Fluent Essays

check attach Find an event that occurred this week that moves you. You must be able to relate it to the current chapter in some way – creativity is welcome. For instance, let’s say you read about the war in Afghanistan and parts of Pakistan. After reading the article, you check a world map and find that some remote parts of Pakistan are near the Himalayan Mountain Range. You will discover in Chapter 3 that the Himalayas were formed by a convergence of two continental plates, the Indian plate and the Eurasian plate, which causes a convergence zone that resulted in mountain uplift. And, voila!, the Himalayans are formed. Remember, geology is all about connections. The physical environment always sets the context for human events, and, often, they have a more direct influence than you may initially imagine. For example, you’re not worried about a tsunami if you live in North Dakota, but you are much more aware of the Pleistocene glaciations than you would be if you lived in Arizona. You may use an article from the following sources: Reuters National Public Radio Another news outlet if you include a paragraph telling me why you chose it. Turn in: A document that includes the entire story (copy and pasted from the original site). The citation (where you got it and when). The link. A map of the location of the event that was not included in the article. Paragraph of what you think about the news (good, bad, indifferent – just tell me why). Paragraph explaining at least one geologic connection that relates to this week’s chapter. Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Volcanic Eruptions  Unpredictable, dangerous.  Build large mountains.  Blow mountains to bits.  Eruptions can…  Provide highly productive soils to feed a civilization.  Can extinguish a civilization in a matter of minutes.  Eruptions effect climate. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Volcanic Materials  The products of volcanic eruption take three forms:  Lava flows – Molten rock that moves over the ground.  Pyroclastic debris – Fragments blown out of a volcano.  Volcanic gases – Vapor and aerosols that exit a volcano. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Lava Flows  Lava can be thin and runny or thick and sticky.  Flow style depends on viscosity, which depends upon...  Composition, especially silica (SiO2), Fe, and Mg content.  Temperature.  Gas content.  Crystal content. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Lava Compositions  Lavas with high silica / low Fe and Mg are called...  Silicic, felsic, or rhyolitic.  Lavas with low silica / high Fe and Mg are called…  Mafic or basaltic.  Lavas with moderate silica, Fe, and Mg are called…  Intermediate or andesitic. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Basaltic Lava Flows  Mafic lava – Very hot, low silica and low viscosity.  Basalt flows are often thin and fluid.  They can flow rapidly (up to 100 km/hr).  They can flow for long distances (up to several 100 km). Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Basaltic Lava Flows  Pahoehoe (pa-hoy-hoy) - a Hawaiian word describing basalt with a glassy, ropy texture.  Pahoehoe forms when extremely hot basalt forms a skin.  With flow, the skin is rolled into ropy ridges and furrows. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Basaltic Lava Flows  A’a’ (ah-ah) is a Hawaiian word describing basalt that solidifies with a jagged, sharp, angular texture.  A’a’ forms when hot flowing basalt cools and thickens.  With flow, lava crumbles into shards and fragments. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Basaltic Lava Flows  A cooled crust forms on top of a basalt flow.  A conduit – a lava tube – develops in the flow.  Tubes prevent cooling, facilitating flow for miles.  Lava tubes become caves that can later transmit water. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Basaltic Lava Flows  Underwater, basalt cools instantly; it cannot flow.  It cools to form a rounded blob called a pillow.  The pillow surface is cracked, quenched glass.  Lava pressure ruptures a pillow to form the next blob.  The process repeats to form a mound of pillow basalts.  Common on the mid-ocean ridge. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Andesitic Lava Flows  Higher SiO2 makes andesitic lavas viscous.  Unlike basalt, they do not flow rapidly.  Instead, they mound around the vent and flow slowly.  The outer crust fractures, creating rubble.  Andesitic lava flows remain close to the vent. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Rhyolitic Lava Flows  Rhyolite, with the highest SiO2, is the most viscous lava.  Rhyolitic lava rarely flows.  Rather, lava plugs the vent as a lava dome.  Sometimes, lava domes are blown to smithereens. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Basaltic Pyroclastic Debris  Glass shards and fragmented lava in a range of sizes.  Basaltic eruptions generate a lot of spatter.  Lapilli – Pea to plum-sized material.  Blocks and bombs – Apple to refrigerator-sized. Pele’s Hair – Strands of glass created by flying lava droplets. Bombs – Streamlined fragments of ejected lava. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Explosive Pyroclastic Debris  Intermediate and felsic magmas erupt explosively.  More viscous than basaltic magma (from SiO2).  Contain more gas.  Produce large quantities of volcanic ash. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Pyroclastic Flows  Pyroclastic flows (or, nuee ardentes - French):A  Avalanches of hot ash (200Co–450oC) that race downslope.  Moving up to 300 kph, they Incinerate all in their path.  Immediately deadly; they kill everything quickly.  Many famous examples: Mt. Vesuvius, Mt. Pelee, and Mt. Augustine. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Pyroclastic Deposits  Tephra – Deposits of pyroclastic debris of any size.  Tuff – Lithified ash with or without lapilli.  Air-fall tuff – Accumulations of ash that fell like snow.  Ignimbrite (welded tuff) – Tuff that is deposited while hot. Hot pyroclastic flow material. Fuses together while cooling. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Volcaniclastic Deposits  Blocks – Preexisting rock fragmented by eruption.  Blown out of a volcanic vent, blocks pile up nearby.  Create unstable slopes that easily fail. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Lahars  Tephra is readily moved by water as a debris flow.  Known as lahars, these flows are often deadly.  Lahars move rapidly (up to 50 km per hour).  They have the consistency of wet cement,.  A distinct hazard to people living in volcanic valleys. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Volcanic Gas  Up to 9\% of magma may be gas.  Water (H2O) – Most abundant gas.  Carbon dioxide (CO2) – Second in abundance.  Sulfur dioxide (SO2) – Rotten egg smell.  Magma composition controls gas content.  Felsic magmas are gas-rich; mafic magmas are less so. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Volcanic Gas  Gases are expelled as magma rises.  SO2 reacts with water to form aerosol sulfuric acid.  Style of gas escape controls eruption violence.  Low viscosity (basalt) – Easy escape; mellow eruption.  High viscosity (rhyolite) – Difficult escape; violent eruption.  Gas bubbles in rock are called vesicles. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Predicting Eruptions  Warning signs precede most eruptions.  Earthquake activity – Magma flow increases seismicity.  Heat flow – Magma causes volcanoes to “heat up.”  Changes in shape – Magma causes volcanoes to inflate.  Emission increases – Changes in gas mix and volume.  These signs indicate that an eruption is imminent.  They cannot predict eruption timing or style. Edited by Joao Santos Essentials of Geology, 3rd edition, by Stephen MarshakEssentials of Geology, 3rd edition, by Stephen Marshak Chapter 5: The Wrath of Vulcan: Volcanic EruptionsChapter 5: The Wrath of Vulcan: Volcanic Eruptions Volcanoes and Climate  Volcanic eruptions can be large enough to alter climate.  Ash and aerosols high in the atmosphere block sunlight.  This causes atmospheric cooling. 1815 was the “year without a summer” due to Tambora. Edited by Joao Santos