Geologic Map of Alaska

Science Center Objects

In January 2016, the U.S. Geological Survey released the first ever digital geologic map of Alaska. This map reflects more than a century of work and provides a visual context for the abundant mineral and energy resources found throughout the state. The map also is available to use in three different formats: a professional GIS database, a public interactive version via a web browser, and an educational poster that gives a generalized depiction of the geology of Alaska.

The Alaska Geologic Map shows the generalized geology of the state, each color representing a different type or age of rock

The Alaska Geologic Map shows the generalized geology of the state, each color representing a different type or age of rock, from USGS Scientific Investigations Map 3340 - Geologic map of Alaska.(Credit: Frederic Wilson and Keith Labay, USGS. Public domain.)

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Interactive map viewer for the Geologic Map of Alaska (SIM-3340)

This is an interactive version of the Alaska geologic map database which allows a user to view and access many features of the database and map through a standard web browser. In other words, there is no need for or knowledge of specialized GIS software.

Features of the viewer include:

  • Access to both the “generalized” and “detailed” versions of the state geologic map. At startup of the map viewer, the detailed geology is shown by default and also provides access to the full versions of the GIS datasets. The printed version of the state map shows a generalized or simplified version of the geology of Alaska.
  • The table of contents aids in performing various tasks including:
    • switching between the display of generalized and detailed geology
    • showing or hiding the different map layers
    • viewing the map legend
  • Hovering the mouse cursor over the map instantly shows the name of the map unit underneath the cursor.
  • Clicking on the map provides a full description for the specific unit in that location using information from the state map database and also the description from the original source.
  • Additional content will become visible when zooming in.  This includes geologic contacts such as faults or sample locations where a bedrock age determination is available.
  • When zoomed in, clicking on a sample location symbol will provide details about the age determination.
  • A help page can be accessed at any time by clicking the “?” in the upper right corner.

The interactive map viewer is available at:

The Geologic Map of Alaska (SIM-3340)

The geology of Alaska is complex and is made up of rocks and deposits that range from billions of years old to rock and deposits that are forming today.  The rocks of the state were deposited, erupted, intruded, or metamorphosed in geographically separate areas of the Earth and have been assembled in Alaska through the process of plate tectonics.

This digital compilation of Alaskan geology enhances, refines, and integrates all relevant information into one seamless database. The map and associated spatial and attribute data used to create this map have tremendous potential for contributing to solutions of regional environmental and natural-resource problems. The database can be used to produce many different maps for a variety of applications; the state map is just one application of the database.

The last Alaska geologic map was published in 1980. Since that time, new efforts in geologic mapping were carried out across the state during the Alaska Mineral Resource Assessment Program (AMRAP). Additionally, new mapping by the State of Alaska and academics all contributed to the construction of the database from which the map was produced.

Wilson, F.H., Hults, C.P., Mull, C.G, and Karl, S.M, compilers, 2015, Geologic map of Alaska: U.S. Geological Survey Scientific Investigations Map 3340, pamphlet 196 p., 2 sheets, scale 1:1,584,000,

Alaska geology map revealed

(Credit: Frederic Wilson, USGS ASC. Public domain.)

Alaska geology revealed (GIP-168)

The Alaska geologic map database was used to produce this poster, which is a simplified and generalized depiction of the geology of Alaska. It was produced with the non-specialist audience in mind. It is intended to depict the three major rock types, the relative ages of the different units, and aid in the understanding of where potential mineral deposits and energy resources might be found, and ultimately, teach us about the earth history of the state. Rock units are grouped in very broad categories on the basis of age and general rock type. This product is the result of simplifying thousands of individual and very specific rock units into just 39 broad groups. Even with this generalization, the sheer complexity of Alaskan geology remains clear.

Wilson, F.H., and Labay, K.A., 2016, Alaska geology revealed: U.S. Geological Survey General Information Product 168,