gas leave the volcano through an opening called a vent. Lava flow is the area covered by lava as it pours out of a vent. A crater is a bowl shaped area that may form at the top of a volcano around the central vent.

Kinds of Eruptions Quiet Eruptions Low silica magma Low viscosity Explosive Eruptions High in silica High viscosity A pyroclastic flow occurs when an explosive eruption hurls out a mixture of hot gases, ash, cinders, and bombs.

Stages of Volcanic Activity Active volcanoes are erupting or show signs of erupting in the near future Dormant volcanoes are expected to awaken in the future and become active. An extinct or dead volcano is unlikely to erupt again.

Landforms from Volcanoes Landforms from Lava and Ash Shield volcanoes are formed from a lava flow which builds a wide, gently sloping mountain. Cinder Cone Volcanoes Composite volcanoes are tall, cone-shaped mountains in which layers of lava alternate with layers of ash. Calderas are the holes left after the collapse of a volcano. Lava Plateaus Soil Landforms from Magma Volcanic necks form when magma hardens in a volcano’s pipe. A dike is formed from magma that forces itself across rock layers and hardens A sill is formed when magma squeezes between horizontal layers of rock. A batholith is a mass of rock formed when a large body of magma cools inside the crust. Dome Mountains