What’s inside the Earth. Is there really another world at the center What’s inside the Earth? Is there really another world at the center? What is the energy for surface features?

Our Dynamic Earth Earth is constantly changing How do we know it’s dynamic?? Earthquakes (and tsunamis) Volcanic eruptions Surface Features: Mountain Ranges; Mid-Ocean Ridges; Deep-Sea Trenches

Topography of the Ocean Floor

Topography of the Ocean Floor Mid-Ocean Ridge

Topography of the Ocean Floor Deep-sea Trench Mid-Ocean Ridge

Topography of the Ocean Floor Deep-sea Trench Mid-Ocean Ridge Island Chain

Elevated Continents

Submerged Ocean Basins Elevated Continents Submerged Ocean Basins

Questions: How are the ocean basins formed? How permanent are these features? What is the age of the ocean floor? What’s the age of the continents? Why are the ocean basins deep and the continents high?

The Surface of the Earth 2 levels: elevated continents submerged ocean basins What causes these surface features? We must know what goes on inside the Earth

What’s going on inside the Earth?

Early Ideas Jules Verne

“Journey to the Center of the Earth” Entered in Iceland Exited in Italy

Pellucidar

Information about the Earth’s Interior comes from: Meteorites Volcanoes Seismic Waves (“sound images”) Tremendous pressure enormous heat (from natural radioactivity)

Meteor Crater (Arizona)

Willamette Meteorite Found 1902, in West Linn Largest in the U.S.A. Sold and now resides in NYC

Volcanoes E.g., Hawaiian “hotspot” Windows into the Earth Samples 200km down (e.g., diamonds!)

Seismic Waves Sound energy from earthquakes and large explosions

Marianas Trench  11 km deep. DEPTHS Top of Mantle 10 to 70 km (5 to 30 miles) Top of Core 2,900 km (2000 miles) Center of Earth 6,300 km (4,000 miles) Mt. Everest  9 km high. Marianas Trench  11 km deep.

How do we know what’s inside the Earth?

How do we know what’s inside the Earth? Direct Observations: Exposures on surface up from  50 km (30 miles) depth Drilling to  15 km (10 miles) Volcanic Material up from  200 km (120 miles) depth

How do we know what’s inside the Earth?

How do we know what’s inside the Earth? Indirect Observations: Magnetic Field Iron core. Gravity Field Densities: Crust: 2 - 3 g/cm3 Mantle: 3.3 - 5.8g/cm3 Core: 10.8 g/cm3 Earthquake Seismic Waves Physical state of crust, mantle, core.

Interior of Earth by Strength LITHOSPHERE rigid outer shell crust and upper mantle (~ 50 to 200 km thick) somewhat brittle, breakable cold (like butter out of fridge) ASTHENOSPHERE warmer, plastic layer under lithosphere mantle from ~ 150 to 700 km squishy, plastic warm (like softened butter) LOWER MANTLE Solid, but can flow over time! ~700 to 2900 km OUTER CORE liquid INNER CORE solid

Submerged Ocean Basins Elevated Continents Submerged Ocean Basins

Swimming Pool

Earth’s Mantle

Continental Crust Earth’s Mantle

Types of Crust Continental Crust 20 to 70 km (10 to 30 miles) thick. Composed of highly evolved rocks, like granite (igneous), and metamorphic rocks, squeezed and heated under mountain ranges

Continental Crust Earth’s Mantle

Oceanic Crust

Types of Crust Continental Crust Oceanic Crust It is less dense, but thicker than oceanic crust Oceanic Crust It is thinner, but more dense than continental crust, so it sits lower than continental crust. Composed of basalt (volcanic).

Thick, Buoyant Continental Crust

Thin, Less-Buoyant Oceanic Crust

Thick Continental Crust Floats Higher

Thick Continental Crust Floats Higher Thin Oceanic Crust Floats Lower

Mid-Atlantic Ridge

Water Fills in the Low Areas

And Hides Features on the Ocean Floor! Water Fills in the Low Areas

PLATE BOUNDARIES

PLATE TECTONICS Tectonics: From the Greek “tecton” builder “architect” The study of large features on Earth’s surface and the processes that formed them.

PLATE TECTONICS: Large features: continents, mountain ranges ocean basins and processes: earthquakes volcanic eruptions These are due to movement of plates of Earth’s outer shell. All resulting from mantle convection

Cracked Egg Shell!