Landforms

Unit Standards 5.E.3A.1 Construct how different landforms and surface features result from the location and movement of water on Earth’s surface through watersheds (drainage basins) and rivers. 5.E.3A.2 Develop and use models to describe and compare characteristics and locations of the landforms on continents with those on the ocean floor (including the continental self and slope, the mid ocean ridge, the rift zone, the trench, and the abyssal plain). 5.E.3B.1 Analyze and interpret data to describe and predict how natural processes (such as weathering, erosion, deposition, earthquakes, tsunamis, hurricanes, or storms) affect Earth’s surface.

What is a volcano? Volcano- a mountain that builds up around an opening in Earth’s crust.

What is a volcano? Eruption- when melted rock, gases, and pieces of rock are forced out of a volcano.

What is a volcano? A volcanic eruption can cause land to change suddenly.

What is a volcano? When some volcanoes erupt, gases are trapped in the magma (melted rock) come to the surface. The gases begin to escape.

What is a volcano? When the gases escape easily, there is a gentle eruption.

What is a volcano? When trapped gases build up pressure in magma, there can be an explosive eruption. That is the kind of eruption that happened at Mount St. Helens in May 1980.

What is a volcano? Magma is found deep below the Earth’s surface. Magma can rise up through a central opening in a volcano.

What is a volcano? Vent- the opening in a volcano

What is a volcano? Lava- magma that reaches Earth’s surface

What is a volcano? Lava can ooze slowly or quickly. When lava flows over Earth’s surface it cools and hardens. Over time it causes a mountain to form.

Where do volcanoes come from? Most volcanoes are located along faults.

Where do volcanoes come from? Where Earth’s plates move together, one plate can be pushed beneath another. The plate moving down melts and is changed to magma. Like heated air or water, magma rises. It rises up through the Earth’s crust to form volcanoes.

Where do volcanoes come from? Volcanoes also form when Earth’s plates move apart. They form along the edges of the spreading plates. These are called rift volcanoes. Most rift volcanoes form along the ocean floor.

Where do volcanoes come from? Sometimes volcanoes form where plates do not meet. An example is the Hawaiian Islands. These volcanic islands formed in the middle of the plate.

Where do volcanoes come from? Geologists think that their plate may move over a hot spot. As a plate moves over a hot spot, magma rises, forming a volcano.

Where do volcanoes come from? Hot spot- is a place where magma partially melts through Earth’s crust.

Where do volcanoes come from? Hawaii is the youngest island and is still forming over the hot spot. It contains active volcanoes and are still erupting.

Where do volcanoes come from? The island of Kauai is the oldest island. It passed over the hot spot a long time ago. It is a dormant volcano and no longer erupts

What are the kinds of volcanoes? Not all volcanoes are the same. Their different shapes depends on the kind of lava that erupts from it.

What are the kinds of volcanoes? Cinder-Cone Volcano- is shaped like a cone The magma in this kind of volcano is thick. A lot of gas is trapped in the magma. Because the magma is thick, it can become clogged in the volcano. Pressure builds up from gases in the magma. The gases finally explode out of the magma. Lava bursts into the air. It falls in pieces around the vent forming a crater. Crater- a cuplike shape forms around the vent of the volcano.

What are the kinds of volcanoes? Shield Volcano- has sides that are wide and flat. It is formed by layers of lava that build up over time. The lava flows gently out in all directions. The lava may flow from one or more openings. The volcanoes of the Hawaiian Islands are examples of shield volcanoes.

What are the kinds of volcanoes? Composite Volcano- is made up of layers of lava and ash. It forms during periods of quiet eruptions and explosive eruptions. The eruptions seem to take turns. An eruption may be explosive one time. Then the volcano may have a quiet period in which lava flows gently. Over time the layers build up to form a cone shape. This kind of volcano is usually symmetric. That means the shape on one side of the cone matches the shape on the other side.

How can you be safe around volcanoes? Scientists do not always know when a volcano will erupt. Today special equipment helps scientists predict eruptions.

How can you be safe around volcanoes? People cannot prevent eruptions. There are things that people can do stay safe where volcanoes are still active.

How can you be safe around volcanoes? Volcano Safety: Stay away from active volcanoes sites and lava flows. Have a pair of goggles and a breathing mask available for each member of your family in your emergency-supply kit. If your town has a warning system, follow all instructions. Leave the area immediately if told to do so. Wear long-sleeved shirt and long pants. If you are indoors near an erupting volcano, close all windows and doors. Make sure your pets are inside. If you are caught outdoors, find the nearest shelter and stay inside.