This demonstration models the manner in which the convection currents in the mantle of the Earth cause movement of the plates. Convection currents in the mantle were thought, for many years, to be solely responsible for plate tectonic movements, with the movement taking rocks down at destructive margins and new rocks forming when plates spread. It is now thought likely that there are three possible ... Full description.

In this activity students are asked for their predictions about how different water temperatures will affect movement in the ocean water column. Students will investigate the effect of water temperature on mixing in the water column. They will half fill one jar with the hottest water the faucet will provide and half fill the other jar with chilled water. After allowing the water in both jars to settle ... Full description.

This article explains the difference between the three South Poles. It describes the south magnetic dip pole which is not even on the Antarctic continent, the ceremonial South Pole, and the Geographic South Pole, the marker of which is constantly on the move. The article also explains why the Geographic South Pole is resurveyed each year and the difference between the Chandler wobble and the precession ... Full description.

In this activity, students will gain an understanding of how geologists determine rates of sea floor spreading between two tectonic plates. Using a strip map of the North Atlantic seafloor, they will measure distances and note the ages of the strips of seafloor basalt. They will also gain experience applying some basic, useful mathematical concepts such as the calculation and use of velocities and ... Full description.

Before the 17th century, people generally believed that Earth was at the center of the universe, a system originally developed by Ptolemy. Galileo, however, was not afraid to challenge existing beliefs when he published his work in support of the Sun-centered, or heliocentric, theory developed by Copernicus. This video segment describes the two opposing worldviews and Galileo's observation that Venus ... Full description.

In this earthquake safety classroom activity, students work in teams to build seismic safe structures. Students will try building their own structure to see if they can discover some of the features that minimize the effects on a building when the Earth shakes. Each team will build and test three structures following the instructions. After all teams finish, the class discusses features of seismic ... Full description.

At this site the question and answer format is used to provide information about the Earth's magnetic field. Frequently asked questions are linked to detailed answers. Along with standard questions about the magnetic poles and how a compass works, there are sections about geomagnetic models, Space Weather Scales and magnetic field reversals. Links lead to a site to download the latest model as well ... Full description.

This page points to a number of reports and maps on earthquake hazards, prediction, and preparedness. The page is mainly about Northern California including the San Francisco Bay area, but also including some items on Southern California and Alaska, as well as general articles on the topics. Map types include seismic hazards maps, shaking hazards maps, and shaking intensity maps. Related programs ... Full description.

This site provides a complete and comprehensive center for students to learn about rivers. Animated pages about erosional processes, river volume, velocity, and transport are available for students to print or take notes on. Case studies on the Singapore River and Rhine River are presented with pictures. On-line worksheets cover erosion, deposition, and river patterns. An on-line study guide summarizes ... Full description.

This Why Files article investigates the possibility of asteroid impacts on Earth. The feature covers what asteroids are, why their orbits change to hit planets, and major impacts from Earth's past. Could a major impact have killed off the dinosaurs? What is the likelihood of a large 'global killer' asteroid striking in the near future? These questions became popular with the advent of impact movies ... Full description.