Finding identical or similar fossils in areas separated by vast distances were some of the first clues that scientists used to reconstruct past plate movement.
This distribution of fossils led to theories that the southern continents were once joined in a supercontinent called Gondwana. Similar geologic formations on different continents show historic land connections. If Southern Hemisphere continents were reassembled into a single landmass, glacial remnants in Africa and India would realign.
This material is also available as a free iBooks textbook and iTunes U course. Get a new perspective on earthquakes with this rich collection of multimedia resources. You'll learn why earthquakes happen, how they've shaped the Bay Area, and what you can do to prepare for the next one. Find out what you can do right now to protect yourself in the event of an earthquake.
You'll be happy you did. Sign up for event updates and exciting announcements. Learn more. Reservations are required for the planetarium and are available on a first-come, first-served basis.
More info. Two things are necessary for earthquakes to occur: 1 motion within the Earth that stresses and deforms material; and 2 material that deforms by breaking rather than flowing. Moving plates of cold, brittle lithosphere produce most earthquakes, especially where they are contorted and grind against one another along their boundaries.
Plate Tectonics and Our National Parks. Divergent Plate Boundaries. Convergent Plate Boundaries. Transform Plate Boundaries. Oceanic Hotspots. Continental Hotspots. Text and Illustrations by Robert J. Explore This Park. Evidence of Plate Motions. The plates rip apart at divergent plate boundaries, crash together at convergent plate boundaries, and slide past each other at transform plate boundaries.
The Action is at The Edges So why is there so much tectonic activity earthquakes, volcanic eruptions and the formation of mountain ranges in the western United States compared to the East?
In , after many years of research, Alfred Wegener proposed that the continents drifted across the Earth. His evidence included the fact that the continents seem to fit together, and similar fossils and glacial patterns were found on two different continents. Despite this evidence, he could not figure out what was causing this movements of the continents. Unfortunately, Wegener passed away before any new discoveries were made about the mechanisms behind this movement of continents across the ocean.
New theories started to arise as more evidence was collected.
0コメント