Igneous+Processes

Define an igneous rock. can either form underground or above ground. underground- when the magma is trapped in small pockets inside the earth. above ground- also formed when lava cools above ground. -chrissy Rocks formed by the cooling and solidifying of molten materials. Igneous rocks can form beneath the Earth's surface, or at its surface, as lava. ~Lisha~ What is the difference between magma and lava? magma is found underground. when magma reaches the surface it then becomes lava. -chrissy What is the relationship between crystal size and cooling rate? larger crystals cool slower and smaller crystals cool faster. -chrissy Some igneous rocks don’t have crystals. They are called ___. Which 3 rocks are they?
 * Honors Earth Science Igneous Processes Review**

They are called glasses. the three kinds are pumice, obsidian, and scoria. -chrissy Compare plutonic vs. volcanic rocks (where are they formed?) Volcanic is extrusive and is fine-grained with a glassy texture, formed on the earths surface, while plutonic is an igneous intrusion. Plutonic is formed by slow cooling of a body of melted rock, usually deep under the earths surface. -Shelby Compare intrusive vs. extrusive textures. extrusive crystals are on the outside of the rock while intrusive crystals are on the inside of the rock. -chrissy Compare felsic vs. mafic rocks (chemistry and color). felsic-light colored, mostly made of feldspar and quartz mafic- dark colored, made of iron materials mostly -chrissy How are volcanoes related to plate boundaries (2 ways)? Volcanoes are usually formed by divergent plate boundaries, when two plates move farther and farther way from each other, which form a ridge, that however causes lava to flow to the surface from the mantle and makes it easy for a volcano to be formed. But, when convergent plate boundaries form volcanoes, its because the two plates push together, and one plate is heavier than the other, so it goes on top of the other, that the makes magma push to the surface to form volcanoes, which usually happen to be mountain ranges. However, when a volcano is formed away from a plate, like in the center is placed there because of a mantle plume, which is when the lava pushes to the crust, gets extremely hot and forces its way through to the surface. -Shelby Define and explain a hot spot. a location on the Earth's surface that has experienced active volcanism for a long period of time -chrissy A place deep within the Earth where hot magma rises to just underneath the surface, creating a bulge and volcanic activity~Lisha~ What and where are two hot spots in the U.S.? hawaii and yellowstone. -chrissy Contrast deep source vs. shallow source eruptions with regards to explosiveness, lava chemistry, temperature and viscosity. For each of the 4 types of volcanoes: give a geographic example, describe the physical shape and size of the volcano, its lava, its eruption behavior and any pyroclastics products it makes. Fissure eruptions: Flat, wide armed, on the surface eruption. Generated along a linear fracture. Malfic lava, which is very hot. The volcano is deep within the surface. Can be located anywhere. But, have a low degree of eruption. that's true but it has a felsic lava chemistry. ~Lisha~ Stratovolcanoes: Known as a Composite Cone. Medium in size, and is steep. This volcano has many layers. The lava from this volcano tend to cool and harden before it goes very far. This volcano can produce both felsic and malfic lava, however its lava temperature is cooler, and can only be found on continents. The composite cone volcano has a very alternating eruption behavior. that's true and also the source depth is shallow and it's degree of explosiveness is high alternating. ~Lisha~ Shield: Largest volcano, very hot and deep. This volcano can only be found in the ocean, and has low eruption behavior. and its lava chemistry is mafic. ~Lisha~ Cinder cones: Malfic lava is produced, but its less hot. The volcano can be on both land and oceans, and has small bursts of explosives. - shelby it's the smallest and its source depth is shallow and it's parasitic- in other words it grows on another volcano. ~Lisha~ What type of volcanism occurred in Michigan ? What happened to cause it? Where did it happen? ^^Fissure eruptions. The ground split apart (plates). Keweenaw Peninsula. Flood Basalts- Flows of basaltic lava that fissure from numerous cracks or fissures and commonly cover extensive areas to hundreds of miles. - Elizabeth What are flood basalts? result in a giant volcanic eruption or several eruptions. which end up leaving large areas left with basalt lava. - Shelby  What does the texture of a porphyry indicate about its rate of cooling? The texture of a porphyritic rock indicates that it went through two stages of cooling. -Laura What creates a vesicular texture? What 3 rocks might have it? The vesicular texture of bubble-holes in a rock is caused by gas venting during formation -Laura What are a few ways to identify a tuff? Tuff is a rock that consists of volcanic material thats ejected, and has fallen to earth, which then forms into a rock. The rocks usually composed of welded volcanic ash, with large particles, much like cinders and rock fragments. -Shelby Compare and contrast aa and pahoehoe. Aa's texture is very sharp and jagged while pahoehoe has a more smooth, ropy texture. -Laura For each of these sizes, give an example of a common object that is the same size: Bomb = It is about the size of a fist. Lapilli = It is about the size of gravel. Ash = Ash is about the same size as sand. Ash is a powdery residue ~Lisha~

Cinders = Cinders are usually the same size as gravel. -Laura How would you recognize obsidian? What type of chemistry does it have? Obsidian is very hard, looks very much like glass. It breaks into sharp edges, that can easily cut through many materials. You can find obsidian in any color, however obsidian is mostly black or brown, Its a solid rock, thats composed of silicon dioxide. - Shelby What are the main gases given off during volcanic eruptions? 1. Water vapor 2. Carbon Dioxide 3. Sulfur Dioxide -Laura What is a pyroclastic flow? How is it different from an ash fall? A pyroclastic flow is, hot, fast moving flow of volcanic ash, rocks, dust, and debris that move down the slope of a volcano during an eruption, and is a very dense material. An ash fall is a deposit formed by different layers piled ontop of each other. but, forms mainly from volcanic ash that has fallen through the air which came from an eruption cloud. - Shelby

What are the top 3 dangers that can kill people during eruptions? poisenous gasses, mudslides, pyroclastic flows. -chrissy How does a caldera form? Where are some calderas in the United States ? It forms in essentially 3 basic steps.

1) Magma comes to the surface and creates a magma chamber. The volcano forms the way they do (successive eruptions)

2) After many millions of years the magma and pressure subsides in the magma chamber. This means there is less pressure under the volcano and the volcanoe starts to collapse

3) The sides of the volcano collapse and may/may not become filled with water.

A caldera can be found in Yellowstone National Park and also in New Mexico.

-Julian-