WHERE PLATES MEET <ul><li>LEARNING OBJECTIVES: </li></ul><ul><li>Most students should be able to: </li></ul><ul><li>Understand the process by which fold mountains arise; </li></ul><ul><li>Appreciate the dangers of living in volcanic and earthquake prone areas, like fold mountains; </li></ul><ul><li>Know that mountains in Britain were once areas of volcanic activity </li></ul>Enquiry Question: Where are mountain environments found? What challenges do mountain environments pose?
A destructive plate boundary is found where a continental plate meets an oceanic plate. The oceanic plate descends under the continental plate because it is denser. As the plate descends it starts to melt due to the friction caused by the movement between the plates. This melted plate is now hot, liquid rock (magma). The magma rises through the gaps in the continental plate. If it reaches the surface, the liquid rock forms a volcano. Destructive plate boundary
THE DOMINO EFFECT: WHAT HAPPENS AT A DESTRUCTIVE PLATE BOUNDARY?
In a subduction zone, the oceanic crust melts as it pushes down into the mantle, forming a deep ocean trench. The continental crust is crumpled into fold mountains. The heavier oceanic crust pushes beneath the lighter continental crust . The Nazca Plate (oceanic crust) is being pushed towards the South American Plate (continental crust). This process is called subduction Because crust is lost, or destroyed, in this process it is known as a destructive boundary . Earthquakes and volcanoes occur here THE DOMINO EFFECT: WHAT HAPPENS AT A DESTRUCTIVE PLATE BOUNDARY?
The November 13, 1985 lahar from Nevado del Ruiz, Colombia -- After travelling over 70 kilometers from the summit of the Nevado del Ruiz volcano, this destructive lahar buried the village of Armero at the mouth of the River Lagunillas canyon, which was located in the center of this photograph. The lahar killed over 23,000 people, most of which were from Armero. Courtesy of J. Marso, USGS.