Earth's Dynamic Interior

Crustal plate movement occurs because the Earth's mantle flows as a result of uneven heating inside the mantle. Convection cells are created by very hot material deep in the mantle rising, then cooling, sinking again, and then heating again and then repeating the cycle. This process occurs because of the energy generated by _________________ within the Earth.

• differences in densities
• solar radiation
• radioactive decay of elements
• plate convergence

Consider the layers of the Earth seen here. What layer would you find these elements?
46.6% Oxygen (O) 27.7% Silicon (Si) 8.1% Aluminum (Al) 5.0% Iron (Fe) 3.6% Calcium (Ca) 2.8% Sodium (Na) 2.6% Potassium (K) 2.1% Magnesium (Mg)

• atmosphere
• crust
• mantle
• core

Based on the model, what fact or facts would you select to support the hypothesis that the Earth is not homogenous (all the same) within? All BUT ONE is a supporting fact.

• The travel velocity of the two earthquake wave types is not the same: P-waves are faster than S-waves.
• The outer core is presumed to be liquid because it does not transmit shear (S) waves.
• All waves change direction (refract) when they pass through layers of different density. Seismic waves refract.
• The speed of the waves is modified at different locations within the Earth.

Inside the earth, near its core, there is a flowing mass of molten ____________ called the outer core. The movement of this liquid metal, both laterally and up and down, causes the earth's crust to shift, as part of the plate tectonics process.

• silver
• lava
• iron
• fire

ALL BUT ONE factor is believed to be the source of Earth's internal heat energy. That is

• gravitational contraction of Earth's interior.
• extraterrestrial impacts.
• radioactive decay of isotopes.
• convection cells.

The core is the deepest and hottest layer of the Earth. It is made almost entirely of metal. The core is made of two layers: the outer core, and the inner core. The inner core is made mostly of iron. The iron core is extremely hot—between 5,000 and 7,000 degrees Celsius and

• rises up through the other layers of Earth to become the magma of volcanoes.
• fluctuates between solid and liquid, depending on the temperature.
• the pressure there is so great that it cannot melt and it is solid.
• is a molten mass of magma, much like the mantle.

How are the crust and the inner core ALIKE?

• They both have the same temperature.
• They are both under the same pressure.
• They are both very close to the center of the Earth.
• They are both solid.

Earth's layers formed as result of differentiation. During differentiation, different zones of elements form layers and today we know these layers are made up of different elements. Certain elements sunk to the center while others collected near the surface. We might predict that the __________ elements, like iron and nickel, formed the core.

• first crystallized
• more dense
• least dense
• light weight

Which layer is broken up into several plates which "move and float very slowly? Their very slow motion is the cause of plate tectonics, a process associated with continental drift, earthquakes, volcanoes, and the formation of mountains.

•  lithosphere
•  asthenosphere
• outer core
• inner core

This layer of Earth is thought to be a solid, iron-rich zone.

• lithosphere
• mantle
• outer core
• inner core