Transcript Slide 1
(Mon) Scientists use 2 pieces of evidence to support the theory of plate tectonics – specifically that sea floor spreading was happening. What is this evidence and explain how it works. (5 pts / 5 min) (Mon) Scientists use 2 pieces of evidence to support the theory of plate tectonics – specifically that sea floor spreading was happening. List and Explain evidence? 1. The age of the rocks around a mid-ocean ridge As you get farther from the center of the ridge, the rocks get older The rock ages are the same on both sides of the ridge (mirror) 2. Paleomagnetism of the rocks on the sea floor The rock magnetic pattern changes as you get farther from the center giving a “zebra pattern” The patterns are the same on both sides of the ridge (mirror) (Tue) Magma rises to push apart plates at divergent boundaries. If magma is just really hot rocks, why does magma rise? (5 min / 3 pts) (Tue) Magma rises to push apart plates at divergent boundaries. If magma is just really hot rocks, why does magma rise? Really hot magma is less dense than the other magma around it If something has a lower density, it floats So the hot magma rises because it floats up through the cooler magma around it (Wed) An ocean-continent and ocean-ocean convergent plate boundary usually makes a line of volcanoes along the edge. Why do these types of convergent boundary make volcanoes while a continent-continent boundary does not? (5 min / 5 pts) (Wed) An ocean-continent and ocean-ocean convergent plate boundary usually makes a line of volcanoes along the edge. Why do these types of convergent boundary make volcanoes while a continent-continent boundary does not? (5 min / 5 pts) Ocean-Ocean and Ocean-Continent boundaries both have oceanic crust as one of the plates Oceanic crust is soaked with water The water is subducted with the crust at the boundary The water is heated and turns to steam by the asthenosphere The steam brings up magma to make volcanoes. (Thu) A geologist is studying a tectonic plate boundary found along the edge of a continent. A coastal mountain range has formed on the continent near the boundary and some of the mountains are active volcanoes. What type of boundary is this and why do you say so? (5 min / 5 pts) (Thu) A geologist is studying a tectonic plate boundary found along the edge of a continent. A coastal mountain range has formed on the continent near the boundary and some of the mountains are active volcanoes. What type of boundary is this and why do you say so? What type: Convergent Plate Boundary Ocean – Continent Boundary Why: Ocean plate subducted under continental plate Steam causes volcanic activity along continental margin (Fri) Final review for the quiz…… Use this time to get ready for the quiz!