* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download The Earth`s Interior & Plate Tectonics
Survey
Document related concepts
Geochemistry wikipedia , lookup
Schiehallion experiment wikipedia , lookup
Post-glacial rebound wikipedia , lookup
Age of the Earth wikipedia , lookup
History of geomagnetism wikipedia , lookup
Tectonic–climatic interaction wikipedia , lookup
History of Earth wikipedia , lookup
History of geology wikipedia , lookup
Oceanic trench wikipedia , lookup
Mantle plume wikipedia , lookup
Transcript
The Earth’s Interior & Plate Tectonics Physical Science Chapter 17 Section 1 The Earth’s Interior The Earth’s Interior can be broken up into 4 major zones Crust Mantle Outer core Inner core Surrounding the interior is the Atmosphere The Crust The crust is very thin (average 20 km) & Brokenup into plates. This does not sound very thin but if you were to imagine the Earth as a football, the crust would be about ½millimeter thick. The thinnest parts are under the oceans (Oceanic Crust) and go to a depth of roughly 10 kilometers. It is more dense than under continents. The thickest parts are the continents (Continental Crust) which extend down to 35 kilometers on average. The continental crust in the Himalayas is some 75 kilometres deep. The Mantle A rocky layer located below the crust with a thickness of 2885 kilometers The upper part of the mantle together with the crust is called the Lithosphere. The Mantle (cont…) The mantle extends about half way to the center. It's made of solid rock and behaves like an viscous liquid. The convection of heat from the center of the Earth is what ultimately drives the movement of the tectonic plates and cause mountains to rise. The Outer Core A layer about 2270 kilometers thick, which is made of liquid iron & nickel. The movement of this liquid core is responsible for the Earth's magnetic field The Inner Core The bit in the middle! It is made of solid iron and nickel with a radius of about 1216 km. Temperatures in the core are thought to be in the region of 5000-6000°c and it's solid due to the massive pressure. The Theory of Plate Tectonics States that Earth's rigid outer shell, called the lithosphere, consists of seven large and numerous smaller segments called plates that are in motion relative to each other. Origins Alfred Wegner proposed Continental Drift when he noticed that the continents fit together like jigsaw pieces. Later, with more evidence, this became the theory of Plate Tectonics Evidence for Plate Tectonics The evidence Wegner used for his original theory Continents fit together Matching Rocks & Fossils Paleomagnetism: Study of the changes in Earth’s Magnetic Field Evidence for the theory (cont…) The edges of these plates (called Plate Boundaries), where they move against each other, are sites of intense geologic activity, such as earthquakes, volcanoes, and mountain building. Types of Plate Boundaries A. Divergent plate boundaries B. Convergent plate boundaries C. Transform fault boundaries Divergent Plate Boundaries (constructive margins) Two plates move apart Mantle material upwells to create new seafloor Continental rifts form at spreading centers within a continent Divergent Plate Boundaries (cont…) Convergent plate boundaries (destructive margins) Plates collide, an ocean trench forms and lithosphere is subducted into the mantle There are three types of Convergent Plate Boundary Oceanic-continental convergence Denser oceanic slab sinks into the asthenosphere Pockets of magma develop and rise Continental volcanic arcs form e.g., Andes Mountain Range e.g., Cascades Mountain Range Oceanic-oceanic convergence Two oceanic slabs converge and one descends beneath the other Often forms volcanoes on the ocean floor Volcanic island arcs forms as volcanoes emerge from the sea e.g., Aleutian islands e.g., Mariana islands Continental-continental convergence When subducting plates contain continental material, two continents collide Can produce new mountain ranges such as the Himalayas Example of a continental-continental Subduction Transform Fault boundaries Plates slide past one another No new crust is created No crust is destroyed