| A | B |
|---|
| Pacific Ocean | the largest of the Earth's oceans |
| satellite | how scientists map the ocean floor now |
| What pulls on the Earth's oceans to cause high and low tides? | the moon's gravity |
| What causes water to rise and fall on the oceans' surface? | wind |
| When a wave breaks on the shore, which part keeps going? | the top part |
| What occurs when huge amounts of sand are moved from place to place? | a sandbar |
| Why was the use of weights on a rope unreliable to measure the ocean depth? | The rope might be too short or the rope may have hit another object to make the sailor think he had hit bottom. |
| What happens to the food chain during El Nino? | The food chain is disrupted because fish either die or move to colder waters. |
| continental shelf | the shallow part of the ocean at the edge of the continents |
| ocean basin | the floor of the deep ocean (the bottom) |
| continental slope | the edge of the continental shelf that extends steeply downward to the ocean floor |
| trench | a deep, narrow valley in the ocean floor; compared to a valley on land |
| ridge | the highest part of a chain of underwater mountains. Like a mountain on the land |
| current | a riverlike flow of water in the ocean. Temperatures are different from water around the current. Currents move at different speeds. |
| tide | the rise and fall of the surface level of the ocean |
| wave | the up-and-down movement of ocean water caused by the wind |
| What determines the direction of ocean currents on the surface of the ocean? | The direction of the ocean currents is determined by the direction of the wind and the rotation of the Earth. |
| What effects can El Nino have on weather? | Severe storms and droughts have been caused by El Nino. |
| How many times a day do tides usually occur along many parts of the ocean shore? | 2 times a day |
| What causes tides? | Tides are caused by the pull of the moon on the ocean water. |
| How do waves affect the shoreline of the earth? | Waves crashing against the shore wear away or erode the sediments and rocks along the shoreline. They also carry sand to other places. |
| What do scientists use today to check out the bottom of the ocean floor? | Scientists use satellite and radar. |
| What happens to the bottom part of the wave? | The bottom part of the wave is slowed down by the ocean floor. |
| What is El Nino? | El Nino is a huge pool of warm water that spreads eastward across the Pacific Ocean every few years. |
| What causes El Nino? | El Nino is caused by trade winds (steady winds) that don't blow as hard as usual. |
| What are the tides called? | Tides are called high tide and low tide |
| What causes tides? | Tides are caused by the pull of the moon on the ocean water. |
| How do waves affect the shoreline of the earth? | Waves cause erosion of beaches and rocks. Waves also create sandbars. |
| What did scientists use in the 1900's to measure the depth of the ocean? | Scientists used echoes/sounding. |
