| A | B |
|---|
| Pangaea. | All of the continents were once connected as one large landmass |
| Continents have moved slowly to their current position. | continental drift |
| What evidence reveals a continental drift? | puzzlelike fit of continents, similar fossils and rocks on different continents |
| What the continental drift accepted at first? | no |
| Using ___waves, scientists discovered a system of underwater mountain ranges call the mid-ocean ridges in many oceans. | sound |
| Harry Hess’ theory of seafloor spreading | hot, less dense material below Earth's crust rises toward the surface at the mid-ocean ridge, it cools, contracts, and becomes denser. This denser, colder seafloor sinks, helping to form the ridge |
| Evidence for seafloor spreading | youngest rocks are located at mid-ocean ridges and reversals of earth's magnetic field |
| How could seafloor spreading related to continental drifting? | If the seafloor is constantly spreading apart and moving, it will affect and move the continents as well |
| According to the theory of __ __, the Earth’s crust and part of the upper mantle are broken into sections | plate tectonics |
| A large section of Earth’s oceanic or continental crust and rigid upper mantle that moves around on the asthenosphere | plates |
| Lithosphere. | The plates and the upper mantle- about 100 km thick |
| Asthenosphere. | The plastic like layer below the lithosphere |
| Divergent boundaries. | plates moving apart |
| Plate boundary that occurs when two plates slide past one another | convergent boundaries |
| The cycle of heating, rising, cooling and sinking of material inside Earth- warm air rises | convection current |
| Area where an oceanic plate goes down into the mantle | subduction zone |
| Crust. | Outermost layer of Earth’s surface |
| Largest layer of Earth’s surface composed of mostly silicon, oxygen, magnesium, and iron | mantle |
| Outer most layer of the Earth under the ocean | oceanic crust |
| How did the Glomar Challenger’s scientists contribute? | They found samples of rocks from different locations |
