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Sea-Floor Spreading
| Question | Answer |
|---|---|
| What is the typical climate deep in the ocean? What is a place unlike this? | Freezing and barely any light. A place unlike this is the East Pacific Rise |
| Why is the East Pacific Rise warm? | Because the water there sinks through the cracks, or events, and the crust. The water is heated by contact with hot material from the mantle. The hot water then spurts back into the ocean. |
| What are in the hot Waters? | Bizarre underwater creatures |
| What is the East Pacific Rise? | It is a mid-ocean ridge that whines beneath earth's oceans |
| What do scientists use to map mid-ocean ridges? | Sonar |
| What is sonar? What can scientists conclude from this? | A device that bounces sound waves off underwater objects and then record The Echoes of these sound waves. This can conclude from this what is the depth of the ocean of that spot. |
| What do mid ocean ridges look like? | They curve like the seam of a baseball along the seafloor |
| What do mid ocean ridges have to do with mountains? | Mid-ocean ridges are a system of mountain chains on the bottom of the ocean |
| Is it possible for a mid-ocean range to poke above the surface of the water? What is an example? | Yes, for example Iceland |
| Does sea floor spreading only happen once? | No, seafloor spreading continually adds new material to the ocean floor |
| What are the consequences of seafloor spreading? | And seafloor spreading, the seafloor spreads apart along both sides of a mid-ocean ridge as new crust is added. As a result the Ocean Floors move like conveyor belts, carrying the continents along with them |
| What happens along a mid-ocean ridge when molten material beneath the surface Rises and erupts? | Older rock moves outward on both sides of the ridge. As molten material cools, it forms a strip of solid rock in the center of the Ridge. When more molten material flows into the crack it forms a new strip of Rock |
| What are deep ocean trenches? | Deep depressions in the deepest parts of the ocean |
| How deep is the deepest to deep ocean trench? What is its name? | The Challenger Deep in Mariana Trench is about 11,000 meters deep |
| Do magnets stick to All Metals? Which metals? | No, they stick to mostly iron,nickel, and coblat |
| What is attraction? | The force that sticks iron to magnets |
| What does repulsion mean? | To push a part |
| What are the rules for repulsion and attraction for magnets? | Opposite poles of a magnet are attracted to each other and like poles of a magnet repel each other |
| What are magnets poles called? | North and South |
| What are the lines of force on a magnet? | Where the magnets force is strongest |
| Can other materials become a magnetized? What is this called? | Whatever magnets are strongly attracted to are also materials that can be magnetized. Materials with these properties are called ferromagnetic |
| Can you separate a North Pole from a South Pole to get a piece which is only a North Pole or which is just a South Pole? | No, even the tiniest pieces broken off a magnet have a North and South Pole |
| Are compasses magnets? | Yes |
| How do we know that Earth has a magnetic field? | Because compasses are magnets and it is always the same side of the needle that eventually will Point North this means that something is pulling on the compass needle |
| When is a time that compasses will not Point towards Earth's magnetic field? | If there is another magnetic fields close by which exerts a stronger pull in another Direction |
| Where is Earth's magnetic field stronger and weaker? | It is stronger closer to the magnetic poles and weaker around the equator |
| What is evidence for seafloor spreading? | 1. Eruptions of molten material 2. Magnetic stripes in the rock of the ocean floor 3. Ages of the rocks themselves |
| What has happened to Earth's magnetic poles over the years? | They have reversed |
| When was the last reversal of Earth's magnetic poles? | About 780,000 years ago |
| How much do Earth's magnetic poles move per year? What will it look like? | Earth's magnetic poles move about 40 kilometers per year. It is a gradual change and we don't know what it will look like. |
| What did scientists find out about rock that makes up the ocean floor?What does this show? | That the rock that makes up the ocean floor lies in a pattern of magnetized stripes. These stripes hold a record of reversals in Earth's magnetic field |
| What it is in the rock of the ocean floor? | Iron |
| What happens when the rock with iron cools and hardens? | The iron bit inside line up in the direction of Earth's magnetic poles. This locks the iron bits and place, giving the Rocks a permanent magnetic memory |
| How can Iron become a magnet? | Due to an electric current |
| How do convection currents cause the Earth's magnetic field? | We think that the convection current of the hot liquid iron and nickel cause electric currents and the electric currents cause Earth's magnetic field |
| Generally, does the ocean floor keep spreading? | No, but instead plunges into deep water Canyons called the deep ocean trenches |
| What occurs at deep ocean trenches? | In a process taking tens of millions of years, part of the ocean floor sinks back into the mantle at deep ocean trenches. This process is called subduction |
| What happens as subduction occurs? | Crest closer to a mid-ocean ridge moves away and toward a deep ocean trench. Seafloor spreading and subduction work together |
| Do subduction and seafloor spreading make any change to the ocean? | Yes, they can change the size and shape of the oceans |
| About how often is the ocean floor renewed? | About every 200 million years |
| Are oceans shrinking or growing because of subduction and seafloor spreading? | Both, the Pacific Ocean is shrinking and the Atlantic Ocean is growing |
| Why is the Pacific Ocean shrinking? | Subduction through the many trenches that ring the ocean, is occurring faster than new crust can be added |
| Why is the Atlantic Ocean growing? | Because the other few short trenches, the whole ocean gets wider because as the ocean floor spreads, the continents along its Edges also move |
| Where is the North Magnetic Pole? | Actually is a South Pole of Earth's magnetic field. |
| **What is the definition of seafloor spreading?** | Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge on either side of the ridge. |
| How did we know about mid-ocean ridges? | At some point we mapped the ocean floor |
| How are the ages of rocks on the ocean floor evidence for sea-floor spreading? | The further away from the ridge, the older are the rocks. The oldest rocks on the ocean floor are the farthest away from the mid-ocean ridge and are about 200 million. |
| About how old are rocks on continents? | Rocks on the continents are over 2 billion year old. This is because there are no deep-ocean trenches on land. |
| How are eruptions from mid-ocean ridges evidence for sea-floor spreading? | We found newly formed rocks formed from lava through rapidly cooling. |
| **What are magnetic stripes on the ocean floor?** | The ocean floor has magnetic stripes which are are parallel to the mid-ocean ridges. The iron bits in neighboring stripes are magnetized but the polarity is reversed. |
| Why are some magnetic stripes wider and some thinner? | How long the magnetic field was polarized one way or the other affects the thin and thickness of magnetic stripes. |
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