Is glacier ice a type of rock?
Glacier ice, like limestone (for example), is a type of rock. Glacier ice is actually a mono-mineralic rock (a rock made of only one mineral, like limestone which is composed of the mineral calcite). The mineral ice is the crystalline form of water (H2O). It forms through the metamorphism of tens of thousands of individual snowflakes into crystals of glacier ice. Each snow flake is a single, six-sided (hexagonal) crystal with a central core and six projecting arms. The metamorphism process is driven by the weight of overlying snow. During metamorphism, hundreds—if not thousands—of individual snowflakes recrystallize into much larger and denser individual ice crystals. Some of the largest ice crystals observed at Alaska’s Mendenhall Glacier are nearly one foot in length.
Learn more: USGS Water Science School - Glaciers: Things to Know
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Fifty years of U.S. Geological Survey (USGS) research on glacier change shows recent dramatic shrinkage of glaciers in three climatic regions of the United States. These long periods of record provide clues to the climate shifts that may be driving glacier change. The USGS Benchmark Glacier Program began in 1957 as a result of research efforts...
Satellite image atlas of glaciers of the world -- North America
Williams, Richard S.; Ferrigno, Jane G.
Glaciers: A water resource
Most Americans have never seen a glacier, and most would say that glaciers are rare features found only in inaccessible, isolated wilderness mountains. Are they really so rare? Or are they really potentially important sources of water supply?
Meier, Mark; Post, Austin
Fifty Years of Glacier Change Research in Alaska
ANCHORAGE, Alaska — This year marks the 50th anniversary of one of the longest continuous glacier research efforts in North America.
From Icefield to Ocean - What Glacier Change Might Mean for the Future of Alaska
Frozen bodies of ice cover nearly 10 percent of the state of Alaska, but the influence of glaciers on the environment, tourism, fisheries, hydropower, and other important Alaska resources is rarely discussed.
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The great majority of the world’s glaciers appear to be declining at rates equal to or greater than long-established trends, according to early results from a joint NASA and United States Geological Survey (USGS) project designed to provide a global assessment of glaciers. At the same time, a small minority of glaciers are advancing.
Microstructures of an ice core
Characterization of the microstructures of an ice core reveals the mechanisms by which large bodies of ice deform and flow.
Coring on the Juneau Icefield, Alaska
An ideal ice core site is the highest, flattest glacier in a region. In 2016, a transect of 7-9 m ice cores was drilled on the Matthes Glacier, Juneau Icefield to determine if recent fires are affecting the glacier surface. (Photo: Lucas Foglia, used with permission)
Crevices on glacier, Juneau Icefield
Crevices on glacier, Juneau Icefield
Juneau Icefield
Photograph of the Juneau icefields of southeastern Alaska that contain more than 140 glaciers which extend over 1,500 square miles (3,900 square km). Fieldwork in Alaska for the Terrestrial Records of Holocene Climate Change project from July 29 to August 10, 2016.
Sea ice in the Chukchi Sea, Alaska
Sea ice in the Chukchi Sea in 2013.
Ice bubbles and crystals
A wealth of information on past climates is contained in both the trapped air bubbles and ice grains of polar ice sheets.
Tracking Pacific Walrus: Expedition to the Shrinking Chukchi Sea Ice
Summer ice retreat in the Chukchi Sea between Alaska and Russia is a significant climate change impact affecting Pacific Walruses, which are being considered for listing as a threatened species. This twelve minute video follows walruses in their summer sea ice habitat and shows how USGS biologists use satellite radio tags to track their movements and behavior. The
Louis Sass with an ice core in a snow pit
Louis Sass with an ice core in a snow pit
Ice Core
Mikhail Kanevsiy (University of Alaska, Fairbanks) holding a core of ice-rich permafrost from about 2m depth.
Drilling firn cores on the Juneau Icefield, Alaska
Molly Peek and Chris Miele drilling and processing firn cores on the Juneau Icefield, Alaska.