If you were lost, how could a dog help?

A new study says that dogs choose the direction they relieve themselves based on our planet's magnetic field.

Inside the EarthHow do scientists know?

Earth in General

3 Layers• Crust• Mantle• Core

Diameter• 12,750 km

Cross Section Diagram

Overview of the Crust• Solid Basalt and Granite• 5-100 km thick• Coolest in temperature• Least dense

2.2-2.9 g/cm3

• Like the “shell of egg,” is brittle and can break

• Layer we live on

What is the difference between sediment and bedrock?

Sediment is Smaller pieces of broken rock mixed with organic

material and remains

Bedrock is rockunderneath the accumulated

sediment

Overview of Crust (continued)• Major changes

Plate Tectonics• Minor changes

Weathering & erosionDeposition of sediments

• Two types of CrustOceanic (very dense, made

of basalt)Continental (less dense,

made of granite)

Example of minor change& a bit of New Hampshire folklore

For A. Cleary

Oceanic and Continental Crust

Oceanic Crust• Mainly Basalt•Thinnest part of crust ~ 5 km thick•Density 3.0 g/cm3

• Ocean puddles on top• Youngest part of crust, new crust is made here

Continental Crust • Mainly Granite•Thickness varies but ~ 30 km thick• 100 km thick under Himalayans Mts.•Density 2.7 g/cm3

• Oldest part of crust

Overview of the Mantle• Like “white” of egg• Hot layer of semi solid rock • Contains more iron, magnesium and calcium than crust • Hotter & denser… temp and pressure increase w/depth• ~2900 km thick• Density 3.4 – 5.6 g/cm3

• Multiple layers which have different densities

Upper Mantle and Lower MantleUpper Mantle

• ~720 km thick• Density 3.4 – 4.4 g/cm3

• ~1480 C, rock is near melting

• Magma from some volcanoes can originate here

Lower Mantle• ~2170 km thick• Density 4.4 – 5.6 g/cm3

• ~ 2600 C• Higher level of magnesium

& silicon oxides

Overview of the Core• Mostly iron & nickel, metal• Core is not rock or fire• ~3300 km thick• Twice as dense as mantle

Outer Core

• Liquid nickel and iron• 2200 km thick• Density 9.9 – 12.2 g/cm3

• ~3800 C

Inner Core

• Solid nickel and iron• 1250 km thick• Density 12.2 – 13.1 g/cm3• ~4300 C

The inner core is solid but hotter than the outer core; why?

Where does the core get its heat?

• Chunks of material collided and stayed together, (Heat from these collisions can be on the order of 10,000 kelvins about 18,000 degrees Fahrenheit).

• Friction, when denser core material sinks• Decay of radioactive elements, mostly

uranium and thorium according to physicists.

Earth’s Layers

How are the earth’s layers similar to an egg?

• Shell=crust• Egg white=mantle• Yolk=core

Interactions between Layers Lithosphere

• Includes crust and solid, uppermost part of the mantle

•Broken into about 19 pieces, these pieces are called “PLATES”

•The plates move on top of the Asthenosphere (which is a thin layer of the upper mantle)

Interactions between Layers

Asthenosphere • Beneath the lithosphere, in the mantle, lies a soft, relatively weak region of rock that flows slowly (like soft plastic or hot asphalt)

•Convection Currents that drive the movement of plates happen in the Asthenosphere

Vocabulary expected to knowSphere – shaped like a ballHemisphere – half of a sphereInterior – insideExterior – outsideCross Section – diagram that shows a piece “cut

out,” so you can see the insideMolten – melted, usually referring to material

that melts at very HIGH temperature

Vocabulary expected to know

*Lava – melted rock touching atmosphere*Magma – melted rock below the crustTectonic Plates – broken pieces of the

lithosphere

Tectonic Plates• Earth’s crust is broken into about 19 pieces• These plates move on top of the

asthenosphere (thin layer of the upper mantle)