This topical directory provides an alternate way to browse United States Geological Survey (USGS) science programs and activities. It is not an exhaustive list of all USGS science topics but provides a categorization using a thesaurus of related terms that will give definitions, links to science content, and a structured approach to discovery. The directory is divided into fourteen major topic headings, ... Full description.

This lesson introduces J. J. Thomson's discovery of the electron and E. Rutherford's planetary model of atomic structure. This is the first in a series covering modern atomic theory. Full description.

In this activity students test soil samples for percent composition of air, water, organic material, and minerals. They will record the data on their data sheet or in a notebook. Students will understand the four basic soil components and realize that these components can vary widely within a small geographic area. Full description.

This resource explains how the oceans became salty. Topics include the source of the salt, how rainwater dissolves rock and carries the material away as dissolved ions, and the two most common ions in seawater. A link to additional information is also provided. Full description.

This set of lecture notes discusses the occurrence and tectonic settings of igneous rocks near convergent plate margins. A discussion of petrography includes major element composition, calc-alkaline trends in ternary diagrams, trace element variations, isotopes to distinguish magma sources, and the origin of igneous rocks at convergent margins. The lecture notes include helpful illustrations, maps ... Full description.

This Why Files feature posted November 6, 1997 explains some of the tools employed by the climatologist, and how they are used to measure climate or look back in time to see what climate was like long ago. How do scientists forecast what might be in store for the planet? Topics include how scientists take the Earth's temperature and use computer-based climate models, ice cores from remote glaciers ... Full description.

In July 1991, the alignment of the Sun, Moon, and Earth produced a total solar eclipse with a particularly long duration and a path that crossed easily accessible locations, including a major astronomical observatory in Hawaii. This video segment explains the mechanics of solar eclipses and shows the rare 1991 eclipse from the top of Mauna Kea. The segment is five minutes seven seconds in length. ... Full description.

This National Oceanic and Atmospheric Administration (NOAA) site presents video animations and maps of exploration routes, bathymetry, undersea tracks of submersibles, satellite imagery, aerial photography. The section of animated images includes a three-dimentional flythrough created by using bathymetric data, video animations of a mid-ocean spreading center, an animation of the subduction zone, ... Full description.

This web site is a good place to start for anyone seeking information on the geology and management of natural hazards phenomena related to volcanoes and hydrologic and geothermal processes. Some information is included on landslides, earthquakes, faults, and tsunamis. In addition to a brief definition of the terms, the site provides background information on related terms; maps, graphics and images; ... Full description.

This web page covers the progress of the early 1960 Kapoho eruption of Kilauea Volcano, Hawaii, and the damage it caused. The eruption caused havoc in lower Puna, an idyllic rural paradise until the lava fountains and flows covered farm land and villages including Kapoho Village and parts of Koa`e Village. During this time, the volcano's summit deflated and eventually collapsed. This page is part ... Full description.