Stemscopedia: Plate Tectonics Name_________________
Table of Contents
Analyze and interpret data on the distribution of fossils and rocks, continental shapes, and seafloor structures to provide evidence of the past plate motions.
Earth’s Interior Name______________
Page Number: ______
Bell Work: Why Does the Earth Have Layers Video
Label the Earth’s Interior
Have you ever wondered how mountains ___________________? What about forces of nature such as __________________ or earthquakes? The answers to these questions are found in the ___________________of Earth and the concept of plate tectonics!
The _________________ is the top layer of Earth’s surface, and the ________________ is the center layer. A thick layer of ____________________ rock can be found between the crust and core. This layer of molten rock is known as the __________________. The ____________________ is made up of Earth’s crust and the _________________________ part of the mantle. Cool and _______________, the lithosphere is the outermost layer of Earth and ______________________ into large, thick pieces called tectonic __________________. These tectonic plates contain different kinds of crust, _________________________________________. Both are ______________ dense than the mantle, but oceanic crust is ____________________ than continental crust. This is one reason why continents are ____________________than the ocean floor. However, some continental plates are ______________________in the ocean, and some _________________ plates, such as the entirety of Iceland, are above the ocean.
lithosphere: consists of the crust (light brown) and upper mantle (dark brown)
molten: melted; liqueed
tectonic plates: the broken pieces of the lithosphere that move on the asthenosphere.
Scientists have given _______________to Earth’s tectonic plates. This map shows the current major tectonic plates. Many of these plates are named for the continents or oceans they _______________. Maps of ancient land and water patterns show how Earth’s plates have moved ______________ _________________, ____________________, and spread apart.
How did they ______________________ that the tectonic plates had moved? Was that movement related to Earth __________________________ such as mountains, valleys, or volcanoes?
Look at the world map and notice the shapes of the continents. Do you see how some continents appear to ___________ together like the pieces of a jigsaw puzzle?
Why do you think this is?
Is it just a coincidence or do you think it suggests something important about the history of our planet?
What Do You Think?
If you noticed that the continents appear to tit together like a______________________________, you’re not alone. In the early 20th century, a German scientist named __________________ ____________________noticed this phenomenon. Wegener hypothesized that at one or more points in Earth’s history, the continents were__________________. Wegener looked for further _____________________that the continents might have been connected and might have moved over time.
Evidence of Continental Movement
Matching geologic structures:
Wegener looked for other connections between the matching ____________________. Where coastlines appeared to fit together, he noticed that certain _______________________________ also appeared to fit together. For example, a _________________________on one coastline appeared to connect with a mountain chain on the______________________ coastline. Several deposits of sediment left behind by ___________________ also lined up along the matching coastlines of continents.
In addition to geological evidence, Wegener found ____________________evidence that the continents may once have been connected.
Fossils of a freshwater ________________ called Mesosaurus were found on both the eastern coast of South __________________and the western coast of South ________________. It is highly unlikely that these __________________ animals swam across the entire Atlantic Ocean while they were alive.
Fossils of a ______________ reptile called Lystrosaurus were also found along matching coasts of eastern _________________, central India, and __________________. These land animals also could not have crossed the oceans separating these continents. Equally unlikely is the possibility that the same species ___________________ independently on multiple ___________________. Instead, Wegener reasoned that the continents must have been ___________________at one time. As the continents __________________________ they took mesosaurus and lystrosaurus fossils with them.
Wegener concluded from his ____________________ that the continents must move over time. Scientists gave the process its more familiar name: _______________________________. At least once in Earth’s history, the continents were connected in large __________________________, or supercontinents. Around ________________million years ago, all the continents were connected in one giant ___________________________. Wegener named this supercontinent _________________________ which means “all the Earth”. Over millions of years, the continents moved __________________to their present-day positions.
Despite the evidence Wegener collected, he could not provide a theory explaining _____________ the continents moved over time. Partly for this reason, his hypothesis was initially _______________ by the scientific community. Then, in the 1940s, scientists discovered new evidence concerning __________________________ that suggested how continents drift. Unfortunately, Wegener did not live to see his work validated. He froze to death on an expedition across the Greenland ice cap, trying to prove his hypothesis.
Just below the __________________ is a shallow layer of mantle called the asthenosphere. The partially molten rock in the asthenosphere moves slowly due to a process called ________________. Tectonic plates of the lithosphere _____________________ on top of the asthenosphere, as they are less ___________________ than the material of the asthenosphere.
Convection is the process by which hot material ______________ and cooler material ___________. The molten material of the ______________ found deep within Earth heats up and begins to ____________ toward the crust. As the material gets closer to the crust, it ___________________ down in the asthenosphere, the uppermost layer of the mantle. As it cools, it __________________ back toward the core. Eventually, the sinking material heats up and rises again. This produces ____________________movements called convection currents. Tectonic plates float on top of the ______________________________ as it moves. The asthenosphere is a part of the mantle that is not in the _____________________ state. The asthenosphere is solid, but it has ______________. Plasticity is the condition of a solid that allows it to flow like ____________________________
Convergent Boundaries (Ms. Pope Presents)
Divergent Boundaries: form where ocean plates ___________________________ (Mid-Atlantic Ridge)
Transform Boundaries: form where one plate _______________ past another (San Andreas Fault)
Complete the diagram of seafloor spreading as the teacher leads the discussion.
Convergent Boundaries: Subduction Zones
Tectonic plates are constantly___________________. At different times, some plates move faster than others. However, even the fastest plates move only tens of__________________ every year. Tectonic plate boundaries are places where the _______________of two or more plates interact. At some boundaries, plates move apart, such as along the ______________________________ that passes through the middle of the Atlantic Ocean and through the middle of Iceland. The North American Plate moves westward, while the Eurasian Plate moves in the opposite direction, splitting that country apart. As the asthenosphere moves, tectonic plates move with it in _________________ directions. Scientists explain this process through the theories of plate tectonics and seafloor spreading.