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 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.

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 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 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.

This archived Universities Space Research Association Earth Science Picture of the day highlights the Dent de Morcles geologic formation. The photo shows an example of the complex processes that often take place during mountain building. For more information about the Dent de Morcles, geology of Switzerland and mountain formation, users can follow links to external pages from this Picture of the Day. ... Full description.

This activity leads students through the process of creating a geologic map and cross-section in a small area of horizontal sedimentary rocks that are exposed in a few locations. On this Starting Point page, users can access information about the exercise's learning goals, context for use, teaching notes and tips, teaching materials, assessment ideas, references and topics covered. Full description.

This homepage of Steve Reynolds, geology professor at Arizona State University, contains numerous color photographs, 3D imagery and animations, and information about the geology of Arizona. Features of the site include photographs, composite digital and satellite imagery, and topographic images that illustrate various aspects of geology. In order to visualize geology and topography in 3D, there are ... Full description.

This virtual five-day field mapping project allows students to construct a geological map from data provided by the web site. Students collect geologic, structural, paleontologic, strain and microstructural data observed at specific localities. Students are then able to derive a structural history for the area, including a field map, stereographs, and deformation plots. The site contains photographs ... Full description.

This interactive tutorial is designed to help students visualize geologic features. The site contains many animated block diagrams that show how the surface expressions of dipping layers, folds, igneous intrusions, and faults are related to subsurface structure and cross sections. Blocks may be rotated, eroded, and made partially transparent by moving the mouse. There are also questions and blank ... Full description.