Earth Science Layers of the Earth

The Earth’s Layers Layers

Lithosphere The top part of the layer is the Earth’s crust. The outermost layer of the earth known as the “rock sphere” that we live on. It is divided into pieces called tectonic plates

Asthenosphere The soft layer of the mantle below the lithoshphere. Tectonic plates move above this layer.

Outer Core The liquid layer below the earth’s mantle. This layer surrounds the inner core.

Inner Core The solid, dense center of our planet. It is about 6,374 km. beneath the earth’s surface.

“Plate tectonics” Theory: u explains motion/behavior of Earth’s lithosphere uMoves a few centimeters a year u explains volcanoes, mountain building and earthquakes ustiff lithosphere floats on top of weak asthenosphere

Plate tectonics u about a dozen or so plates

Modern measurements Supporting evidence

What drives the plate movement? EARTH is a Heat Engine EARTH is a Heat Engine

Tectonic Plates The place where two tectonic plates meet is called a plate boundary.

Plate Boundaries l divergent boundaries l convergent boundaries l transform fault boundaries 3 types

h2/content/chapter_4/animations.asphttp:// h2/content/chapter_4/animations.asp

2) Plate boundaries PLATETECTONICS l Divergent boundaries Mostly mid-ocean ridges (seafloor spreading) Typical spreading rates ~ 5 cm/year As oceanic moves away from ridge, it cools, & becomes denser Also found where continents break apart Example: Red Sea and East African Rift

Mid Ocean Ridges

Continents Break Apart – Rift Valley

2) Plate boundaries PLATETECTONICS l Divergent boundaries Also found where continents break apart Example: Red Sea imations/sea_floor_spreading.htm

Red Sea (looking southeast) 2) Plate boundaries PLATETECTONICS

PLATETECTONICS l Divergent boundaries Continents breaking apart Example: East African Rift Red triangles show the active volcanoes and the Afar Triangle (shaded, center)

Divergent Plate Boundaries

2) Plate boundaries PLATETECTONICS

l Convergent boundaries Subduction zones ocean-continent ocean-ocean continent-continent - Volcanoes Examples: Mount St. Helens - Volcanic island arcs Examples: Marianas, Aleutians, Hawaii - Mountain Building Examples: Himalayas, Alps, Appalachians Convergent Plate boundaries Convergent Plate boundaries

continental crust and continental crust Mountain building

Oceanic and oceanic crust DEEPEST Trenches and Island Arcs Oceanic crust

Continental Crust and Oceanic Crust Trenches and explosive volcanoes Molten rock Oceanic crust Continental crust volcano SUBDUCTION ZONE

Mountains Volcanoes, trenches & earthquakes

l Transform fault boundaries Strike-slip faulting Plates slide past each other: no production/destruction of material 2) Plate boundaries PLATETECTONICS

STRESS Stress occurs at plate boundaries. Stress causes rock to change shape or deform (deformation) Types of Stress: Type of boundary –Compression –Tension –Shearing convergent divergent transform

Stress Causes Deformation Deformation Bends and Breaks Rock

If you bump your bike into a large rock two things can happen. The metal can either bend or snap.

Stress Cause - Compression Effect: Folding Folding- When rock layers bend because of stress on the earth’s crust. The types of folding are:

Folding Anticline- Arch shape folds in the earths’ crust. Syncline- Trough shaped fold in a rock. pushing

Monocline Monocline – simplest - involves a slight bend on one side

Anticline

Folding Syncline- Trough shaped fold in a rock.

Syncline

Monocline Monocline – simplest - involves a slight bend on one side

Monocline

Tectonic Plates The place where two tectonic plates meet is called a plate boundary. (When there is enough pressure that builds up on the rocks’ edges and earthquakes can occur).earthquakes Earthquake Facts

Earthquake Animation

Tectonic Forces Faulting- Stress that causes rocks to break Faults slide past each other. The types of faulting are: - normal fault - reverse fault - strike-slip fault

Fault Type #1: Normal Fault Cause: Tension/ Divergent movement Normal FaultsNormal Faults- Effect: The hanging wall moves down, relative to the footwall. Normal because of the pull of gravity.

Normal Fault

Fault Type #2: Reverse Fault Cause: Compression/ Convergent Movement Reverse Fault- Effect: The hanging wall moves up relative to the footwall.

Reverse Fault

Strike-Slip Fault Cause: shearing/ crosswise movement Strike-slip FaultsStrike-slip Faults- Effect: When opposing forces cause rock to break and move horizontally.

Strike Slip Fault

Strike Slip Fault San Andreas Fault

Mountain Building Cause: Compression Effect: Uplift – crust is raised to higher elevation US Geological Survey scientist Chris Newhall attaches a tape measure to a cliff on Bubuin Island. Activity from nearby Volcano Island has lifted Bubuin by 15 centimeters

Grand Canyon

Folded Mountains In a folded mountain range, the rock layers are folded up.

Folded Mountains Fault-Block Folded Volcanic

Folded Mountains Sierra Nevada

Folded Mountains Appalachian

Folded Mountains Appalachian Mountains

Fault-BlockMountains Fault-Block

Fault- Block Mountians Rock layers are tilted up and can have sharp jagged peaks.

Fault-Block Mountains Grand Tetons from Jackson Lake Lodge (WY) are examples of fault block mountains.

Fault Block Mountain

Fault-Block Mountains Big Bend Texas

Volcanic Mountains Volcanic mountains are often cone shaped, and form along convergent boundaries. Also forms along the divergent sea floor spreading

Volcanic Mountains

Mt. Ranier, Washington

Volcanic Mountains Mt. St. Helens, Washington

Volcanic Mountains Mt. Shasta, California

Volcanic Mountains Volcanic mountains of Guatemala make up part of the Pacific's "Ring of Fire".

Popocatepetl, Mexico. December 12, 2007 this volcano spewed lava and ash two miles high.

Volcanic Mountains Mt. St. Helens- Live

On May 18, 1980, Mount St. Helens violently erupted. For 2 months the volcano showed signs that it was waking up from its 123-year sleep. Earthquakes beneath the mountain increased. Steam and ash erupted. And a "bulge" grew on the mountain's steep north side. All these warning signs signaled that magma was moving upward inside the volcano.

US Volcanoes Cascade Range Volcanoes Major West Coast Volcanoes Hawaii Volcano Map