Thursday, 2/18

Bell Ringer

Lesson - Continuing Plate Tectonics

Quiz

Exit Ticket

Many geologic processes and features, such as tectonic plate motion, volcanic activity, and geysers, are related to the Earth's internal heat.

The diagram below two ways to classify Earth's layers. One way, shown on the left, is based on composition (what the layers are made of). The other way, shown on the right, is based on mechanical properties of the layers (such as solid vs. liquid and rigid vs. soft).

Warmer parts of a fluid tend to rise, while cooler parts tend to sink. This results in convection currents that help distribute heat more evenly throughout the fluid.

Convection can also occur in some solids. The asthenosphere is a layer of solid rock, but the pressure and temperature conditions allow the rock to flow. 

In the asthenosphere, hotter rock rises and cooler rock sinks, which creates convection cycles, or currents.

 These cause changes in the lithosphere, including the movement of plates and seafloor spreading.

The movement of Earth's tectonic plates relates to many factors, including convection cycles and density differences between the plates. 

Tectonic plates are part of the lithosphere, which is rigid and does not flow. The image shows a cross section through the Earth's interior.

Tectonic plates of the lithosphere are shown in grey at the Earth's surface. The Earth's asthenosphere is shown in red-orange. 

Black arrows in the lithosphere show the directions in which the plates move. Red arrows in the asthenosphere and the rest of the mantle represent convection currents.

The movement of Earth's tectonic plates relates to many factors, including convection cycles and density differences between the plates. 

Tectonic plates are part of the lithosphere, which is rigid and does not flow. The image shows a cross section through the Earth's interior.

There are three types of plate boundaries: divergent, convergent, and transform

The type of boundary formed by two plates depends on the motions of the plates.

Divergent boundaries -- where new crust is generated as the plates pull away from each other. 

Convergent boundaries -- where crust is destroyed as one plate dives under another. 

Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other.