Sunday, October 21, 2012

Plate Tectonics

For today's posting I'll give you a glimpse of some of the information that I'm including in the online rockhounding adventures. During the creation of the segments for the adventures I have created graphics, movies, and animations when ever possible. It has been a real challenge to learn about the world of digital video.  The software that I am using to actually produce the online rockhounding adventures is very specific and limited in the video formats that it accepts.  So in almost every case I have to produce the videos with one type of software and then convert it with another piece of software so that I can use the videos in the adventures.  I have also figured out how to add music.  It is useful that I found a web page that has copyright free music including some that are designed to be used as background for video clips.

In the last segment of the first adventure, which covers Earth Formation, I created the following movie clip to illustrate the Earth's crustal plates.

video

The process of plate tectonics involves the large scale motions of the Earth’s crust.  The crust and the portion of the mantle connected to it (lithosphere) are broken up into several large and many minor plates. These crustal sections ride and float on top of the molten portion of the mantle (asthenosphere).. There are actually two types of crust that make up these plates.  There is the lighter and thicker continental crust and the denser and thinner ocean crust.  The ocean floors are continually moving, spreading from the mid-ocean ridges, sinking at the edges, and being regenerated. Convection currents beneath the plates move the crustal plates in different directions. The source of heat driving the convection currents is radioactivity deep in the Earth’s mantle.

The movement of the Earth's plates  explains the cause of earthquakes, volcanoes, oceanic trenches, mountain range formation, and many other geologic phenomenons. The plates are moving at a speed that has been estimated to be up to six inches per year (15 cm) depending on the plate, but averages around an inch and a half (3.8 cm).  

This is just a sample of the informatoin included in the online rockhounding adventures.  The references for this sample are: 
 

 http://www.ucmp.berkeley.edu/geology/tecmech.html
http://www.enchantedlearningshtml
Music from http://freemusicarchive.org Tom Fahy: Lullaby for Little Rachel

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