Dynamic Earth . Slip, Slide, & Collide The magma formed at a subduction zone rises up toward the earth's surface and builds up in magma chambers, where it feeds and creates volcanoes on the overriding plate. When this magma finds its way to the surface through a vent in the crust, the volcano erupts, expelling lava and ash. An example of this is the band of active volcanoes that encircle the Pacific Ocean, often referred to as the Ring of Fire. A subduction zone is also generated when two oceanic plates collide — the older plate is forced under the younger one — and it leads to the formation of chains of volcanic islands known as island arcs. Examples include the Mariana Islands in the western Pacific Ocean and the Aleutian Islands, off the coast of Alaska. Since the collision and subduction of plates is not a smooth process, large, powerful earthquakes are another phenomenon that result from this type of interaction. Collision Zones and Mountains What happens when two continental plates collide?
Geology Map Observations Stephanie S. Erickson Saint Paul Public Schools, Washington Technology Magnet Middle School Author Profile Students construct the Earth's tectonic plates using geologic maps. Context Audience: Required 8th grade Earth Science Class Skills and concepts that students must have mastered: Identify countries, oceans, and continents on any map. How the activity is situated in the course: Beginning activity of a unit on plate tectonics, which includes past plate movement, types of boundaries, volcanoes and earthquakes. National or State Education Standards addressed by this activity? Minnesota State Standards (8th grade Science) History and Nature of Science - Scientific World ViewThe student will understand that science is a way of knowing about the world that is characterized by empirical criteria, logical argument and skeptical review. Earth and Space Science - Earth Structure and ProcessesThe student will identify Earth's composition, structure and processes. 1. Goals Other Materials
OCE3014_Lec5_CH2 The Geological Society The Geological Society Plate Tectonics Pioneers of plate tectonicsWhat is a plate?Plate marginsPlate tectonics of the UK Pioneers of Plate Tectonics Teachers' zoneTest your knowledge Pioneers of Plate Tectonics The Geological Society The Afar region in Northern Ethiopia is the centre of a “Y” shaped rift system, where the continental lithosphere is being stretched and is splitting. The Arabian Plate is rifting away from the African plate along an active divergent ridge system, to form the Red Sea and Gulf of Aden. The rifting then extends southwards where the African Plate is itself becoming stretched along the line of the East African Rift Valley and is splitting to form two new plates; the Nubian and Somalian Plates. The point in the Afar region where the boundaries of all three plates meet is called a Triple Junction. In time, as Nubian and Somalian plates move further away from each other, the area between them will grow thinner and drop below sea level. Afar region triple junction. Image: From ‘This Dynamic Earth’ by Kious and Tilling, courtesy of the US Geological Survey
Africa's New Ocean: A Continent Splits Apart Geologist Dereje Ayalew and his colleagues from Addis Ababa University were amazed -- and frightened. They had only just stepped out of their helicopter onto the desert plains of central Ethiopia when the ground began to shake under their feet. The pilot shouted for the scientists to get back to the helicopter. And then it happened: the Earth split open. Crevices began racing toward the researchers like a zipper opening up. Normally changes to our geological environment take place almost imperceptibly. The Afar Triangle, which cuts across Ethiopia, Eritrea and Djibouti, is the largest construction site on the planet. Bubbling magma and the smell of sulphur A third crevice cuts south, splitting not far from Lake Victoria. Karte Afrika Afar-Senke english version The dramatic event that Ayalew and his colleagues witnessed in the Afar Desert on Sept. 26, 2005 was the first visual proof of this process -- and it was followed by a week-long series of earthquakes.