Plate tectonics Theory

Plate Tectonics Theory

True or False​

Multiple Choice

Plate tectonics is a section of the lithosphere that slowly moves over the asthenosphere, carrying pieces of continental and oceanic crust.

• TRUE

• FALSE

Multiple Choice

Convection currents in the mantle move the plates as the core heats the slowly-flowing asthenosphere.

• TRUE

• FALSE

Multiple Choice

The edges of Earth’s plates meet at plate boundaries.

• TRUE

• FALSE

Multiple Choice

The transform plate boundary is a plate boundary where two plates move away from each other.

• TRUE

• FALSE

Multiple Choice

Rifting causes seafloor spreading.

• TRUE

• FALSE

Multiple Choice

The geologic features in divergent plate boundaries are volcanic arcs and trenches.

• TRUE

• FALSE

Multiple Choice

The stress in boundaries between two plates that are colliding is called shearing

• TRUE

• FALSE

Multiple Choice

In 1960, a German scientist called Alfred Wegener proposed that South America and Africa were once joined together and had subsequently moved apart.

• TRUE

• FALSE

Multiple Choice

All the continents were once joined together as one big land mass called Pangaea.

• TRUE

• FALSE

Multiple Choice

Similar pattern of rock layers on different continents is evidence that the rocks were once close together or joined.

• TRUE

• FALSE

Continental Drift Theory to

Plate Tectonics Theory​

​Before PTT

• ​Shrinking Earth Hypothesis

• ​Expanding Earth Hypothesis

• ​Continental Drift Theory

• ​Seafloor Spreading Hypothesis

​PANGAEA

• ​Alfred Wegener

• ​1920

• ​"All Earth"

• ​Continental Drift Theory

​CONTINENTAL JIGSAW PUZZLE

• ​1965

• ​Sir Edward Bullard

• ​best fit occurs along the continental margin or at the depth of about 2000m

​Fossils

​Rocks

• ​Appalachian Mountain Range - terminate abruptly

• ​mountains of the same and structures are also found in Eastern Greenland, Ireland, Great Britain, and Norway

• ​trending mountain belts Argentina match closely with Cape Mountains in South Africa

​Glacial

• ​Glacial Deposits in the southern hemisphere

• ​Layers of till (sediments deposited by glaciers) and striation (scratch match) in bedrock

​Coal Deposit

• ​Coal beds in Antartica

​Drawback

​No enough evidence on how continents moved.

​1957-1958​

International Geophysical year​

​Seafloor Topography

​Continents fit together along the edges of their continental shelves. Mid-ocean ridges and deep-sea trenches develop at the boundaries of the moving plates. Volcanic islands and seamounts develop where a plate moves over a stationary hotspot.

​Earthquake and Volcanic Activity

​Most earthquakes and volcanoes occur where the moving plates interact along their boundaries, and at hotspots.

​Evidence for Tectonic Plates

​The continents are blocks of thick crust that are passengers on the tops of large tectonic plates that move over the asthenosphere. Earthquakes, mountain building and volcanic activity occur mostly at the boundaries of the moving plates. Only shallow earthquakes occur where plates diverge at mid-ocean ridges, whereas earthquakes extend to great depth where plates converge at subduction zones.

Plate Tectonics Theory

• ​a unifying theory, which explains many features and processes that we find on the Earth

• World-Wide Standardized Seismograph Network