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). Most glacier ice 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.

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Are today's glaciers leftovers from the Pleistocene ice age?

Yes and no. It depends on which glaciers you are considering. Parts of the Antarctic Continent have had continuous glacier cover for perhaps as long as 20 million years. Other areas, such as valley glaciers of the Antarctic Peninsula and glaciers of the Transantarctic Mountains may date from the early Pleistocene. For Greenland, ice cores and...

How old is glacier ice?

The age of the oldest glacier ice in Antarctica may approach 1,000,000 years old The age of the oldest glacier ice in Greenland is more than 100,000 years old The age of the oldest Alaskan glacier ice ever recovered (from a basin between Mt. Bona and Mt. Churchill) is about 30,000 years old. Glacier flow moves newly formed ice through the entire...

Do ice worms exist?

Yes, ice worms do, in fact, exist! They are small worms that live in glacial ice in Alaska, Washington, Oregon, and British Columbia; they have not been found in glaciers elsewhere. Contrary to stories and songs, they do not give glacier ice its blue color and they don't grow to lengths of 50 feet. (These myths were made popular by poet Robert...

Why is glacier ice blue?

Glacier ice is blue because the red (long wavelengths) part of white light is absorbed by ice and the blue (short wavelengths) light is transmitted and scattered. The longer the path light travels in ice, the more blue it appears. Learn more: USGS Water Science School - Glaciers: Things to Know

How much of the Earth's water is stored in glaciers?

About 2.1% of all of Earth's water is frozen in glaciers. 97.2% is in the oceans and inland seas 2.1% is in glaciers 0.6% is in groundwater and soil moisture less than 1% is in the atmosphere less than 1% is in lakes and rivers less than 1% is in all living plants and animals. About three-quarters of Earth's freshwater is stored in glaciers...

How would sea level change if all glaciers melted?

There is still some uncertainty about the full volume of glaciers and ice caps on Earth, but if all of them were to melt, global sea level would rise approximately 70 meters (approximately 230 feet), flooding every coastal city on the planet. Learn more: USGS Water Science School: Glaciers and Icecaps National Snow and Ice Data Center: Facts about...

How do we know glaciers are shrinking?

Repeat photography and aerial / satellite photo analysis provide evidence of glacier loss in terms of shape and area. The USGS Benchmark Glacier project has collected mass balance data on a network of glaciers in Alaska, Washington, and Montana for decades, quantifying trends of mass loss at all sites. Extensive field data collection at these...
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Date published: September 28, 2016

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.

Date published: March 18, 2015

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.

Date published: May 29, 2002

Decline of World's Glaciers Expected to Have Global Impacts Over This Century

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.

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microstructures of an ice core
April 13, 2017

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
December 31, 2016

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
December 31, 2016

Crevices on glacier, Juneau Icefield

Crevices on glacier, Juneau Icefield

Juneau Icefield
August 31, 2016

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.

Ice bergs in the Chukchi Sea, Alaska
July 20, 2013

Sea ice in the Chukchi Sea, Alaska

Sea ice in the Chukchi Sea in 2013.

air bubbles and ice grains in ice
December 31, 2012

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.

July 19, 2012

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 standing in a hole dug in the snow holding a coring tube.
February 29, 2012

Louis Sass with an ice core in a snow pit

Louis Sass with an ice core in a snow pit

Image: Arctic Sea Ice
September 1, 2008

Arctic Sea Ice

Image of sea ice along the Arctic Ocean.

Image: Ice Core

Ice Core

Mikhail Kanevsiy (University of Alaska, Fairbanks) holding a core of ice-rich permafrost from about 2m depth. 

Attribution: Land Resources
Drilling firn cores on the Juneau Icefield, Alaska

Drilling firn cores on the Juneau Icefield, Alaska

Molly Peek and Chris Miele drilling and processing firn cores on the Juneau Icefield, Alaska.