Chapter 8 Volcanoes

Science Entry 2 Objectives chapter 8 I will know the difference between non explosive and explosive volcanic eruptions. I will explain how the composition of magma determines they type of volcanic eruption tat will occur. I will know what the main types of lava and volcanic debris there is.

Entry 2 Science Vocabulary Remember if you want an extra point you can create a word wall. Please see me afterschool or which word you would like. You can only do one word. Magma Vent Lava Volcano Pyroclastic material

Entry 3 Nonexplosive Eruptions Lava flows come from non explosive eruptions. Relatively calm outpourings of lava Huge outpouring of molten rock Mountains can form over hundreds of thousands of years.

Entry 4 Science vocabulary homework

Entry 5 Explosive Eruptions Clouds of hot debris and gases shoot out Sometimes at supersonic speed. Molten rock blown into a million of pieces that harden in the air. Blast millions of tons of solid rock from a volcano. In minutes an explosive eruption can demolish rock formations that took thousands of years to form. A volcano may shrink in size after repeated explosive eruptions.

Entry 6 Magma Magma- hot, liquid material that creates volcanoes Magma collects in magma chambers. Magma rises through the holes in the Earths crust called vents. Magma that erupts and flows on the Earth’s surface is called lava. Magma that erupts as fragments of molten material that solidly in the air is called pyroclastic material.

Entry 7 Water Magma Water- a volcano can have higher chances of erupting explosively if magma has a high water content. Like a can of soda, when you shake the can up. The more water magma contains the more pressure it creates.

Entry 8 Silica Magma A high quantity of silica (mineral) found in magma can cause major explosions. Silica rich magma has a thick, stiff consistency. It flows slowly and tends to harden in the volcano's vent. This plugs the vent, producing pressure. Lower amounts of silica results in calmer eruptions.

Entry 9: What erupts from a volcano? Depending on how explosive a volcanic eruption is, magma erupts as either lava or pyroclastic material. Non explosive eruptions produce mostly lava Explosive eruptions produce mostly pyroclastic material. Over years a volcano can have explosive and non explosive eruptions. In a single eruption a volcano may have both non explosive and explosive eruptions.

Entry ___ What is Lava? Lava is magma that flows onto the Earth’s surface. Once magma erupts and flows onto earth’s surface it is lava. Lava can be thick or thin.

Entry ____ Types of Lava Blocky Lava Blocky Lava - is cool, stiff lava that cannot travel far from the erupting vent. Blocky lava oozes from a volcano ONLY after an explosive eruption has released much of the gas pressure from the magma chamber. After it cools, blocky lava forms jumbled heaps of sharp-edged chunks.

Entry ___ Aa lava “Aa” lava is a Hawaiian word that refers to a type of lava that has a jagged surface. The stiff lava pours out quickly and forms a brittle crust. Crust is torn into jagged pieces as the molten lava under it continues to flow.

Entry ___ Pillow Lava Forms when lava erupts underwater. Forms rounded lumps that are the size and shape of pillows. Pillows lava has a rounded shape because contact with water causes fast cooling.

Entry ___ Your turn! Sketch in this entry the three types of lava. Label them and draw them into this entry. I will be checking it this week.

Pyroclastic Material Entry 15 Rock fragments created by explosive volcanic eruptions. Produced when magma explodes form a volcano and solidifies in the air. Also produced when existing rock is shattered by powerful eruptions. A variety of sizes, from boulders the size of houses to particles so small in atmosphere.

Entry 16 Pyroclastic Material Types Volcanic blocks – the largest piece of pyroclastic material. Consist of solid rock blasted out of volcanoes. Volcanic bombs- large blobs of magma that harden in the air. Lapilli- “little stones” in Italian. Pebble like bits of pyroclastic material. Volcanic Ash- particles that are less than 2 m in diameter.

Entry 17 Chap. 8. Section 2 Volcanic Effects on Earth Objectives I will describe the effects that volcanoes have on Earth. I will compare the different types of volcanoes

Entry 18 Vocabulary 1. Shield Volcano 2. cinder cone volcano 3. composite volcano 4. crater 5. caldera

Effects on Earth Entry 19 Explosive Impact Effects - Because it is thrown high in the air, ash ejected during explosive volcanic eruptions can block out the sun for days. Ash can blow down trees and buildings. Cover towns in blankets of ash. Flows- Clouds of hot ash can flow rapidly downhill like an avalanche, choking and searing all living things. Mudflows can create rivers of ash

Entry 20 Fallout Effects on Earth As volcanic ash falls to the ground, the effects can be devastating. Buildings may collapse under the weight of so mush ash. Ash can dam up river valleys, resulting in massive floods. Too much ash can smother crops, causing food shortages and loss of livestock.

Entry 21 Climatic Fluctuation In large eruptions, volcanic ash, along with sulfur rich gases, can reach the upper atmosphere. As the ash and gases spread around the globe they can block out enough sunlight to cause the average global surface temperature. To drop. This temperature drop can last for years, bringing wetter, milder summers and longer, harsher winters. This can cause food shortages that result in starvation and disease.

Entry 22 Shield Volcanoes Shield Volcano – build out of layers of lave from repeated non explosive eruptions. Because the lava is very runny, it spreads out over a wide area. Over time the layers of lava create a volcano with gently sloping sides. Although their sides are not very steep, shield volcanoes can be enormous..

Entry 23 Cinder Cone Volcanoes Small volcanic cones made entirely of pyroclastic material from moderate explosive eruption. The pyroclastic material forms steeper slopes with a narrower base than the lava flows of shield volcanoes. Usually erupt for only a short time and often occur in clusters. They erode quickly.

Entry 24 Composite volcanoes Also known as stratovolcanoes, most common types of volcanoes. They are formed by explosive eruptions of pyroclastic material followed by quieter outpourings of lava. This creates alternating layers of pyroclastic material and lava. They have broad bases and sides that get steeper toward the summit.

Entry 25 Craters and Calderas Crater- top of the central vent in most volcanoes is a funnel shaped pit A crater’s funnel shape results form explosions of material out of the vent as well as the collapse of material from the crater’s rim back into the vent. Caldera- forms when a magma chamber that supplies material to a volcano empties and it’s roof collapses. Causing the ground to sink, leaving a large, circular depression.

Entry 26 Lava Plateaus Most of the lava on Earth’s continents erupts for long cracks, or fissures, in the crust. When it runs for a long period of time the landform is known as lava plateau