This United States Geological Survey (USGS) on-line publication discusses volcanic ash fall in terms of composition and effects. This report discusses the negative effects of volcanic ash fall on machinery, human health, weather and man-made structures, using the Mount Saint Helens eruption of 1980 as an example. The composition of volcanic ash is discussed, as well as ancient and modern ash falls ... Full description.

This article provides an overview of the sedimentary processes that occurred in the aftermath of the May 18, 1980 eruption of Mount St. Helens. Topics include the vast quantity of easily erodable volcanic deposits, high sedimentation rates downstream from the volcano, changes in drainage patterns caused by the debris avalanche that triggered the eruption, and some efforts to control the downstream ... Full description.

This Why Files short article discusses some new research on Yellowstone Caldera, a giant volcanic hotspot in Wyoming. Rock has been remelted inside the caldera. Using highly sensitive techniques to extract data from almost microscopic zircon crystals, two geologists at the University of Wisconsin-Madison found that over the past 2 million years, the giant Yellowstone volcano erupted at 700,000-year ... Full description.

This resource presents three examples of lava domes, from Alaska, Japan, and Saudi Arabia, along with a 3D simulated view of Mt. St. Helens' lava dome. A diagram shows the progressive growth of Mt. St. Helens' lava dome from 1980 to 1983. A link leads to a thorough explanation of dome-collapse pyroclastic flows (nuee ardentes) and another leads to a numerical program of lava dome growth. Full description.

This United States Geological Survey (USGS) website explains volcanic gases and their effects on the Earth and its life. The report discusses gases trapped in magma below the Earth's surface as the driving force of volcanic eruptions. Types of gases, such as sulfur dioxide and carbon dioxide, and their potential effects are described. A comparison of volcanic gas composition in three different volcano ... Full description.

These lecture notes provide an introduction to igneous rocks. The notes cover information about characteristics of magmas, plutonic rocks, volcanic rocks, and textures of igneous rocks. There are several illustrations within the text. This resource is part of the Teaching Petrology collection. http://serc.carleton.edu/NAGTWorkshops/petrology03/index.html Full description.

This module offers an introduction to the concepts explored by Alfred Wegener, Harry Hess, and others. It is the first in a series on plate tectonics. Full description.

This site contains an introduction to the main features of the geology of Iceland, an interactive map, a virtual field trip of the volcanic eruptions of southern Iceland, Dewey classified links related to Icelandic earth science, a bibliography of news sources and journals, and links to Icelandic earth science institutions. 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 United States Geological Survey (USGS) fact sheet is designed to educate visitors about safety in preparation for visiting Kilauea Volcano in Hawaii. This volcano has been erupting almost continuously since 1983 and is noted for its approachable lava flows; however, it undergoes many changes that can be unpredictable and life threatening. Topics include volcanic hazards such as bench collapse, ... Full description.