Here are some links to some general Geology and Earth Science websites that you might find interesting.
Geology & Earth Science Dictionary
National Parks Service: Geologic Time
The Virtual Cave
Face of the Earth
Adventures at Dry Creek
Above, Bill Nye explains the Richter Scale used for measuring the magnitude of earthquakes.
Below is a link to help us learn about the Richter and Mercalli Scales.
Richter & Mercalli Scales
Bill Nye explains how Seismometers and Seismographs work.
Below is a website with instructions for making a simple seismograph.
Make a Seismograph