Chapter 32

Standards Earth Science Standards Dynamic Earth Processes : 3d, e, f Objectives: 1.Students will define key terms for chapter Students will learn the layers of the Earth 3.Students will know why and how earthquakes occur and the scales used to measure their intense magnitude.

Key Terms Secondary waves Core Asthenosphere Crust Syncline Fault Primary waves

Key terms Mantle Lithosphere Anticline

Secondary waves A transverse body wave; cannot travel through liquids.

Core The central layer in the Earth’s interior, divided into outer liquid core and inner solid core.

Asthenosphere A subdivision of the upper mantle situated below lithosphere, a zone of plastic-like, easily deformed rock.

Crust The Earth’s outermost layer.

Syncline A fold in the strata that has relatively young rocks at its core.

Fault A fracture along which visible movement can be detected on one side relative to the other.

Primary waves (p-wave) A longitudinal body wave; travels through all material and is the fastest wave.

Mantle The middle layer of the Earth’s interior, between the crust and core.

Lithosphere The entire crust plus the portion of the mantle above the asthenosphere.

Anticline A fold in strata that has relatively old rocks at its core, with rock age decreases as you move horizontally.

Chapter 32 Notes What’s inside Earth? To answer this question scientist study seismic waves produced by earthquakes. Three layers make up Earth’s Interior: The crust The mantle The core Each layer has its own conditions and materials.

The Crust Is a layer of rock that forms Earth’s outer skin. It includes both dry land and the ocean floor. The crust beneath the ocean, called oceanic crust, consists mostly of basalt, a dark, dense rock with a fine texture. The crust that forms continents, called continental crust, consists mostly of granite rock, larger crystals than basalt and is not as dense.

Mantle Below the crust. A layer of hot rock. Crust and upper mantle form a rigid layer called the lithosphere. Temperature and pressure in mantle increase with depth. Pressure is the force pushing on a surface or area.

Mantle The increased heat and pressure make the part of the mantle just beneath the lithosphere somewhat soft. This soft layer is the asthenosphere. Lithosphere floats on top of the asthenosphere. The rest of the mantle down to the core is solid.

Core The Earth’s core consists of two parts. Both parts are made up of the metals iron and nickel. The outer core is a layer of molten metal that surrounds the inner core. The inner core is a dense ball of solid metal. Currents in the liquid outer core force the solid inner core to spin at a slightly faster rate than the spinning of the whole Earth. This movement creates the Earth’s magnetic field.

Chapter 32.1 All earthquakes create waves that travel through the Earth’s interior. Earthquake waves = seismic waves A waves speed depends on the medium it travels through. During an earthquake, energy is released into the Earth’s interior and radiates in all directions, and travels to the surface in the form of seismic waves.

Seismic waves reflect and refract from surfaces. Geologist use seismic waves like doctors use ultrasound to scan the insides of a body. Two types of seismic waves: body waves (p- waves) and surface waves (s-waves).

Seismic waves causes the ground to shake and move. The ground movement is recorded on a seismograph. Seismic waves P-wave S-wave Rayleigh waves Love waves

Rayleigh waves move up and down in motion Love waves move side- to- side, whiplike motion. Both surface waves Both move slower than p & s-waves Last to be registered on a seismograph

P-waves Move longitudinally Compress and expand rock Move out in all directions from their source Fastest; reach seismograph first Can travel through any material: solid, liquid, etc.

S-waves Move transverse; up/down, side to side Slower, second to reach seismograph Can’t move through fluids; only through solids

Chapter 32.3 Folds, faults, and Earthquakes – The slow-moving mantle causes the lithospheric (tectonic plates) to move slowly, but constantly. – This movement causes stress on the plates.

Rock Folds and Expression of Compression Force The slow-moving mantle causes the lithospheric (tectonic plates) to move slowly, but constantly. This movement causes stress on the plates.

Rock Folds and Expression of Compression Force Compression causes rocks to buckle and fold. Anticline: push up folds Syncline: folds pushed downwards – See diagram page 577

Faults Are Made by the Forces of Tension or Compression 3 Types of Faults – Compression = reverse fault – Tension= normal fault – Horizontal motion= strike-slip fault

Reverse fault

Normal Fault

Strike-slip Fault