Geology

[equalsmcsquared.livejournal.com]

*In Geology today the students will be learning about plate tectonics.*

Good morning, *Sara says, looking around the class.* I trust you all had either a restful or eventful weekend. Hangover remedy is on the counter by the door, along with energy bars. Please sign the roll sheet before you leave.

Today, we will be discussing plate tectonics. If you will open the handouts I've passed around.

The plates consist of an outer layer of the Earth, the lithosphere, which is cool enough to behave as a more or less rigid shell. Occasionally the hot asthenosphere of the Earth finds a weak place in the lithosphere to rise buoyantly as a plume, or hotspot.
Only lithosphere has the strength and the brittle behavior to fracture in an earthquake.

The map below locates earthquakes around the globe. They are not evenly distributed; the boundaries between the plates grind against each other, producing most earthquakes. So the lines of earthquakes help define the plates...

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[miss-thomasina.livejournal.com]

Thomasina gets to class on time, signs her name on the roll sheet and takes her seat at the table she shares with tru_relivesdays. Then she does as Ms. Sidle has directed and opens the handout before settling in to take notes in her exercise book, wondering more than a little at the idea of the ground deciding to move beneath one's feet even a little, much less to so great an extent as the lecture and the pictures in the handout would seem to indicate.

[equalsmcsquared.livejournal.com]

*Plate tectonics can be a frightening reality, as the recent tsunami demonstrated. And yes, Sara is also including news reports and footage of that incident in today's lecture.*