Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Title: Volcanoes (BLR) Author: Emiliano Bermejo Black Mount St. Helens It was the morning of May 18, 1980. A powerful earthquake shook the mountains in the state of Washington. Seconds later, the top of Mount St. Helens exploded and slid away in a huge landslide. Powerful explosions ripped through the sliding rocks. Hot ash, gas, and whirling stream burst up and out of the mountain. The volcano was erupting. The blast shot out of the side of the mountaintop. It snapped huge trees like matchsticks. Everything in its path was destroyed. A huge cloud of ash and gas rapidly formed above the mountain. It blotted out the sun, turning morning into night. The cloud blew east across the United States. Within three days, ash from the volcano traveled all the way across the country from its source. Why Do Volcanoes Erupt? Long ago, ancient people told stories to explain why volcanoes erupted. But they didn’t know what really caused them. Scientists now know a lot more about our planet. Earth is made up of three layers. The top layer is called the crust. The crust is the layer we walk on. It is made up of rock. Below the crust is the mantle. This layer is very hot. It is so hot that some of the rock there actually melts. The melted rock is called magma. Deep inside the Earth is the core. It is made up of different metals. Earth’s crust is not all in one piece. It is actually made up of huge rock plates. These plates cover Earth like the pieces of a giant jigsaw puzzle. We can’t feel it, but these plates are always moving. In some places, the plates pull apart. In other places, the plates push together. When two plates pull apart, they can create an opening. Volcanoes happen when gases, hot ash, and melted rock push up from the mantle through these openings. The hot melted rock is called lava (LAH vuh) when it ours out of a volcano. The Dangers of Volcanoes Volcanoes are very destructive. Lava can be hotter than 1,000 degrees! It will instantly kill and destroy anything in its path. 3 16 29 38 49 61 62 75 84 97 110 123 130 134 145 158 162 177 190 207 219 233 249 262 276 286 297 310 324 329 333 345 354 4 Grade, Unit 3, Lesson 11 Title: Volcanoes (BLR) Author: Emiliano Bermejo Black Mount St. Helens It was the morning of May 18, 1980. A powerful earthquake shook the mountains in the state of Washington. Seconds later, the top of Mount St. Helens exploded and slid away in a huge landslide. Powerful explosions ripped through the sliding rocks. Hot ash, gas, and whirling stream burst up and out of the mountain. The volcano was erupting. The blast shot out of the side of the mountaintop. It snapped huge trees like matchsticks. Everything in its path was destroyed. A huge cloud of ash and gas rapidly formed above the mountain. It blotted out the sun, turning morning into night. The cloud blew east across the United States. Within three days, ash from the volcano traveled all the way across the country from its source. Why Do Volcanoes Erupt? Long ago, ancient people told stories to explain why volcanoes erupted. But they didn’t know what really caused them. Scientists now know a lot more about our planet. Earth is made up of three layers. The top layer is called the crust. The crust is the layer we walk on. It is made up of rock. Below the crust is the mantle. This layer is very hot. It is so hot that some of the rock there actually melts. The melted rock is called magma. Deep inside the Earth is the core. It is made up of different metals. Earth’s crust is not all in one piece. It is actually made up of huge rock plates. These plates cover Earth like the pieces of a giant jigsaw puzzle. We can’t feel it, but these plates are always moving. In some places, the plates pull apart. In other places, the plates push together. When two plates pull apart, they can create an opening. Volcanoes happen when gases, hot ash, and melted rock push up from the mantle through these openings. The hot melted rock is called lava (LAH vuh) when it ours out of a volcano. The Dangers of Volcanoes Volcanoes are very destructive. Lava can be hotter than 1,000 degrees! It will instantly kill and destroy anything in its path. 4 Grade, Unit 3, Lesson 11 Title: The Big, Dangerous Wave (ELLR) Author: Gary Miller It was early in the morning on December 26, 2004. The Indian Ocean was very calm. But at the bottom of the sea, a big piece of the sea floor suddenly moved. The movement caused a big earthquake. The earthquake registered, or was measured, at 9.0 on the Richter scale. The Richter scale is the measurement scientists use to tell others how strong an earthquake is. As the sea floor moved, it also moved the water above it. This movement caused a huge wave, which moved away in all directions. This big, dangerous wave was called a tsunami (Soo NAM ee). When the wave finally reached land, it caused a lot of damage. A Big, Dangerous Wave What is a tsunami? It is not an ordinary wave. Wind and tides are the source, or cause, of most ocean waves. When wind blows along the top of the ocean, it causes waves. The tides cause the ocean waves to move, pulling water toward the shore, and then pulling it away. This causes waves, too. A tsunami is different. It is a big, dangerous wave caused by a strong movement of land into or below the sea. Landslides can cause tsunamis. Volcanoes can cause tsunamis, too. But most tsunamis care caused by earthquakes. It Starts with an Earthquake The outside of the Earth is made up of big pieces of rock called tectonic plates. These plates are like big puzzle pieces, except they move. Sometimes two plates try to move past each other. When they do, the plates slip quickly. When this slipping happens, the ground above the plates moves. Sometimes the group moves so little people can barely feel it. Sometimes it moves a lot, causing the ground under people’s feet to shake a lot. This is called an earthquake. When an earthquake happens beneath the ocean, the land on the sea floor moves. The water above the sea floor moves, too. How a Tsunami Happens To understand how a tsunami is made, look carefully at the picture. As one part of the sea floor moves up, the water above it moves up, too. At the same time, another part of the sea floor drops. The water above it drops, too. 13 30 40 53 65 66 79 91 104 113 117 133 146 159 171 173 187 199 210 211 216 231 242 255 258 268 281 296 299 311 321 325 338 355 370 371 4 Grade, Unit 3, Lesson 11 Title: The Big, Dangerous Wave (ELLR) Author: Gary Miller It was early in the morning on December 26, 2004. The Indian Ocean was very calm. But at the bottom of the sea, a big piece of the sea floor suddenly moved. The movement caused a big earthquake. The earthquake registered, or was measured, at 9.0 on the Richter scale. The Richter scale is the measurement scientists use to tell others how strong an earthquake is. As the sea floor moved, it also moved the water above it. This movement caused a huge wave, which moved away in all directions. This big, dangerous wave was called a tsunami (Soo NAM ee). When the wave finally reached land, it caused a lot of damage. A Big, Dangerous Wave What is a tsunami? It is not an ordinary wave. Wind and tides are the source, or cause, of most ocean waves. When wind blows along the top of the ocean, it causes waves. The tides cause the ocean waves to move, pulling water toward the shore, and then pulling it away. This causes waves, too. A tsunami is different. It is a big, dangerous wave caused by a strong movement of land into or below the sea. Landslides can cause tsunamis. Volcanoes can cause tsunamis, too. But most tsunamis care caused by earthquakes. It Starts with an Earthquake The outside of the Earth is made up of big pieces of rock called tectonic plates. These plates are like big puzzle pieces, except they move. Sometimes two plates try to move past each other. When they do, the plates slip quickly. When this slipping happens, the ground above the plates moves. Sometimes the group moves so little people can barely feel it. Sometimes it moves a lot, causing the ground under people’s feet to shake a lot. This is called an earthquake. When an earthquake happens beneath the ocean, the land on the sea floor moves. The water above the sea floor moves, too. How a Tsunami Happens To understand how a tsunami is made, look carefully at the picture. As one part of the sea floor moves up, the water above it moves up, too. At the same time, another part of the sea floor drops. The water above it drops, too. 13 30 40 53 65 66 79 91 104 113 117 133 146 159 171 173 187 199 210 211 216 231 242 255 258 268 281 296 299 311 321 325 338 355 370 371 4 Grade, Unit 3, Lesson 11