Users can search the large number of the U.S. Geological Survey's web pages with this engine. In addition to the search box (where a key word or title can be typed), the search is further refined by the incorporation of links to categories of topics. The topics consist of resource types such as Fact Sheets or Maps, subjects such as minerals or water quality, or an organizational search on USGS State ... Full description.

This GIF image is part of the U.S. Geological Survey's Cascades Volcano Observatory website, which includes pictures (archived and real-time), written reports, seismic data, and other materials on volcanology, including a glossary and links to other relevant sites. These images show Mount St. Helens while it was erupting on May 18th, 1980. Full description.

This collection of images shows geologic features in many of the country's national parks. The collection is searchable by park name, state, year, or by the name of the photograph. Each photo is accompanied by a brief caption that provides the photographer's name, the date, and a description of the photo. Full description.

This poster of Mars shows a full-disk mosaic, taken by the Mars Global Surveyor. The northern polar ice cap, Tharsis volcanoes, and Valles Marineris are visible. The accompanying text provides a brief description, history, and geology, as well as some statistical facts and significant dates in Mars exploration. Full description.

This text explains how glaciers scour and grind the Earth's surface, and about the sorts of deposits they leave behind. Emphasis is on glaciation in the mountains and valleys of Vermont. Links to related topics are included. Full description.

Visitors to this site can access general information about earthquakes, such as frequently asked questions, seismic hazards, and building code information. Real-time information on specific events in western Canada is available in the form of maps and lists, and is updated hourly. For teachers, there is a set of links to background materials, computer and classroom activities, and seismic data. A ... 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.

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 is a photograph of the 18 May 1980 explosion of Mount St. Helens. Links to other volcano images and related topics are included. Full description.

This site explains how core samples are taken from the ocean floor. Topics include how research cruises are planned, who makes up the crew of a research vessel, and what a cruise track is. Links to additional information are embedded in the text. Full description.