Plate Tectonics

A+ MATERIALS ON Plate Tectonics THEORY The theory that earths crust and upper mantle are broken into sections is called.... Plate Tectonics Plates are composed of the.... Crust and part of the upper mantle The lithosphere is composed of the..... Crust and upper mantle Plates float on the... Asthenosphere Plates can- A-pull apart, collide, and move past one another B-erupt and form precipitation A- pull apart, collide and move past one another The boundary between two plates that are moving apart is a...........boundary ... Alfred Wegener had four different pieces of evidence for his theory of continental drift. What were his four pieces of evidence? 1. Puzzle like fit 2. Fossil evidence -Some fossil species found on different continents -Match up when lineup continents -water separating; animals cannot swim or fly across water 3. Rock evidence -similar rock structures and ages create regions throughout matching continents 4. Glacial Evidence -glacial deposits/grooves in various continents align together ***Keep in mind, glaciers can't travel across water Convection Happens in the lower asthenosphere where it is hotter; it becomes less dense and rises. It then hit the little sphere, spreads out, and cool. It then starts to sink because it is more dense. As it syncs the temperature rises, and it melts again, creating a cycle. The theory of plate tectonics Is the theory that the earths lithosphere is divided into tectonic plates that move around on top of the asthenosphere Layers of the earth: *Lithosphere -the outer most, rigid layer of the earth -composed of the crust and the rigid upper part of the mantle -divided into pieces called tectonic plates *Asthenosphere -plastic like layer of the mantle on which pieces of the lithosphere move. Evidence for plate tectonics Evidence 1: earthquakes and volcanic activity around plate boundaries Evidence 2: convection occurs as a result of change in density Evidence 3: hotspots-volcanic activity far from plate boundaries Evidence 4: -Seafloor spreading- occurs at mid ocean ridges (underwater mountains) -as plates move away from one another, the seafloor spreads apart and magma fills the gaps -as knew crust forms, older crust gets pushed outward -youngest rock is found near the ridge -oldest continental rocks are about 4 billion years old -oldest oceanic rocks are about 180 million years old Hotspots Hotspots are where volcanoes are created: the magma chamber doesn't move, but the tectonic plate above it does. This makes a chain of volcanos. The further away the volcano is from the hotspot, the older the rock is. What is the primary force that drives the movement of tectonic plates? Mantle convection currents What type of plate boundary is associated with the formation of mid-ocean ridges? Divergent boundary Which layer of the Earth is broken into tectonic plates? Lithosphere What happens when an oceanic plate collides with a continental plate? The denser oceanic plate subducts beneath the continental plate What geological feature forms when two continental plates collide? Mountain ranges Which type of plate boundary is responsible for creating deep-sea trenches? Convergent boundary What process occurs at a transform boundary? Plates slide past each other What is the term for the process where new oceanic crust is formed at a mid-ocean ridge? Seafloor spreading Which type of boundary is most associated with earthquakes but not volcanoes? Transform boundary What is the name of the supercontinent that existed about 300 million years ago? Pangaea Which scientist is credited with developing the theory of continental drift? Alfred Wegener What happens to the age of oceanic crust as you move away from a mid-ocean ridge? It gets older What type of boundary is found along the San Andreas Fault in California? Transform boundary