This news article discusses data on Jupiter's moon Europa returned by NASA's Galileo and Voyager spacecraft and the possibility that an ocean of liquid water might exist on Europa and, with it, the possiblilty for extraterrestrial life. Full description.

This learning system provides a variety of materials on Earth and space sciences, such as images, movies, animations, and data sets. Students, teachers, and the general public can access information on the sun and space weather, astronomy, our planet and solar system, current space missions, space-related mythology and art, and geology. For teachers, there are links to tools for navigating the site, ... Full description.

This document outlines the development of the theory of contintental drift and how many lines of evidence collected over several decades by various researchers were brought together to explain how the seafloor spreads and the continents move about. Links to additional information are included. Full description.

Users can access a selection of technical information and data about earthquakes in the U.S. and around the world. A current worldwide list of earthquakes is available, as are data on geophysical solutions, a catalog search, an automatic data request function, mining seismicity information, and a registry of seismograph stations. Full description.

This article describes how students in Alaska are helping scientists study earthquake hazards by conducting global positioning system (GPS) measurements in order to track crustal movements in the Earth's crust. It points out the importance for Alaskan inhabitants of understanding the hazards and physical processes associated with earthquakes, describes how the students located and installed a network ... Full description.

This animation illustrates how tsunamis can be caused by underwater earthquakes, which are frequently located at subduction zones where oceanic plates are slipping under continental plates. Full description.

This biography of Admiral Harry Hess details his career in the United States Navy, during which he collected data on the seafloor, and as a geologist, in which he incorporated his observations on seafloor features into a hypothesis that the seafloor was spreading. Full description.

This page consists of two maps of the world, showing how earthquakes define the boundaries of tectonic plates. Volcanoes are also distributed at plate boundaries (the "Ring of Fire" in the Pacific) and at oceanic ridges. It is part of the U.S. Geological Survey's Cascades Volcano Observatory website, which features written material, images, maps, and links to related topics. Full description.

In this activity, the Earth's crust and mantle are compared to the shell and insides of a boiled egg. A computer simulation is provided in which students can click and drag crustal "plates" to form various types of plate boundaries. Brief descriptions of the boundary types accompany the simulation. Full description.

This webpage is part of NASA's Visible Earth, a searchable directory of images, visualizations, and animations of Earth. It features remotely sensed imagery of volcanic eruptions that display smoke plumes, lava flows, fires, and other eruptive features. Each image is accompanied by a caption describing the subject being illustrated and the satellite or instrument which captured the image. Files are ... Full description.