| A | B |
|---|
| Cinder cone volcanic eruptions are | explosive and throw lava high into the air |
| Composite volcanoes are found mostly where ___________. | Earth's plates come together and one plate sinks beneath the other |
| Granitic magma eruptions are | slow |
| Of the three types of volcanoes, which is the least explosive? | shield volcanoes |
| What two factors control the explosiveness of an eruption? | the amount of water vapor and silica in the magma |
| High levels of silica causes magma to become __________. | thicker |
| The difference between basaltic and granitic magma is __________. | the amount of silica |
| Shield volcanoes are the result of __________. | basaltic lava flows |
| Intrusive igneous rocks are those which __________. | cool beneath Earth's surface |
| What are batholiths? | magma bodies that cool slowly before they reach Earth's surface |
| What is the difference between a dike and a sill? | Dikes are formed across vertical cracks, and sills are formed across horizontal ones. |
| Calderas form __________. | after an eruption |
| Intrusive igneous rock bodies such as batholiths and sills form when __________. | magma solidifies underground |
| A volcanic neck is the remains of a(n) ___________. | eroded volcano |
| A volcano is an opening in Earth that erupts__________. | A) gases |
| A pyroclastic flow is__________. | hot volcanic ash and debris that rushes down the side of a volcano |
| Sulfurous gases emitted by volcanoes __________. | can mix with water vapor and form acid rain |
| What causes magma to rise to the surface? | Magma is less dense than rock. |
| What is the difference between lava and magma? | After magma reaches the surface it's called lava. |
| What is a vent? | the opening in a volcano |
| Magma originates in which layer of Earth? | mantle |
| Volcanoes often are found in areas on Earth where __________. | plates collide |
| Islands like Iceland are often formed due to __________. | B) plate movement |
| Convergent plate boundaries __________. | force one plate beneath Earth's surface |
| The Hawaiian Islands are formed because of __________. | hot spots |
| What type of volcanoes are the Hawaiian islands? | Shield- The volcanoes of the Hawaiian Islands produce baslatic lava that spread out in flat layers. The buildup on these layesr forms a broad volcano with gently sloping side which is characteristic of a shield volcano. |
| Magma that is forced into a crack that cuts across rock layers and hardens into igneous rock is called a(n) | Dike- Magma sometimes squeezes into cracks in rock below the surface. Magma that is forced into a crack that cuts across rock layers and hardens is called a dike. |
| Which of the following is a steep-sided mountain of loosely packed tephra? | Cinder cone- Explosive eruptions throw lava and rock into the air. When the rock or soldified lava falls to the ground, it forms a steep-sided volcano known as a cinder-cone volcano. |
| Why does Iceland have volcanic activity? | Iceland has volcanic activity because it is part of the Mid-Altanic Ridge, a divergent plate boundary (area area where Earth's plates are moving apart). |
| Which of the following forms when magma bodies forced upward from inside Earth solidify before reaching the surface? | Batholiths form when magma bodies that are being forced upward from inside Earth cool slowly and solidify before reachng the surface. |
| Which of the following is the coarsest type of tephra? | Volcanic blocks- Tepha varies in size from volcanic ash (the smallest particles), to cinders, to larger rocks called bombs and blocks. |
| Where do volcanoes occur in the United States? | the west coast |
| Which type of magma often forms at a convergent plate boundary? | Andesitic magma is more silica rich than basaltic magma, but less silica rich than granitic magma. It often forms at convergent plate boundaries where one plate slides under another. |
