Earth’s Interior

Earth’s Interior

1. Direct evidence – rock samples from up to 12km deep

2. Indirect evidence – seismic waves (waves that travel through the earth during earthquakes)

wps.prenhall.com

Temperature and Pressure

Temperature• Deeper you go the warmer it is• After 20 meters, every 40 meters you descend the

temperature rises 1 degree Celsius• High temperature results from the formation of the

planets and radioactive substances releasing energyPressure• The deeper you go, the higher or greater the

pressure

Layers of the Earth

myschoolhouse.com

Layers of the Earth1. Crust: layer of solid rock that includes both

dry land and ocean floora) oceanic crust – crust beneath the ocean, made of basalt rockhttp://volcanoes.usgs.gov/images/pglossary/basalt.php

b) continental crust – the crust that forms the continents (land), made of granite

nwnature.net beg.utexas.edu

Layers of the Earth

2. Mantle: below the crust, very hot and solid, 3,000 km thicka) lithosphere: uppermost mantle and crust, pushed together, 100km thickb) asthenosphere: soft layer of the mantle (it can bend like plastic) but is still solid, the lithosphere floats on top of this layer, 2,767km thickc) lower mantle: beneath the asthenosphere, solid layer that extends to the core

Layers of the Earth3. Core – two parts made of iron and nickel

a) outer core: layer of molten metal that surrounds the inner core, this layer is liquidb) inner core: solid metal due to extreme pressure.

- The movement in the core creates Earth’s magnetic field

Convection and the MantleTypes of Heat Transfer

1. Radiation: transfer of energy through space, no direct contact needed. Example: sun blacktop or heat from fire

2. Conduction: heat transfer within a material or between materials that are touching (soup spoon in soup pot)

3. Convection: heat transfer by the movement of currents within a fluid (bounce off one another and heat up, example: teapot).- caused by differences in temperature and density within a fluid

Density = mass/volume

Density: amount of mass in a given volume of a substance.

- as gas or liquid is heated, the particles move faster and take up more space, decreasing it’s density

- as a gas cools, the particles slow and settle closer, increasing it’s density

Convection currents: the flow that transfers heat within a fluid

- Gravity and density put these currents in motion

* Convection currents occur in the mantle and outer core *

physics.arizona.edu

Continental Drift• It states: that all the continents were once joined

together in a single landmass and have since drifted apart• Alfred Wegener responsible for this idea• When all continents were joined together it was called

Pangaea• Wegener used evidence from land features, fossils, and

climate change to prove this theory (it was NOT accepted)Land: used mountains and features on the continentsFossils: any trace of an ancient organism preserved in rockClimate change: as a continent moves toward the equator,

it becomes warmer (coal was found in Antarctica)

Sea-floor Spreading• Sea-floor spreads apart along both sides

of a mid-ocean ridge as new crust is added

• Ocean (sea) floor moves like a conveyor belt, carrying the continents along with them

123rf.com

Mid-ocean ridge: a mountain chain at the bottom of the ocean where the new ocean is produced.

- The new ocean floor forms when lava is erupted onto the ocean floor.

http://geomaps.wr.usgs.gov/parks/animate/index.html

Evidence of Sea-Floor spreadingHarry Hess’s theory

1. Molten material: tube shaped rocks from molten material hardening quickly

2. Magnetic stripes: pattern of magnetized stripes (iron in the rock), when rock cools

3. Drilling samples: rock samples farther away from mid-ocean ridge the older the rock was

xtimeline.com

Subduction and TrenchesDeep ocean trench: deep underwater

canyon that bends downward into the oceanic crust

Subduction: when the ocean floor sinks beneath a deep ocean trench and back into the mantle

How has this changed our oceans?

• Pacific Ocean is shrinking because the deep ocean trenches are too big

• Atlantic Ocean is getting bigger because it only has a few short trenches

Plate TectonicsPlates: broken sections in the lithosphere

that look like cracksPlate tectonics: pieces of Earth’s lithosphere

are in slow, constant motion, driven by convection currents in the mantle

- This theory explains the formation, movement, and subduction of Earth’s plates

- As plates move, they collide, pull apart, or grind past one another

Plate Boundaries

Divergent boundary: place where 2 plates move apart. Example – Great Rift Valley or Grand Canyon

- Occur along mid-ocean ridges- Forms a rift valley (deep valley on land)

cotf.edu

Convergent BoundaryDefinition: place where two plates come

together or collide

- The more dense (heavier) plate will sink below the other plate (subduction)

- On land this creates mountain ranges

cotf.edu

Transform Boundary

Definition: place where two plates slip past one another in opposite directions

*Earthquakes occur here*gweaver.net

Different Types of Boundaries

http://pubs.usgs.gov/gip/dynamic/understanding.html

Divergent Boundary – Arabian and African Plates

Arabian Plate

African PlateRed Sea

Divergent Boundary – Iceland

http://pubs.usgs.gov/gip/dynamic/understanding.html

Divergent Boundary - Oceanic

http://www.geology.com

Divergent Boundary - Continental

http://www.geology.com

Convergent Boundary – Indian and Eurasian Plates

Indian Plate

Eurasian Plate

Convergent Boundary – Oceanic & Continental

http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

Convergent Boundary – Oceanic & Oceanic

http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

NOTE – PLATES ARE REVERSED

Convergent Boundaries - Continental

http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

Transform Boundary – San Andreas Fault

www.geology.com

How to calculate plate movement

Rate = Distance/TimeExample: A plate takes 2 million years to

move 156km. Calculate the rate at which the plate moved.

156km/2,000,000yrs = 7.8cm/year