PPTMODULE6-S11-ESci (Earth Science) PDF

EARTH SCIENCE 6 “MOUNTAINS AND VOLCANISM” Ms. Ruffa Mae Simara,LPT  6 Earth Science MOUNTAINS AND VOLCANISM 1. To identify the geologic forces that shape the earth 2. Recognize the type of mountains and volcanoes 3. Define mounta...

EARTH SCIENCE 6 “MOUNTAINS AND VOLCANISM” Ms. Ruffa Mae Simara,LPT  6 Earth Science MOUNTAINS AND VOLCANISM 1. To identify the geologic forces that shape the earth 2. Recognize the type of mountains and volcanoes 3. Define mountains and volcanoes and their relation to one another  6 Earth Science TOURIST DESTINATIONS  6 Earth Science MOUNTAINS Landform that rises prominently above its surroundings, generally exhibiting steep slopes, a relatively confined summit area, and considerable local relief. Mountains generally are understood to be larger than hills, but the term has no standardized geological meaning. 2 VOLCANISM: Its  6 Earth Science OROGENESIS VOLCANISM: Its  6 Earth Science OROGENESIS VOLCANISM: Its  6 Earth Science VOLCANISM: Its  6 Earth Science Types of Mountains 1.Volcanic Mountains 2.Fold Mountains 3.Block Mountains 4.Residual Mountains 5.Dome Mountains 2 VOLCANISM: Its  6 Earth Science Types of Mountains 1.Volcanic Mountains: When tectonic plates move about, volcanoes are formed, and when volcanoes erupt, mountains are formed in turn.A shield volcano has a gently sloping cone due to the low viscosity of the emitted material, primarily basalt. Most volcanic mountains occur in a band surrounding the Pacific Ocean. Collectively they are known as the Pacific Ring of Fire. The famous volcanic mountains are stratovolcanoes or shield volcanoes. 2  6 Earth Science Types of Mountains 2. Fold mountains are created where two or more of Earth’s tectonic plates are pushed together. At these colliding, compressing boundaries, rocks and debris are warped and folded into rocky outcrops, hills, mountains, and entire mountain ranges. 3. Block Mountains: The raising of a fault block leads to the formation of block mountains. Higher blocks are called horsts and troughs are known as grabens. When the surface is spread apart, it leads tensional forces coming into place when these tension forces split apart; it causes the centre block to drop down. An example of this is the Sierra Nevada Range in the United States. 2  6 Earth Science Types of Mountains 4. Residual mountains are the remnants of previously existing mountains that have been subjected to weathering and erosion for an extended period. The residual mountains owe their current shape to erosion by rivers, glaciers, wind, etc. 5. Dome mountains are formed when large globs of magma float up from beneath the crust and push up surface rocks, creating a rounded swelling in the crust. Once the magma cools, it creates a large dome of harder rock under the surface, which erosion sometimes reveals. 2  6 Earth Science 2 VOLCANISM: Its  6 Earth Science VOLCANISM Volcanism is the eruption of molten rock (magma) onto the surface of a planet. A volcano is the vent through which magma and gases are discharged. Magma that reaches the surface is called lava. Volcanos are named for Vulcan the Roman god of fire! VOLCANISM: Its  6 Earth Science Do you know that? A volcano is a vent or opening on planet’s surface which allows molten rock called magma, volcanic ash and gas to escape out onto its surface. The hot magma erupting from a volcano is called lava.  6 Earth Science Types of Volcanoes  6 Earth Science Types of Volcanoes Composite volcanoes are steep-sided volcanoes composed of many layers of volcanic rocks, usually made from high-viscosity lava, ash and rock debris. These types of volcanoes are tall conical mountains composed of lava flows and other ejecta in alternate layers, the strata that give rise to the name.  6 Earth Science Types of Volcanoes Shield volcanoes are volcanoes shaped like a bowl or shield in the middle with long gentle slopes made by basaltic lava flows. These are formed by the eruption of low-viscosity lava that can flow a great distance from a vent. They generally do not explode catastrophically. Since low-viscosity magma is typically low in silica, shield volcanoes are more common in oceanic than continental settings.  6 Earth Science Types of Volcanoes Cinder cones are circular or oval cones made up of small fragments of lava from a single vent that have been blown up. Cinder cones result from eruptions of mostly small pieces of scoria and pyroclastics that build up around the vent. Most cinder cones erupt only once. Cinder cones may form as flank vents on larger volcanoes, or occur on their own.  6 Earth Science Types of Volcanoes Lava domes are formed when erupting lava is too thick to flow and makes a steep-sided mound as the lava piles up near the volcanic vent. They are built by slow eruptions of highly viscous lava. They are sometimes formed within the crater of a previous volcanic eruption. Like a composite volcano, they can produce violent, explosive eruptions, but their lava generally does not flow far from the originating vent.  6 Earth Science Types of Volcanic Eruption  6 Earth Science Types of Volcanic Eruption  6 Earth Science Three Definition of Volcanoes  6 Earth Science What determines Products of Eruption the degree of violence associated with volcanic activity? Magma – molten rock or liquid that is mostly silica Lava – solidified magma Pyroclasts – from the Greek pyro, “fire”, and clast “broken” – rock fragments (pyroclastic debris is also called tephra) Lava flow s – fissures in the ground Extrusive rock - surface rock resulting from volcanic activity (rock formed by solidification of lava)  6 Earth Science Products of Eruption Crater – funnel shaped pit at CRAT the top of a volcano. formed ER when material is blown out of the volcano by explosions Caldera – when the volcano collapses due to an empty magma chamber  6 Earth Science The Pacific Ring of Fire -It is a string of volcanoes and sites of seismic activity around the edges of the Pacific Ocean. -It isn’t quite a circular ring. It is shaped more like a 40,000- kilometer (25,000- mile) horseshoe. -A string of 452 volcanoes.  6 Earth Science VOLCANISM: Its