plate tectonics through earth history
plate tectonics theory
First, lets review plate tectonics theory. Plate tectonics theory explains why: Earths geography has changed over time and continues to change today. some places are prone to earthquakes while others are not. certain regions may have deadly, mild, or no volcanic eruptions. mountain ranges are located where they are. many ore deposits are located where they are. living and fossil species are found where they are. Plate tectonic motions affect Earths rock cycle, climate, and the evolution of life.
Remember that Wegener used the similarity of the mountains on the west and east sides of the Atlantic as evidence for his continental drift hypothesis. Those mountains rose at the convergent plate boundaries where the continents were smashing together to create Pangaea. As Pangaea came together about 300 million years ago, the continents were separated by an ocean where the Atlantic is now. The proto-Atlantic ocean shrank as the Pacific Ocean grew. The Appalachian mountains of eastern North America formed at a convergent plate boundary as Pangaea came together (Figure 1.1). About 200 million years ago, the they were probably as high as the Himalayas, but they have been weathered and eroded significantly since the breakup of Pangaea. Pangaea has been breaking apart since about 250 million years ago. Divergent plate boundaries formed within the continents to cause them to rift apart. The continents are still moving apart, since the Pacific is shrinking as the Atlantic is growing. If the continents continue in their current directions, they will come together to create a supercontinent on the other side of the planet in around 200 million years. If you go back before Pangaea there were earlier supercontinents, such as Rodinia, which existed 750 million to 1.1 billion years ago, and Columbia, at 1.5 to 1.8 billion years ago. This supercontinent cycle is responsible for most of the geologic features that we see and many more that are long gone (Figure 1.2). Scientists think that the creation and breakup of a supercontinent takes place about every 500 million years. The supercontinent before Pangaea was Rodinia. A new continent will form as the Pacific ocean disappears. Click image to the left or use the URL below. URL:
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plate tectonics explains
a) why mountain ranges are located where they are. b) why certain regions may have deadly, mild, or no volcanic eruptions. c) why many ore deposits are located where they are. --> d) all of the above
how could plate tectonics movements affect the evolution of life?
a) two continents split apart and one species evolves into two different species, one on each continent. b) two continents come together so the organisms of two separate species compete until only one species remains. c) two continents split apart and the organisms of one species stay exactly the same. --> d) all of the above
the name of the supercontinent that came together 300 million years ago.
a) eurasia --> b) pangaea c) aegean d) rodinia
the appalachian mountains may have been as high as the himalaya because they formed from the same plate tectonics processes.
--> a) true b) false
pangaea was the first supercontinent in earth history.
a) true --> b) false
as continents come together to form a supercontinent,
a) the ocean that had separated them disappears. b) a giant ocean forms on the outside of the supercontinent. c) mountain ranges rise where continental plates converge. --> d) all of these.
predictions for the future of the continents include
a) staying in their current locations. b) turning the continents around to form a supercontinent like rodinia. --> c) closing the pacific ocean and creating a supercontinent on the opposite side from d) all of these.
continents come together and break apart in a cycle called the
--> a) supercontinent cycle b) plate tectonic cycle c) continental drift cycle d) pangaea cycle
continental drift and seafloor spreading together make up plate tectonics.
--> a) true b) false
a new supercontinent forms about every 500,000 years.
a) true --> b) false
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